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Invention Of Radio

Invention Of Radio

Overview
Within the history of radio
History of radio
The early history of radio is the history of technology that produced radio instruments that use radio waves. Within the timeline of radio, many people contributed theory and inventions in what became radio. Radio development began as "wireless telegraphy"...

, several people were involved in the invention of radio and there were many key inventions in what became the modern systems of wireless
Wireless
Wireless telecommunications is the transfer of information between two or more points that are not physically connected. Distances can be short, such as a few meters for television remote control, or as far as thousands or even millions of kilometers for deep-space radio communications...

. Radio
Radio
Radio is the transmission of signals through free space by modulation of electromagnetic waves with frequencies below those of visible light. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space...

 development began as "wireless telegraphy
Wireless telegraphy
Wireless telegraphy is a historical term used today to apply to early radio telegraph communications techniques and practices, particularly those used during the first three decades of radio before the term radio came into use....

". During the early development of wireless technology, and continuing long after its widespread adoption, disputes persisted as to who could claim credit for the invention of radio. The matter was important for economic, political and nationalistic reasons.

Various scientists proposed that electricity and magnetism
Electromagnetism
Electromagnetism is one of the four fundamental interactions in nature. The other three are the strong interaction, the weak interaction and gravitation...

 were linked.
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Encyclopedia
Within the history of radio
History of radio
The early history of radio is the history of technology that produced radio instruments that use radio waves. Within the timeline of radio, many people contributed theory and inventions in what became radio. Radio development began as "wireless telegraphy"...

, several people were involved in the invention of radio and there were many key inventions in what became the modern systems of wireless
Wireless
Wireless telecommunications is the transfer of information between two or more points that are not physically connected. Distances can be short, such as a few meters for television remote control, or as far as thousands or even millions of kilometers for deep-space radio communications...

. Radio
Radio
Radio is the transmission of signals through free space by modulation of electromagnetic waves with frequencies below those of visible light. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space...

 development began as "wireless telegraphy
Wireless telegraphy
Wireless telegraphy is a historical term used today to apply to early radio telegraph communications techniques and practices, particularly those used during the first three decades of radio before the term radio came into use....

". During the early development of wireless technology, and continuing long after its widespread adoption, disputes persisted as to who could claim credit for the invention of radio. The matter was important for economic, political and nationalistic reasons.

Physics of wireless signalling


Various scientists proposed that electricity and magnetism
Electromagnetism
Electromagnetism is one of the four fundamental interactions in nature. The other three are the strong interaction, the weak interaction and gravitation...

 were linked. In 1802 Gian Domenico Romagnosi
Gian Domenico Romagnosi
Gian Domenico Romagnosi was an Italian philosopher, economist and jurist.-Biography:Gian Domenico Romagnosi was born in Salsomaggiore Terme....

 suggested the relationship between electric current and magnetism but his reports went unnoticed. In 1820 Hans Christian Ørsted
Hans Christian Ørsted
Hans Christian Ørsted was a Danish physicist and chemist who discovered that electric currents create magnetic fields, an important aspect of electromagnetism...

 performed a simple and today widely known experiment on man-made electric current and magnetism. He demonstrated that a wire carrying a current could deflect a magnetized compass
Compass
A compass is a navigational instrument that shows directions in a frame of reference that is stationary relative to the surface of the earth. The frame of reference defines the four cardinal directions – north, south, east, and west. Intermediate directions are also defined...

 needle. Ørsted's work influenced André-Marie Ampère
André-Marie Ampère
André-Marie Ampère was a French physicist and mathematician who is generally regarded as one of the main discoverers of electromagnetism. The SI unit of measurement of electric current, the ampere, is named after him....

 to produce a theory of electromagnetism.

Several different electrical, magnetic or electromagnetic physical phenomena can be used to transmit signals over a distance without intervening wires. The various methods for wireless signal transmissions include:
  • Electrical conduction through the ground, or through water.
  • Magnetic induction
    Electromagnetic induction
    Electromagnetic induction is the production of an electric current across a conductor moving through a magnetic field. It underlies the operation of generators, transformers, induction motors, electric motors, synchronous motors, and solenoids....

  • Capacitive coupling
    Capacitive coupling
    In electronics, capacitive coupling is the transfer of energy within an electrical network by means of the capacitance between circuit nodes. This coupling can have an intentional or accidental effect...

  • Electromagnetic waves
    Electromagnetic radiation
    Electromagnetic radiation is a form of energy that exhibits wave-like behavior as it travels through space...


All these physical phenomena, as well as various other ideas such as conduction through air, were tested for the purpose of communication. Early researchers may not have understood or disclosed which physical effects were responsible for transmitting signals. Early experiments used the existing theories of the movement of charged particles through an electrical conductor. There was no theory of electromagnetic wave propagation to guide experiments before Maxwell's treatise and its verification by Hertz and others.

Capacitive and inductive coupling systems today are used only for short-range special purpose systems. The physical phenomenon used today for long-distance wireless communications involves the use of modulated electromagnetic waves, which is radio.

Radio antennas radiate electromagnetic waves that can reach the receiver
Radio propagation
Radio propagation is the behavior of radio waves when they are transmitted, or propagated from one point on the Earth to another, or into various parts of the atmosphere...

 either by ground wave propagation, by refraction from the ionosphere, known as sky wave propagation, and occasionally by refraction in lower layers of the atmosphere (tropospheric ducting). The ground wave component is the portion of the radiated electromagnetic wave that propagates close to the Earth's surface. It has both direct-wave and ground-reflected components. The direct-wave is limited only by the distance from the transmitter to the horizon plus a distance added by diffraction around the curvature of the earth. The ground-reflected portion of the radiated wave reaches the receiving antenna after being reflected from the Earth's surface. A portion of the ground wave energy radiated by the antenna may also be guided by the Earth's surface as a ground-hugging surface wave
Surface wave
In physics, a surface wave is a mechanical wave that propagates along the interface between differing media, usually two fluids with different densities. A surface wave can also be an electromagnetic wave guided by a refractive index gradient...

.

Any change in the electrical conditions of a circuit, whether internal, such as a change of load, starting and switching operations, short circuits, or external, such as due to lightning, involves a readjustment of the stored electromagnetic and electrostatic energy of the circuit; that is, a so-called transient. Such transient is of the general character of a condenser discharge through an inductive circuit. The phenomenon of the condenser discharge through an inductive circuit therefore is of the greatest importance to the engineer, as the foremost cause of high-voltage and high-frequency troubles in electric circuits.

With the development of radio communication—whether wireless or wired—the condenser discharge through an inductive circuit has assumed a great additional importance since, with the exception of a few of the highest power transoceanic stations, which use power-driven high-frequency alternators, the source of power in the radio communication up to 1922 was the condenser discharge through the inductive circuit, whether as a damped wave or as an undamped wave. In undamped wave radio communication, the condenser discharge circuit is coupled with a source of electric power—a battery—in such a manner, that, without interfering with the character of the oscillation, sufficient energy is fed into the circuit to maintain the oscillation, similarly as in the clock, the pendulum is coupled with a source of mechanical power—weight or spring— so as to maintain its oscillation undamped. The usual method of producing a condenser discharge through an inductive circuit is gradually to charge a condenser from a source of electric power, until the condenser voltage has risen sufficiently high to jump a spark gap (the rotary gap, or quenched gap of the damped wave wireless for instance) and thereby discharge through the inductive circuit.

Theory of electromagnetism





Several scientists speculated that light might be connected with electricity or magnetism. Around 1830 Francesco Zantedeschi
Francesco Zantedeschi
Francesco Zantedeschi was an Italian priest and physicist.-Biography:A native of Dolcè, near Verona, Zantedeschi was for some time professor of physics and philosophy in the Liceo of Venice. Later he accepted the chair of physics in the University of Padua, which he held until 1853 being then...

 suggested a connection between light, electricity, and magnetism. In 1832 Joseph Henry
Joseph Henry
Joseph Henry was an American scientist who served as the first Secretary of the Smithsonian Institution, as well as a founding member of the National Institute for the Promotion of Science, a precursor of the Smithsonian Institution. During his lifetime, he was highly regarded...

 performed experiments detecting electromagnetic effects over a distance of 200 feet (61 m) and postulated the existence of electromagnetic waves.

In 1831, Michael Faraday
Michael Faraday
Michael Faraday, FRS was an English chemist and physicist who contributed to the fields of electromagnetism and electrochemistry....

 began a series of experiments in which he discovered electromagnetic induction
Electromagnetic induction
Electromagnetic induction is the production of an electric current across a conductor moving through a magnetic field. It underlies the operation of generators, transformers, induction motors, electric motors, synchronous motors, and solenoids....

. The relation was mathematically modelled by Faraday's law
Faraday's law of induction
Faraday's law of induction dates from the 1830s, and is a basic law of electromagnetism relating to the operating principles of transformers, inductors, and many types of electrical motors and generators...

, which subsequently became one of the four Maxwell equations
Maxwell's equations
Maxwell's equations are a set of partial differential equations that, together with the Lorentz force law, form the foundation of classical electrodynamics, classical optics, and electric circuits. These fields in turn underlie modern electrical and communications technologies.Maxwell's equations...

. Faraday proposed that electromagnetic forces extended into the empty space around the conductor, but did not complete his work involving that proposal. In 1846 Michael Faraday speculated that light was a wave disturbance in a force field".

Between 1861 and 1865, based on the earlier experimental work of Faraday and other scientists, James Clerk Maxwell
James Clerk Maxwell
James Clerk Maxwell of Glenlair was a Scottish physicist and mathematician. His most prominent achievement was formulating classical electromagnetic theory. This united all previously unrelated observations, experiments and equations of electricity, magnetism and optics into a consistent theory...

 developed his theory of electromagnetism, which predicted the existence of electromagnetic waves. In 1873 Maxwell described the theoretical basis of the propagation of electromagnetic waves in his paper to the Royal Society
Royal Society
The Royal Society of London for Improving Natural Knowledge, known simply as the Royal Society, is a learned society for science, and is possibly the oldest such society in existence. Founded in November 1660, it was granted a Royal Charter by King Charles II as the "Royal Society of London"...

, "A Dynamical Theory of the Electromagnetic Field
A Dynamical Theory of the Electromagnetic Field
"A Dynamical Theory of the Electromagnetic Field" is the third of James Clerk Maxwell's papers regarding electromagnetism, published in 1865. It is the paper in which the original set of four Maxwell's equations first appeared...

."

Based on the experimental work of Faraday and other physicists, James Clerk Maxwell
James Clerk Maxwell
James Clerk Maxwell of Glenlair was a Scottish physicist and mathematician. His most prominent achievement was formulating classical electromagnetic theory. This united all previously unrelated observations, experiments and equations of electricity, magnetism and optics into a consistent theory...

 in 1864 developed the theory of electromagnetism
Electromagnetism
Electromagnetism is one of the four fundamental interactions in nature. The other three are the strong interaction, the weak interaction and gravitation...

 that predicted the existence of electromagnetic waves, which include radio waves. This theory united all previously unrelated observations, experiments and equations of electricity, magnetism, and optics into a consistent theory. His set of equations—Maxwell's equations
Maxwell's equations
Maxwell's equations are a set of partial differential equations that, together with the Lorentz force law, form the foundation of classical electrodynamics, classical optics, and electric circuits. These fields in turn underlie modern electrical and communications technologies.Maxwell's equations...

—demonstrated that electricity, magnetism, and light are all manifestations of the same phenomenon, the electromagnetic field
Electromagnetic field
An electromagnetic field is a physical field produced by moving electrically charged objects. It affects the behavior of charged objects in the vicinity of the field. The electromagnetic field extends indefinitely throughout space and describes the electromagnetic interaction...

. Subsequently, all other classic laws or equations of these disciplines were special cases of Maxwell's equations. Maxwell's work in electromagnetism has been called the "second great unification in physics".

Although Maxwell did not transmit or receive radio waves his equations still remain the basis of all radio design. Berend Wilhelm Feddersen
Berend Wilhelm Feddersen
Berend Wilhelm Feddersen was a German physicist.-Biography:Feddersen lived from 1858 as a private scholar in Leipzig. In 1859 he succeeded in experiments with the Leyden jar to prove that every single electric spark discharge composed of oscillations...

 (German physicist) in 1859, as a private scholar in Leipzig
Leipzig
Leipzig Leipzig has always been a trade city, situated during the time of the Holy Roman Empire at the intersection of the Via Regia and Via Imperii, two important trade routes. At one time, Leipzig was one of the major European centres of learning and culture in fields such as music and publishing...

, succeeded in experiments with the Leyden jar to prove that electric spark
Electric spark
An electric spark is a type of electrostatic discharge that occurs when an electric field creates an ionized electrically conductive channel in air producing a brief emission of light and sound. A spark is formed when the electric field strength exceeds the dielectric field strength of air...

s were composed of discharge (damped) oscillations. He realized that they arise from a coil, capacitor and resistor existing electrical circuit oscillations.

Formative "wireless" methods


In April 1872 William Henry Ward
William Henry Ward
William Henry Ward on 30 April 1872 was granted a USA patent for "Improvement for collecting electricity for telegraphing" . He theorized that an "electrical layer in the atmosphere" could carry signals like a telegraph wire, and thus is sometimes listed among supposed inventors of radio.-External...

 received for radio development. However, this patent did not refer to any known scientific theory of electromagnetism and could never have received and transmitted radio waves.

A few months after Ward received his patent, Mahlon Loomis
Mahlon Loomis
Mahlon Loomis was an early wireless telegraph experimenter.-Early history:...

 of West Virginia
West Virginia
West Virginia is a state in the Appalachian and Southeastern regions of the United States, bordered by Virginia to the southeast, Kentucky to the southwest, Ohio to the northwest, Pennsylvania to the northeast and Maryland to the east...

 received for a "wireless telegraph" in July 1872. This claimed to utilize atmospheric electricity
Atmospheric electricity
Atmospheric electricity is the regular diurnal variations of the Earth's atmospheric electromagnetic network . The Earth's surface, the ionosphere, and the atmosphere is known as the global atmospheric electrical circuit...

 to eliminate the overhead wire used by the existing telegraph systems. It did not contain diagrams or specific methods and it did not refer to or incorporate any known scientific theory. It is substantially similar to William Henry Ward
William Henry Ward
William Henry Ward on 30 April 1872 was granted a USA patent for "Improvement for collecting electricity for telegraphing" . He theorized that an "electrical layer in the atmosphere" could carry signals like a telegraph wire, and thus is sometimes listed among supposed inventors of radio.-External...

's patent and could not have transmitted and received radio waves.

Towards the end of 1875, while experimenting with the telegraph, Thomas Edison
Thomas Edison
Thomas Alva Edison was an American inventor and businessman. He developed many devices that greatly influenced life around the world, including the phonograph, the motion picture camera, and a long-lasting, practical electric light bulb. In addition, he created the world’s first industrial...

 noted a phenomenon that he termed "etheric force
Etheric force
Etheric force, a term coined by Thomas Edison to describe a phenomenon that was later to be understood as high frequency electromagnetic waves, effectively, radio...

", announcing it to the press on November 28. He abandoned this research when Elihu Thomson
Elihu Thomson
Elihu Thomson was an American engineer and inventor who was instrumental in the founding of major electrical companies in the United States, the United Kingdom and France.-Early life:...

, among others, ridiculed the idea. The idea was not based on the electromagnetic waves described by Maxwell. In 1885, Edison took out on a system of electrical wireless communication between ships (which later he sold to the Marconi Company
Marconi Company
The Marconi Company Ltd. was founded by Guglielmo Marconi in 1897 as The Wireless Telegraph & Signal Company...

). The patent, however, was based on the mutual-inductively coupled or magnetically coupled communication.

Claims have been made that Murray, Kentucky
Murray, Kentucky
Murray is a city in Calloway County, Kentucky, United States. The population was 17,741 at the 2010 census and has a micropolitan area population of 37,191. It is the 22nd largest city in Kentucky...

 farmer Nathan Stubblefield
Nathan Stubblefield
Nathan B. Stubblefield was an American inventor and Kentucky melon farmer. It has been claimed that Stubblefield invented the radio before either Nikola Tesla or Guglielmo Marconi, but his devices seem to have worked by audio frequency induction or, later, audio frequency earth conduction rather...

 developed radio between 1885 and 1892, before either Tesla or Marconi, but his devices seemed to have worked by induction
Electromagnetic induction
Electromagnetic induction is the production of an electric current across a conductor moving through a magnetic field. It underlies the operation of generators, transformers, induction motors, electric motors, synchronous motors, and solenoids....

 transmission rather than radio transmission
Radio propagation
Radio propagation is the behavior of radio waves when they are transmitted, or propagated from one point on the Earth to another, or into various parts of the atmosphere...

.

In 1878, David E. Hughes
David E. Hughes
David Edward Hughes , was a British scientist and musician. Hughes was co-inventor of the microphone, a harpist and a professor of music.-Biography:...

 noticed that sparks could be heard in a telephone receiver when experimenting with his carbon microphone. He developed this carbon-based detector further and eventually could detect signals over a few hundred yards. He demonstrated his discovery to the Royal Society in 1880, but was told it was merely induction
Electromagnetic induction
Electromagnetic induction is the production of an electric current across a conductor moving through a magnetic field. It underlies the operation of generators, transformers, induction motors, electric motors, synchronous motors, and solenoids....

, and therefore abandoned further research, although there have been later claims that he did, in fact, transmit and receive electromagnetic waves. While Professor Hughes was continuing his investigations in this direction, Hertz's papers were published, and then he thought it too late to bring forward these earlier experiments.

Early radio development




The key invention for the beginning of "wireless transmission of data using the entire frequency spectrum", known as the spark-gap transmitter
Spark-gap transmitter
A spark-gap transmitter is a device for generating radio frequency electromagnetic waves using a spark gap.These devices served as the transmitters for most wireless telegraphy systems for the first three decades of radio and the first demonstrations of practical radio were carried out using them...

, has been attributed to various men. Marconi equipped ships with lifesaving wireless communications and established the first transatlantic radio service. Tesla developed means to reliably produce radio frequency electrical currents, publicly demonstrated the principles of radio, and transmitted long distance signals.

In the late 19th century it was clear to various scientists and experimenters that wireless communication was possible. Various theoretical and experimental innovations led to the development of radio and the communication system we know today. Some early work was done by local effects
Near and far field
The near field and far field and the transition zone are regions of the electromagnetic radiation field that emanates from a transmitting antenna, or as a result of radiation scattering off an object...

 and experiment
Experiment
An experiment is a methodical procedure carried out with the goal of verifying, falsifying, or establishing the validity of a hypothesis. Experiments vary greatly in their goal and scale, but always rely on repeatable procedure and logical analysis of the results...

s of electromagnetic induction
Electromagnetic induction
Electromagnetic induction is the production of an electric current across a conductor moving through a magnetic field. It underlies the operation of generators, transformers, induction motors, electric motors, synchronous motors, and solenoids....

. Many understood that there was nothing similar to the "ethereal
Aether (classical element)
According to ancient and medieval science aether , also spelled æther or ether, is the material that fills the region of the universe above the terrestrial sphere.-Mythological origins:...

 telegraphy"
and telegraphy by induction
Radio-frequency induction
Radio-frequency induction or RF induction is the use of a radio frequency magnetic field to transfer energy by means of electromagnetic induction in the near field...

, the phenomena being wholly distinct. Wireless telegraphy was beginning to take hold and the practice of transmitting messages without wires was being developed. Many people worked on developing the devices and improvements.

Early radio's origin and development of old, or damped wave-coherer, methods began with Joseph Henry. He was the first (1838–42) to produce high frequency electrical oscillations, and to point out and experimentally demonstrate that the discharge of a condenser is under certain conditions oscillatory, or, as he puts it, consists "of a principal discharge in one direction and then several reflex actions backward and forward, each more feeble than the preceding until equilibrium is attained". This view was also later adopted by Helmholz, but the mathematical demonstration of this fact was first given by Lord Kelvin in his paper on "Transient Electric Currents".

In 1870 the German physicist Wilhelm von Bezold
Wilhelm von Bezold
Johann Friedrich Wilhelm von Bezold was a German physicist and meteorologist born in Munich, Kingdom of Bavaria....

 discovered and experimentally demonstrated the fact that the advancing and reflected oscillations produced in conductors by a condenser discharge gave rise to interference phenomena. Professors Elihu Thomson
Elihu Thomson
Elihu Thomson was an American engineer and inventor who was instrumental in the founding of major electrical companies in the United States, the United Kingdom and France.-Early life:...

 and E. J. Houston in 1876 made a number of experiments and observations on high frequency oscillatory discharges. In 1883 G. F. Fitzgerald suggested at a British Association meeting that electromagnetic waves could be generated by the discharge of a condenser, but the suggestion was not followed up, possibly because no means was known for detecting the waves.

Hertz discovered a method of detecting such waves by means of a minute spark-gap and, before March 30, 1888, had concluded his remarkable series of researches in which for the first time electromagnetic waves were actually produced by a spark-gap and radiating conductor and received and detected at a distance by a tuned receiving circuit. Hertz changed the frequency of his radiated waves by altering the inductance or capacity of his radiating conductor or antenna, and reflected and focused the electromagnetic waves, thus demonstrating the correctness of Maxwell's electromagnetic theory of light. After Hertz, Sir William Crookes
William Crookes
Sir William Crookes, OM, FRS was a British chemist and physicist who attended the Royal College of Chemistry, London, and worked on spectroscopy...

 discussed the matter of wireless in some detail. Professor Amos Emerson Dolbear
Amos Dolbear
Amos Emerson Dolbear was an American physicist and inventor. His patents interfered with Guglielmo Marconi's planned activities in the U.S. Dolbear researched electrical spark conversion into sound waves and electrical impulses. He was a professor at University of Kentucky in Lexington from 1868...

 also suggested the same thing.

Hertz


Between 1886 and 1888, Heinrich Rudolf Hertz
Heinrich Rudolf Hertz
Heinrich Rudolf Hertz was a German physicist who clarified and expanded the electromagnetic theory of light that had been put forth by Maxwell...

 studied Maxwell's theory and validated it through experiment. Concerning wireless telegraphy, he demonstrated the transmission and reception of the electromagnetic waves predicted by Maxwell and intentionally transmitted and received radio. Hertz changed the frequency of his radiated waves by altering the inductance or capacity of his radiating conductor or antenna, and reflected and focused the electromagnetic waves, thus demonstrating the correctness of Maxwell's electromagnetic theory of light. Famously, he saw no practical use for his discovery.

In his UHF
Ultra high frequency
Ultra-High Frequency designates the ITU Radio frequency range of electromagnetic waves between 300 MHz and 3 GHz , also known as the decimetre band or decimetre wave as the wavelengths range from one to ten decimetres...

 experiments, he transmitted and received radio waves over short distances and showed that the properties of radio waves were consistent with Maxwell’s electromagnetic theory. He demonstrated that radio radiation (now called electromagnetic radiation) had all the properties of waves, and discovered that the electromagnetic equations could be reformulated into a partial differential equation
Partial differential equation
In mathematics, partial differential equations are a type of differential equation, i.e., a relation involving an unknown function of several independent variables and their partial derivatives with respect to those variables...

 called the wave equation
Wave equation
The wave equation is an important second-order linear partial differential equation for the description of waves – as they occur in physics – such as sound waves, light waves and water waves. It arises in fields like acoustics, electromagnetics, and fluid dynamics...

.





Hertz’s setup for a source and detector of radio waves (then called Hertzian waves in his honor) was the first intentional and unequivocal transmission and reception of radio waves
Radio waves
Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. Radio waves have frequencies from 300 GHz to as low as 3 kHz, and corresponding wavelengths from 1 millimeter to 100 kilometers. Like all other electromagnetic waves,...

 through free space. The first of the papers published ("On Very Rapid Electric Oscillations") gives, generally in the actual order of time, the course of the investigation as far as it was carried out up to the end of the year 1886 and the beginning of 1887.

Hertz, though, did not devise a system for actual general use nor describe the application of the technology and seemed uninterested in the practical importance of his experiments. Asked about the ramifications of his discoveries, Hertz replied, "Nothing, I guess." Hertz also stated, "I do not think that the wireless waves I have discovered will have any practical application." Hertz died in 1894, and the art of radio was left to others to implement into a practical form.

Branly


In 1890, Édouard Branly
Edouard Branly
Édouard Eugène Désiré Branly was a French inventor, physicist and professor at the Institut Catholique de Paris. He is primarily known for his early involvement in wireless telegraphy and his invention of the Branly coherer around 1890.-Biography:The coherer was the first widely used detector for...

 demonstrated what he later called the "radio-conductor," which Lodge in 1893 named the coherer
Coherer
The coherer was a primitive form of radio signal detector used in the first radio receivers during the wireless telegraphy era at the beginning of the twentieth century. Invented around 1890 by French scientist Édouard Branly, it consisted of a tube or capsule containing two electrodes spaced a...

, the first sensitive device for detecting radio waves. Shortly after the experiments of Hertz, Dr. Branly discovered that loose metal filings, which in a normal state have a high electrical resistance, lose this resistance in the presence of electric oscillations and become practically conductors of electricity. This Branly showed by placing metal filings in a glass box or tube, and making them part of an ordinary electric circuit. According to the common explanation, when electric waves are set up in the neighborhood of this circuit, electromotive forces are generated in it which appear to bring the filings more closely together, that is, to cohere, and thus their electrical resistance decreases, from which cause this piece of apparatus was termed by Sir Oliver Lodge a coherer. Hence the receiving instrument, which may be a telegraph relay, that normally would not indicate any sign of current from the small battery, can be operated when electric oscillations are set up. Prof. Branly further found that when the filings had once cohered they retained their low resistance until shaken apart, for instance, by tapping on the tube. The coherer, however, was not sensitive enough to be used reliably as radio developed.

Tesla


In 1891 Nikola Tesla
Nikola Tesla
Nikola Tesla was a Serbian-American inventor, mechanical engineer, and electrical engineer...

 began his research into radio. Around July 1891 he developed various alternator apparatus
Alternator
An alternator is an electromechanical device that converts mechanical energy to electrical energy in the form of alternating current.Most alternators use a rotating magnetic field but linear alternators are occasionally used...

 that produced 15,000 cycles per second
Very low frequency
225px|thumb|right|A VLF receiving antenna at [[Palmer Station]], Antarctica, operated by Stanford UniversityVery low frequency or VLF refers to radio frequencies in the range of 3 kHz to 30 kHz. Since there is not much bandwidth in this band of the radio spectrum, only the very simplest signals...

. In 1892 he delivered a lecture called "Experiments with Alternate Currents of High Potential and High Frequency" before the Institution of Electrical Engineers
Institution of Electrical Engineers
The Institution of Electrical Engineers was a British professional organisation of electronics, electrical, manufacturing, and Information Technology professionals, especially electrical engineers. The I.E.E...

 of London, in which he suggested that messages could be transmitted without wires. He repeated this presentation at the Royal Institution
Royal Institution
The Royal Institution of Great Britain is an organization devoted to scientific education and research, based in London.-Overview:...

 and at the Société Française de Physique in Paris. Tesla realized he gained, by the use of very high frequencies, many advantages in his experiments, such as the possibilities of working with one lead and of doing away with the leading-in wire. In transmitting impulses through conductors, he dealt with high pressure and high flow, in the ordinary interpretation of these terms. Towards the end of the lecture, he proposed that sending over the wire current vibrations of very high frequencies at enormous distance without affecting greatly the character of the vibrations and that telephony could be rendered practicable across the Atlantic. He also proposed transmission through the Earth. Tesla captured the attention of the whole scientific world by his fascinating experiments on high frequency electric currents. He stimulated the scientific imagination of others as well as displayed his own, and created a widespread interest in his brilliant demonstrations. Accordingly there are seven elements in the complete oscillation-producing appliance, which are as follows:
  • The induction coil transformer or source of electromotive force
    Electromotive force
    In physics, electromotive force, emf , or electromotance refers to voltage generated by a battery or by the magnetic force according to Faraday's Law, which states that a time varying magnetic field will induce an electric current.It is important to note that the electromotive "force" is not a...

    .
  • The condenser
    Capacitor
    A capacitor is a passive two-terminal electrical component used to store energy in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors separated by a dielectric ; for example, one common construction consists of metal foils separated...

    .
  • The discharger
    Discharger
    A discharger in electronics is a device or circuit that releases stored energy or electric charge from a battery, capacitor or other source.Discharger types include:* metal probe with insulated handle & ground wire, and sometimes resistor...

     or spark ball
    Spark gap
    A spark gap consists of an arrangement of two conducting electrodes separated by a gap usually filled with a gas such as air, designed to allow an electric spark to pass between the conductors. When the voltage difference between the conductors exceeds the gap's breakdown voltage, a spark forms,...

    s.
  • The arc quenching inductances.
  • The oscillation transformer.
  • The adjustable inductance for varying the period.
  • The controller or key
    Telegraph key
    Telegraph key is a general term for any switching device used primarily to send Morse code. Similar keys are used for all forms of manual telegraphy, such as in electrical telegraph and radio telegraphy.- Types of keys :...

     in the primary circuit of the coil or transformer.

These several elements have each to be considered separately with reference to their best practical forms for various purposes. When the key is closed, and the apparatus in operation, there are trains of intermittent electrical oscillations set up in the circuit, and if the terminals of the secondary circuit of the oscillation transformer are near together, there is high potential high frequency oscillatory sparks passing between them. The above-described apparatus in a typical form is generally called a Tesla apparatus for the production of high frequency electric currents.


"On Light and Other High Frequency Phenomena"


In 1893, at St. Louis, Missouri
St. Louis, Missouri
St. Louis is an independent city on the eastern border of Missouri, United States. With a population of 319,294, it was the 58th-largest U.S. city at the 2010 U.S. Census. The Greater St...

, Tesla gave a public demonstration, "On Light and Other High Frequency Phenomena", of wireless communication. Addressing the Franklin Institute
Franklin Institute
The Franklin Institute is a museum in Philadelphia, Pennsylvania, and one of the oldest centers of science education and development in the United States, dating to 1824. The Institute also houses the Benjamin Franklin National Memorial.-History:On February 5, 1824, Samuel Vaughn Merrick and...

in Philadelphia, he described in detail the principles of early radio communication. The lecture apparatus that Tesla used contained all the elements that were incorporated into radio systems before the development of the "oscillation valve", the early vacuum tube
Vacuum tube
In electronics, a vacuum tube, electron tube , or thermionic valve , reduced to simply "tube" or "valve" in everyday parlance, is a device that relies on the flow of electric current through a vacuum...

. The lecture delivered before the Franklin Institute, at Philadelphia, occurred on February 24, 1893. The variety of Tesla's radio frequency systems were again demonstrated during when he presented to meetings of the National Electric Light Association
National Electric Light Association
The National Electric Light Association was a national United States trade association including the operators of central power generation stations and interested individuals. Founded in 1885 by G. S. Bowen Terry and Charles A. Brown, it represented the interests of various private companies...

, at St. Louis, on March I, 1893. Afterward, the principle of radio communication (sending signals through space to receivers) was publicized widely from Tesla's experiments and demonstrations. On August 25, 1893, Tesla delivered the lecture "Mechanical and Electrical Oscillators", before the International Electrical Congress, in the hall adjoining the Agricultural Building, at the World's Fair, Chicago
World's Columbian Exposition
The World's Columbian Exposition was a World's Fair held in Chicago in 1893 to celebrate the 400th anniversary of Christopher Columbus's arrival in the New World in 1492. Chicago bested New York City; Washington, D.C.; and St...

.

The high-frequency phenomena which Tesla first developed and displayed had scientific rather than practical interest; but Tesla called attention to the fact that by taking the Tesla oscillator, grounding one side of it and connecting the other to an insulated body of large surface, it should be possible to transmit electric oscillations to a great distance, and to communicate intelligence in this way to other oscillators in sympathetic resonance therewith. This was going far toward the invention of radio-telegraphy as known in the early 20th century, as stated by the Electrical World in 1917.

Transmission and radiation of radio frequency energy was a feature exhibited in the experiments by Tesla which he proposed might be used for the telecommunication
Telecommunication
Telecommunication is the transmission of information over significant distances to communicate. In earlier times, telecommunications involved the use of visual signals, such as beacons, smoke signals, semaphore telegraphs, signal flags, and optical heliographs, or audio messages via coded...

 of information
Information
Information in its most restricted technical sense is a message or collection of messages that consists of an ordered sequence of symbols, or it is the meaning that can be interpreted from such a message or collection of messages. Information can be recorded or transmitted. It can be recorded as...

. The Tesla method
Wireless energy transfer
Wireless energy transfer or wireless power is the transmission of electrical energy from a power source to an electrical load without artificial interconnecting conductors. Wireless transmission is useful in cases where interconnecting wires are inconvenient, hazardous, or impossible...

 was mentioned in New York in 1897. In Buffalo, New York, he referred to devised means for transmission of electromotive force
Electromotive force
In physics, electromotive force, emf , or electromotance refers to voltage generated by a battery or by the magnetic force according to Faraday's Law, which states that a time varying magnetic field will induce an electric current.It is important to note that the electromotive "force" is not a...

s, much higher than practical with ordinary apparatus, and the transmission of power from station to station without the employment of any connecting wire. Tesla later, on April 6, 1897, explained his methods of the transformation of electrical energy by oscillatory condenser discharges in his lecture "The stream of Lenard and Roentgen and novel apparatus for their production". He demonstrated his subject by a fine array of improved apparatus, in which a few feet of wire were made as efficient as miles under old systems.


In 1894, T. C. Martin
Thomas Commerford Martin
Thomas Commerford Martin was an American electrical engineer and editor, born in London, England. His father worked with Lord Kelvin and other pioneers of submarine telegraph cables, and Martin spent much time on the cable-laying ship SS Great Eastern. Educated as a theological student, Martin...

 published "The Inventions, Researches and Writings of Nikola Tesla", detailing the work of Tesla in the previous years. Various scientists, inventors, and experimenters began to investigate wireless methods. Telsa's work contained coupled oscillation circuits having capacity and inductance in series. In 1897, Tesla applied for two key United States radio patents, , first radio system patent, and (later subdivided into) , for protection of his interests of the radio arts. Tesla also developed sensitive electromagnetic receivers, that were unlike the less responsive coherers later used by other early experimenters.

Shortly thereafter, he began to develop wireless remote control
Remote control
A remote control is a component of an electronics device, most commonly a television set, used for operating the television device wirelessly from a short line-of-sight distance.The remote control is usually contracted to remote...

 devices. In 1898, he demonstrated a radio controlled boat in Madison Square Garden
Madison Square Garden (1890)
Madison Square Garden was an indoor arena in New York City, the second by that name, and the second to be located at 26th Street and Madison Avenue in Manhattan...

 that allowed secure communication
Secure communication
When two entities are communicating and do not want a third party to listen in, they need to communicate in a way not susceptible to eavesdropping or interception. This is known as communicating in a secure manner or secure communication...

 between transmitter and receiver. Between 1895 and 1897, Tesla received wireless signals transmitted via short distances in his lectures. Between 1897 and the first decade of the 1900s, he transmitted over medium ranges. Tesla had predicted that not only would intelligible signals be transmitted over long distances without wires, but electric power as well. He later published articles, such as
"The True Wireless", and "The Transmission of Electric Energy Without Wires", concerning the World Wireless System research.

de Moura


Roberto Landell de Moura, a Brazilian priest and scientist, went to Rome in 1878 and studied at the South American College
South American College in Rome
The South American College in Rome is one of the Roman Colleges of the Roman Catholic Church, for students from Central and South America.-History:...

 and Pontifical Gregorian University
Pontifical Gregorian University
The Pontifical Gregorian University is a pontifical university located in Rome, Italy.Heir of the Roman College founded by Saint Ignatius of Loyola over 460 years ago, the Gregorian University was the first university founded by the Jesuits...

, where he studied physics and chemistry. He completed his clerical training in Rome, graduating in theology and was ordained priest in 1886. In Rome, he started studying physics and electricity. When he returned to Brazil, he conducted experiments in wireless in Campinas
Campinas
Campinas is a city and municipality located in the coastal interior of the state of São Paulo, Brazil. is the administrative center of the meso-region of the same name, with 3,783,597 inhabitants as of the 2010 Census, consisting of 49 cities....

 and São Paulo
São Paulo
São Paulo is the largest city in Brazil, the largest city in the southern hemisphere and South America, and the world's seventh largest city by population. The metropolis is anchor to the São Paulo metropolitan area, ranked as the second-most populous metropolitan area in the Americas and among...

 (1892–1893). The experiments of de Moura were performed in the presence of the English Vice Consul S. Paul, Percy Parmenter, Charles Lupton
Charles Lupton
Captain Charles Roger Lupton was a World War I flying ace credited with five aerial victories.-References:...

, and other persons of high social position. Upon observing the experiments, Rodriguez Botet, giving news of the trials, said he was not far from the moment of the consecration of Landell as an author of radio discoveries. The wireless telephony is reputed the most important discoveries of Landell. De Moura did later pursue and receive several patents on wireless technology. He would later obtain for a wireless telephone.

Lodge


One of the first investigators to notice and measure stationary waves on wires produced by direct coupling
Direct coupling
In electronics, direct coupling is a way of interconnecting two circuits such that, in addition to transferring the AC signal , the first stage also provides DC bias to the next...

 (resonance
Resonance
In physics, resonance is the tendency of a system to oscillate at a greater amplitude at some frequencies than at others. These are known as the system's resonant frequencies...

) with the coatings of a Leyden jar was Sir Oliver Lodge, entitled "Experiments On The Discharge Of Leyden Jars" (1891). On June, 1, 1894, Oliver Lodge at the Royal Institution lectures, delivered "The Work of Hertz and Some of His Successors". Two years after Tesla's high potential and high frequency lecture and five years after Hertz's signals, Lodge performed transmission on August 14, 1894. This was a year before Marconi's initial experiments. Lodge did this at a meeting of the British Association for the Advancement of Science
British Association for the Advancement of Science
frame|right|"The BA" logoThe British Association for the Advancement of Science or the British Science Association, formerly known as the BA, is a learned society with the object of promoting science, directing general attention to scientific matters, and facilitating interaction between...

 at Oxford University. Also in 1894, Lodge would state that Alexander Muirhead
Alexander Muirhead
Alexander Muirhead, FRS, born in East Saltoun, East Lothian, Scotland was an electrical engineer specialising in wireless telegraphy.-Biography:...

 clearly foresaw the telegraphic importance of the transmission of transverse Hertzian waves. A convenient method of establishing stationary electric waves on wires is one which generally attribute to Ernst Lecher
Ernst Lecher
Ernst Lecher was an Austrian physicist who, from 1909, was head of the First Institute of Physics in Vienna. He is remembered for developing an apparatus— "Lecher lines"—to measure the wavelength and frequency of electromagnetic waves...

, and call the Lecher arrangement
Lecher lines
In electronics, a Lecher line or Lecher wires is a pair of parallel wires or rods that were used to measure the wavelength of radio waves, mainly at UHF and microwave frequencies. They form a short length of balanced transmission line. When attached to a source of radio frequency power such as a...

. As a matter of fact, it originated with Lodge and Hertz, whilst Edouard Sarasin and Lucien de la Rive gave it an improved form.

On that day in August 1894, Lodge demonstrated the reception of Morse code
Morse code
Morse code is a method of transmitting textual information as a series of on-off tones, lights, or clicks that can be directly understood by a skilled listener or observer without special equipment...

 signalling via radio waves using a "coherer
Coherer
The coherer was a primitive form of radio signal detector used in the first radio receivers during the wireless telegraphy era at the beginning of the twentieth century. Invented around 1890 by French scientist Édouard Branly, it consisted of a tube or capsule containing two electrodes spaced a...

". He later improved Branly's coherer by adding a "trembler" which dislodged clumped filings, thus restoring the device's sensitivity. In August 1898 he got , "Electric Telegraphy", that made wireless signals using Ruhmkorff coils or Tesla coil
Tesla coil
A Tesla coil is a type of resonant transformer circuit invented by Nikola Tesla around 1891. It is used to produce high voltage, low current, high frequency alternating current electricity. Tesla coils produce higher current than the other source of high voltage discharges, electrostatic machines...

s for the transmitter and a Branly coherer for the detector. This patent was utilizing the concept of "syntonic" tuning. In 1912 Lodge sold the patent to Marconi.
Lodge 1894 lecture

Lodge's June 1, 1894 lecture before the Royal Institution. described among other things the following:
  1. Filings coherer
  2. Vacuum coherer
  3. Automatic coherer tapper
  4. Metallic focusing wave reflector
  5. Grounded conductor
  6. Coupled system
  7. Method of detection

In this lecture, Lodge stated that in his estimate the apparatus used would respond to signals at a distance of 0.5 mile (0.80467 km).

In 1894 Lodge showed that the Branly coherer could be employed to transmit telegraphic signals, and in order that the filings should not remain "cohered" after the cessation of the electric oscillations, he devised an electro-mechanical "tapper" on the principle of the ordinary "buzzer," or electric door-bell, the hammer of which was caused to tap the glass tube as long as the electric oscillations continued. The filings thus virtually take the place of a key in the ordinary telegraph circuit. In the normal state the key is open; in the presence of electrical oscillations the key is closed. Thus, by opening and closing the key for a longer or shorter period, signals corresponding to dots and dashes may be produced. In other words, by setting up electric oscillations for periods of time corresponding to dots and dashes, messages may be transmitted from the sending station, and if, at the receiving station, a recording instrument (controlled by the coherer), such as the ordinary Morse register, be provided, a record of the message in dots and dashes may be obtained. Dr. Lodge in fact used a tapper operated continuously by clockwork.

In 1894, with the help of the Branly filings tube, Lodge gave a couple of demonstrations, one in June at the Royal Institution
Royal Institution
The Royal Institution of Great Britain is an organization devoted to scientific education and research, based in London.-Overview:...

 at Oxford and one in August at Oxford, to the British Association, using Hertz oscillators for transmitting signals, using a Morse key in connection with the sending coil, and a Thomson marine galvanometer for receiving them—sending the signals from one room to another through walls, and so on. Lodge sent them also across the quadrangle
Quadrangle (architecture)
In architecture, a quadrangle is a space or courtyard, usually rectangular in plan, the sides of which are entirely or mainly occupied by parts of a large building. The word is probably most closely associated with college or university campus architecture, but quadrangles may be found in other...

 of Liverpool College, but he applied very small power and did not try for big distances. At that time Dr. Alexander Muirhead
Alexander Muirhead
Alexander Muirhead, FRS, born in East Saltoun, East Lothian, Scotland was an electrical engineer specialising in wireless telegraphy.-Biography:...

 was struck with its applicability to practical telegraphy, and when in 1896 Sir William Preece told the British Association meeting (as it happened in his laboratory) at Liverpool that an Italian gentleman (at that time unknown)
Guglielmo Marconi
Guglielmo Marconi was an Italian inventor, known as the father of long distance radio transmission and for his development of Marconi's law and a radio telegraph system. Marconi is often credited as the inventor of radio, and indeed he shared the 1909 Nobel Prize in Physics with Karl Ferdinand...

 was interesting the Post Office in a secret box, Lodge knew practically what the box must contain, and immediately afterwards (the same day) he showed to a few friends a Morse tape instrument, very roughly working on that plan. Mr. Marconi and Sir William Preece together interested the whole world in the subject; great power was applied to the sender, and the matter became of financial importance. However, the American Patent Office gave Lodge a telegraphic patent based on his work, as published in 1894, after proof that this book had reached America in or before 1895.

Bose


In November 1894, the Indian physicist, Jagadish Chandra Bose, demonstrated publicly the use of radio waves in Calcutta
Kolkata
Kolkata , formerly known as Calcutta, is the capital of the Indian state of West Bengal. Located on the east bank of the Hooghly River, it was the commercial capital of East India...

, but he was not interested in patenting his work. Bose ignited gunpowder and rang a bell at a distance using electromagnetic waves, proving that communication signals can be sent without using wires. He sent and received radio waves over distance but did not commercially exploit this achievement.

The 1895 public demonstration by Bose in Calcutta was before Marconi's wireless signalling experiment on Salisbury Plain
Salisbury Plain
Salisbury Plain is a chalk plateau in central southern England covering . It is part of the Southern England Chalk Formation and largely lies within the county of Wiltshire, with a little in Hampshire. The plain is famous for its rich archaeology, including Stonehenge, one of England's best known...

 in England in May 1897. Bose demonstrated the ability of the electric rays to travel from the lecture room, and through an intervening room and passage, to a third room 75 feet (22.9 m) distant from the radiator, thus passing through three solid walls on the way, as well as the body of the chairman (who happened to be the Lieutenant-Governor). The receiver at this distance still had energy enough to make a contact which set a bell ringing, discharged a pistol, and exploded a miniature mine. To get this result from his small radiator, Bose set up an apparatus which curiously anticipated the lofty 'antennae' of modern wireless telegraphy— a circular metal plate at the top of a pole, 20 feet (6.1 m) high, being put in connection with the radiator and a similar one with the receiving apparatus.

The form of 'Coherer' devised by Professor Bose, and described by him at the end of his paper 'On a new Electro Polariscope' allowed for the sensibility and range to appear to leave little to be desired at the time. In 1896, the Daily Chronicle
Daily Chronicle
The Daily Chronicle was a British newspaper that was published from 1872 to 1930 when it merged with the Daily News to become the News Chronicle.-History:...

 of England reported on his UHF experiments: "The inventor (J.C. Bose) has transmitted signals to a distance of nearly a mile and herein lies the first and obvious and exceedingly valuable application of this new theoretical marvel."

After Bose's Friday Evening Discourses at the Royal Institution
Royal Institution
The Royal Institution of Great Britain is an organization devoted to scientific education and research, based in London.-Overview:...

, The Electric Engineer expressed 'surprise that no secret was at any time made as to its construction, so that it has been open to all the world to adopt it for practical and possibly money-making purposes.'
Bose was sometimes, and not unnaturally, criticised as unpractical for making no profit from his inventions.

In 1899, Bose announced the development of an "iron-mercury-iron coherer
Coherer
The coherer was a primitive form of radio signal detector used in the first radio receivers during the wireless telegraphy era at the beginning of the twentieth century. Invented around 1890 by French scientist Édouard Branly, it consisted of a tube or capsule containing two electrodes spaced a...

 with telephone
Telephone
The telephone , colloquially referred to as a phone, is a telecommunications device that transmits and receives sounds, usually the human voice. Telephones are a point-to-point communication system whose most basic function is to allow two people separated by large distances to talk to each other...

 detector
" in a paper presented at the Royal Society
Royal Society
The Royal Society of London for Improving Natural Knowledge, known simply as the Royal Society, is a learned society for science, and is possibly the oldest such society in existence. Founded in November 1660, it was granted a Royal Charter by King Charles II as the "Royal Society of London"...

, London. Later he received , "Detector for electrical disturbances" (1904), for a specific electromagnetic receiver. Bose would continue research and made other contributuions to the development of radio.

Rutherford


The New Zealander Ernest Rutherford, 1st Baron Rutherford of Nelson contributed to the development of radio. In 1895 he was awarded an Exhibition of 1851 Science Research Scholarship to Cambridge. He arrived in England with a reputation as an innovator and inventor, and distinguished himself in several fields, initially by working out the electrical properties of solids and then using wireless waves as a method of signalling. Rutherford was encouraged in his work by Sir Robert Ball, who had been scientific adviser to the body maintaining lighthouse
Lighthouse
A lighthouse is a tower, building, or other type of structure designed to emit light from a system of lamps and lenses or, in older times, from a fire, and used as an aid to navigation for maritime pilots at sea or on inland waterways....

s on the Irish coast; he wished to solve the difficult problem of a ship's inability to detect a lighthouse in fog. Sensing fame and fortune, Rutherford increased the sensitivity of his apparatus until he could detect electromagnetic waves via his electromagnetic receiver over a distance of several hundred meters. The hysteresis magnetic detector invented by Rutherford, and described by him in 1897, was used to determine the characteristics of electromagnetic waves, the ends of the little solenoid of the detector being attached to the mercury cups of the slider. The development, though, of wireless technology was left for others, as Rutherford continued purely scientific research. J. J. Thomson
J. J. Thomson
Sir Joseph John "J. J." Thomson, OM, FRS was a British physicist and Nobel laureate. He is credited for the discovery of the electron and of isotopes, and the invention of the mass spectrometer...

 realized that Rutherford was a researcher of ability and invited him to join in a study of the electrical conduction of gases.

Braun


Ferdinand Braun's major contributions were the introduction of a closed tuned circuit in the generating part of the transmitter, and its separation from the radiating part (the antenna) by means of inductive coupling, and later on the usage of crystals for receiving purposes. Braun experimented at first at the University of Strassbourg. Braun had written extensively on wireless subjects and was well known through his many contributions to the Electrician and other scientific journals. In 1899, he would apply for the patents, Electro telegraphy by means of condensers and induction colls and Wireless electro transmission of signals over surfaces.

Pioneers working on wireless devices eventually came to a limit of distance they could cover. Connecting the antenna directly to the spark gap produced only a heavily damped pulse train. There were only a few cycles before oscillations ceased. Braun's circuit afforded a much longer sustained oscillation because the energy encountered less loss swinging between coil and Leyden Jars. Also, by means of inductive antenna coupling the radiator was matched to the generator.

In spring 1899 Braun, accompanied by his colleagues Cantor and Zenneck, went to Cuxhaven to continue their experiments at the North Sea. On February 6, 1899, he would apply for the United States Patent, . Not before long he bridged a distance of 42 km to the city of Mutzing. On 24 September 1900 radio telegraphy signals were exchanged regularly with the island of Heligoland over a distance of 62 km. Lightvessels in the river Elbe and a coast station at Cuxhaven commenced a regular radio telegraph service. On August 6, 1901, he would apply for .

By 1904, the closed circuit system of wireless telegraphy, connected with the name of Braun, was well known and generally adopted in principle. The results of Braun's experiments, published in the Electrician, possess interest, apart from the method employed. Braun showed how the problem could be satisfactorily and economically solved. The closed circuit oscillator has the advantage, as was known, of being able to draw upon the kinetic energy in the oscillator circuit, and thus, owing to the fact that such a circuit can be given a much greater capacity than can be obtained with a radiating aerial alone, much more energy can be stored up and radiated by its employment. The emission is also prolonged, both results tending towards the attainment of the much desired train of undamped waves. The energy available, though greater than with the open system, was still inconsiderable unless very high potentials, with the attendant drawbacks, were used. Braun avoided the use of extremely high potentials for charging the gap and also makes use of a less wasteful gap by sub-dividing it. The chief point in his new arrangement, however, is not the sub-division of the gap merely but their arrangement, by which they are charged in parallel, at low voltages, and discharge in series. The Nobel Prize
Nobel Prize
The Nobel Prizes are annual international awards bestowed by Scandinavian committees in recognition of cultural and scientific advances. The will of the Swedish chemist Alfred Nobel, the inventor of dynamite, established the prizes in 1895...

 awarded to Braun in 1909 depicts this design.

Later radio development




Popov


During the Chicago World's Columbian Exhibition and the Third International Electrical Congress, Alexander Stepanovich Popov of Kronstadt, Russia
Kronstadt
Kronstadt , also spelled Kronshtadt, Cronstadt |crown]]" and Stadt for "city"); is a municipal town in Kronshtadtsky District of the federal city of St. Petersburg, Russia, located on Kotlin Island, west of Saint Petersburg proper near the head of the Gulf of Finland. Population: It is also...

 was a representative of the Russian Torpedo School. Afterward, he worked on his wireless designs. Popov conducted experiments along the lines of Hertz's research. In 1894-95 he built his first radio receiver, an improved version of coherer
Coherer
The coherer was a primitive form of radio signal detector used in the first radio receivers during the wireless telegraphy era at the beginning of the twentieth century. Invented around 1890 by French scientist Édouard Branly, it consisted of a tube or capsule containing two electrodes spaced a...

-based design by Oliver Lodge. In 1895, he built a coherer
Coherer
The coherer was a primitive form of radio signal detector used in the first radio receivers during the wireless telegraphy era at the beginning of the twentieth century. Invented around 1890 by French scientist Édouard Branly, it consisted of a tube or capsule containing two electrodes spaced a...

. Popov constructed a filings coherer, one form of which was used in some surveying experiments by the Russian government. He used early in 1895, the coherer auto-tapping mechanism, and substituted for the galvanometer an ordinary telegraphic relay. He operated this apparatus at a distance by means of a large radiator. One terminal of his coherer was connected to a conductor fastened to a mast about 30 ft. high on the top of the Institute building and the other terminal of the coherer was grounded.

Popov presented his radio receiver to the Russian Physical and Chemical Society on May 7, 1895 — the day has been celebrated in the Russian Federation as "Radio Day
Radio Day
Radio Day , Communications Workers' Day or Radio and Television Day is a commemoration of the development of radio in Russia...

". On this day, Popov performed a public demonstration of transmission and reception of radio waves used for communication at the Russian Physical and Chemical Society, using his coherer. The paper on his findings was published the same year (December 15, 1895). Popov had recorded, at the end of 1895, that he was hoping for distant signaling with radio waves. He did not apply for a patent for this invention. Popov's early experiments were transmissions of only 600 yards (548.6 m). Popov was the first to develop a practical communication system based on the coherer, and is usually considered by the Russians to have been the inventor of radio.

In 1895-96 Popov and others utilized the coherer to show the existence of atmospheric electricity, using for the purpose a vertical wire attached to the coherer. On March 24, 1896, Popov demonstrated in public the transmission of radio waves, between different campus buildings, to the Saint Petersburg
Saint Petersburg
Saint Petersburg is a city and a federal subject of Russia located on the Neva River at the head of the Gulf of Finland on the Baltic Sea...

 Physical Society. (This was before the public demonstration of the Marconi system around September 1896.) Per other accounts, however, Popov achieved these results only in December 1897—that is, after publication of Marconi's patent. In 1898 his signal was received 6 miles (9.7 km) away, and in 1899 130 miles (209.2 km) away.

His receiver proved to be able to sense lightning strikes at distances of up to 30 km, thus functioning as a lightning detector
Lightning detector
A lightning detector is a device that detects lightning produced by thunderstorms. There are three primary types of detectors: ground-based systems using multiple antennas, mobile systems using a direction and a sense antenna in the same location , and space-based systems.The device was invented in...

. In late 1895, Popov built a version of the receiver that was capable of automatically recording lightning strikes on paper rolls. Popov's system was eventually extended to function as a wireless telegraph, with a Morse key attached to the transmitter. There's some dispute regarding the first public test of this design. It is frequently stated that Popov used his radio to send a Morse code message over a distance of 250 m in 26 March 1896 (three months before Marconi's patent was filed). However, contemporary confirmations of this transmission are lacking. It is more likely that said experiment took place in December 1897.

In 1900, Popov stated at the Congress of Russian Electrical Engineers that, "the emission and reception of signals by Marconi by means of electric oscillations was nothing new, as in America Nikola Tesla
Nikola Tesla
Nikola Tesla was a Serbian-American inventor, mechanical engineer, and electrical engineer...

 did the same experiments in 1893
." Also in 1900, a radio station was established under Popov's instructions on Hogland
Hogland
Gogland or Hogland is an island in the Gulf of Finland of the Baltic Sea, located some 180 km west of Saint Petersburg and 35 km away from the coast of Finland . The island is a part of the Leningrad Oblast, Russia. The area of Hogland Island is approximately...

 island (Suursaari) to provide two-way communication by wireless telegraphy between the Russian naval base and the crew of the battleship General-Admiral Apraksin. By February 5 messages were being received reliably. The wireless messages were relayed to Hogland Island by a station some 25 miles (40.2 km) away at Kymi (nowadays Kotka
Kotka
Kotka is a town and municipality of Finland. Its former name is Rochensalm.Kotka is located on the coast of the Gulf of Finland at the mouth of Kymi River and it is part of the Kymenlaakso region in southern Finland. The municipality has a population of and covers an area of of which is water....

) on the Finnish
Grand Duchy of Finland
The Grand Duchy of Finland was the predecessor state of modern Finland. It existed 1809–1917 as part of the Russian Empire and was ruled by the Russian czar as Grand Prince.- History :...

 coast. Later Popov experimented with ship-to-shore communication. Popov died in 1905 and his claim was not pressed by the Russian government until 1945.

Baviera


In May–June 1899, Julio Cervera Baviera
Julio Cervera Baviera
Julio Cervera Baviera was a Spanish engineer, pioneer in the development of radio, educator, explorer, and military man. He also authored various scientific and geographic books and articles.-Education:...

 worked to develop his own system. After visiting Marconi’s radiotelegraphic installations on the English Channel, he began collaborating with Marconi on resolving the problem of a wireless communication system, obtaining some patents by the end of 1899. Cervera, who worked with Marconi and his assistant, George S. Kemp, in 1899, resolved the issues with their wireless telegraph. He obtained his first patents prior to the end of that year.

Marconi


Guglielmo Marconi
Guglielmo Marconi
Guglielmo Marconi was an Italian inventor, known as the father of long distance radio transmission and for his development of Marconi's law and a radio telegraph system. Marconi is often credited as the inventor of radio, and indeed he shared the 1909 Nobel Prize in Physics with Karl Ferdinand...

 studied at the Leghorn Technical School, and acquainted himself with the published writings of Professor Augusto Righi
Augusto Righi
Augusto Righi was an Italian physicist and a pioneer in the study of electromagnetism. He was born and died in Bologna.His early research, conducted in Bologna between 1872 and 1880, was primarily in electrostatics...

 of the University of Bologna
University of Bologna
The Alma Mater Studiorum - University of Bologna is the oldest continually operating university in the world, the word 'universitas' being first used by this institution at its foundation. The true date of its founding is uncertain, but believed by most accounts to have been 1088...

. In 1894, Sir William Preece deliver a paper to the Royal Institution in London on electric signalling without wires. In 1894 at the Royal Institution lectures, Lodge delivers "The Work of Hertz and Some of His Successors". Marconi is said to have read, while on vacation in 1894, about the experiments that Hertz did in the 1880s. Marconi also read about Tesla's work. It was at this time that Marconi began to understand that radio waves could be used for wireless communications. Marconi's early apparatus was a development of Hertz’s laboratory apparatus into a system designed for communications purposes. At first Marconi used a transmitter to ring a bell in a receiver in his attic laboratory. He then moved his experiments out-of-doors on the family estate near Bologna, Italy, to communicate further. He replaced Hertz’s vertical dipole with a vertical wire topped by a metal sheet, with an opposing terminal connected to the ground. On the receiver side, Marconi replaced the spark gap with a metal powder coherer, a detector developed by Edouard Branly
Edouard Branly
Édouard Eugène Désiré Branly was a French inventor, physicist and professor at the Institut Catholique de Paris. He is primarily known for his early involvement in wireless telegraphy and his invention of the Branly coherer around 1890.-Biography:The coherer was the first widely used detector for...

 and other experimenters. Marconi transmitted radio signals for about 1 miles (1.6 km) at the end of 1895.

By 1896, Marconi introduced to the public a device in London
London
London is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...

, asserting it was his invention. Despite Marconi's statements to the contrary, though, the apparatus resembles Tesla's descriptions in his research, demonstrations and patents. Marconi's later practical four-tuned system was pre-dated by N. Tesla, Oliver Lodge, and J. S. Stone. He filed a patent on his earliest system with the British Patent Office on June 2, 1896.

Marconi was awarded a patent for radio with British patent No. 12,039, Improvements in Transmitting Electrical Impulses and Signals and in Apparatus There-for. The complete specification was filed March 2, 1897. This was Marconi's initial patent for the radio, though it used various earlier techniques of various other experimenters (primarily Tesla) and resembled the instrument demonstrated by others (including Popov). During this time spark-gap wireless telegraphy was widely researched. In July, 1896, Marconi got his invention and new method of telegraphy to the attention of Preece, then engineer-in-chief to the British Government Telegraph Service, who had for the previous twelve years interested himself in the development of wireless telegraphy by the inductive-conductive method. On June 4, 1897, he delievers "Signalling through Space without Wires". Preece devoted considerable time to exhibiting and explaining the Marconi apparatus at the Royal Institution
Royal Institution
The Royal Institution of Great Britain is an organization devoted to scientific education and research, based in London.-Overview:...

 in London, stating that Marconi invented a new relay which had high sensitiveness and delicacy.
In 1896, Bose went to London on a lecture tour and met Marconi, who was conducting wireless experiments for the British post office. The Marconi Company Ltd. was founded by Marconi in 1897, known as the Wireless Telegraph Trading Signal Company. Also in 1897, Marconi established the radio station at Niton, Isle of Wight
Niton, Isle of Wight
Niton is a village on the Isle of Wight, near Ventnor with a thriving population of 1142, supporting two pubs, several churches,a pottery workshop/shop, a pharmacy and 3 local shops including a post office...

, England. Marconi's wireless telegraphy was inspected by the Post Office Telegraph authorities; they made a series of experiments with Marconi's system of telegraphy without connecting wires, in the Bristol Channel
Bristol Channel
The Bristol Channel is a major inlet in the island of Great Britain, separating South Wales from Devon and Somerset in South West England. It extends from the lower estuary of the River Severn to the North Atlantic Ocean...

. The October wireless signals of 1897 were sent from Salisbury Plain
Salisbury Plain
Salisbury Plain is a chalk plateau in central southern England covering . It is part of the Southern England Chalk Formation and largely lies within the county of Wiltshire, with a little in Hampshire. The plain is famous for its rich archaeology, including Stonehenge, one of England's best known...

 to Bath, a distance of 34 miles (54.7 km). Marconi's reputation is largely based on the making of his law
Marconi's law
Marconi's law is the relation between height of antennae and maximum signalling distance. Guglielmo Marconi enunciated at one time an empirical law that, for simple vertical sending and receiving antennae of equal height, the maximum working telegraphic distance varied as the square of the height...

 (1897), and other accomplishments in radio communications and commercializing a practical system.

Other experimental stations were established at Lavernock Point, near Penarth
Penarth
Penarth is a town and seaside resort in the Vale of Glamorgan , Wales, 5.2 miles south west from the city centre of the Welsh capital city of Cardiff and lying on the north shore of the Severn Estuary at the southern end of Cardiff Bay...

; on the Flat Holmes, an island in mid-channel, and at Brean Down
Brean Down
Brean Down is a promontory off the coast of Somerset standing high and extending into the Bristol Channel at the eastern end of Bridgwater Bay between Weston-super-Mare and Burnham-on-Sea....

, a promontory
Promontory
Promontory may refer to:*Promontory, a prominent mass of land which overlooks lower lying land or a body of water*Promontory, Utah, the location where the United States first Transcontinental Railroad was completed...

 on the Somerset
Somerset
The ceremonial and non-metropolitan county of Somerset in South West England borders Bristol and Gloucestershire to the north, Wiltshire to the east, Dorset to the south-east, and Devon to the south-west. It is partly bounded to the north and west by the Bristol Channel and the estuary of the...

 side. Signals were obtained between the first and last-named points, a distance of, approximately, 8 miles (12.9 km). The receiving instrument used was a Morse inkwriter of the Post Office pattern. In 1898, Marconi opened a radio factory in Hall Street, Chelmsford, England, employing around 50 people. In 1899, Marconi announced his invention of the "iron-mercury-iron coherer with telephone detector" in a paper presented at Royal Society, London.

In May, 1898, communication was established for the Corporation of Lloyds
Lloyd's of London
Lloyd's, also known as Lloyd's of London, is a British insurance and reinsurance market. It serves as a partially mutualised marketplace where multiple financial backers, underwriters, or members, whether individuals or corporations, come together to pool and spread risk...

 between Ballycastle
Ballycastle, County Antrim
Ballycastle is a small town in County Antrim in Northern Ireland. Its population was 5,089 people in the 2001 Census. It is the seat and main settlement of Moyle District Council....

 and the Lighthouse
Lighthouse
A lighthouse is a tower, building, or other type of structure designed to emit light from a system of lamps and lenses or, in older times, from a fire, and used as an aid to navigation for maritime pilots at sea or on inland waterways....

 on Rathlin Island
Rathlin Island
Rathlin Island is an island off the coast of County Antrim, and is the northernmost point of Northern Ireland. Rathlin is the only inhabited offshore island in Northern Ireland, with a rising population of now just over 100 people, and is the most northerly inhabited island off the Irish coast...

 in the North of Ireland. In July, 1898, the Marconi telegraphy was employed to report the results of yacht races at the Kingston Regatta
Kingston Regatta
Kingston Regatta is a rowing regatta, on the River Thames in England which takes place at Kingston upon Thames, Surrey on the reach above Teddington Lock....

 for the Dublin Express
Daily Express (Dublin)
The Daily Express of Dublin was an Irish newspaper published from 1851 until June 1921, and then continued for registration purposes until 1960.It was a unionist newspaper. From 1917, its title was the Daily Express and Irish Daily Mail...

 newspaper. A set of instruments were fitted up in a room at Kingstown, and another on board a steamer, the Flying Huntress. The aerial conductor on shore was a strip of wire netting attached to a mast 40 feet (12.2 m) high, and several hundred messages were sent and correctly received during the progress of the races.

At this time His Majesty King Edward VII, then Prince of Wales
Prince of Wales
Prince of Wales is a title traditionally granted to the heir apparent to the reigning monarch of the United Kingdom of Great Britain and Northern Ireland and the 15 other independent Commonwealth realms...

, had the misfortune to injure his knee, and was confined on board the royal yacht Osltorm in Cowes Bay.
Marconi fitted up his apparatus on board the royal yacht by request, and also at Osborne House
Osborne House
Osborne House is a former royal residence in East Cowes, Isle of Wight, UK. The house was built between 1845 and 1851 for Queen Victoria and Prince Albert as a summer home and rural retreat....

, Isle of Wight, and kept up wireless communication for three weeks between these stations. The distances covered were small; but as the yacht moved about, on some occasions high hills were interposed, so that the aerial wires were overtopped by hundreds of feet, yet this was no obstacle to communication. These demonstrations led the Corporation of Trinity House to afford an opportunity for testing the system in practice between the South Foreland Lighthouse
South Foreland Lighthouse
South Foreland Lighthouse is a Victorian lighthouse on the South Foreland in St. Margaret's Bay, Dover, Kent, England, used to warn ships approaching the nearby Goodwin Sands. It went out of service in 1988 and is currently owned by the National Trust...

, near Dover, and the East Goodwin Lightship, on the Goodwin Sands
Goodwin Sands
The Goodwin Sands is a 10-mile-long sand bank in the English Channel, lying six miles east off Deal in Kent, England. The Brake Bank lying shorewards is part of the same geological unit. As the shoals lie close to major shipping channels, more than 2,000 ships are believed to have been wrecked...

. This installation was set in operation on December 24, 1898, and proved to be of value. It was shown that when once the apparatus was set up it could be worked by ordinary seamen with very little training.

At the end of 1898 electric wave telegraphy established by Marconi had demonstrated its utility, especially for communication between ship and ship and ship and shore. Electric wave telegraphy had the advantages as follows:
  • Transmission worked as well by night as by day, and in bad weather, fogs, or storms, as well as in fair weather; provided that the proper insulation of the aerial wire or elevated conductor was maintained.
  • In certain electrical conditions of the atmosphere, and during thunderstorms, some difficulty was usually found in working, owing to the atmospheric discharges affecting the sensitive tube, and therefore making stray marks on the Morse tape of the printer, but seldom sufficient to interrupt communication altogether.
  • The interposition of high hills, trees, or the curvature of the earth did not prevent communication, though slightly affecting the power required. It worked particularly well over sea surface, and between ships and shore stations.
  • The apparatus could be set up and handled by any ordinary telegraphist, and the record was made on paper strip in the usual Morse code.
  • Transmission easily covered distances far beyond those feasible or attained by other systems of wireless telegraphy.
  • Lastly, the apparatus required was by no means costly, and, with the exception of the mast required for upholding the aerial wire, it occupied but little space, and was particularly adapted for use on board ship.


The Haven Hotel
Haven Hotel
The Haven Hotel is an AA four star hotel in Sandbanks, near Poole, Dorset on the south coast of England.-History:The first hotel built on this location was the North Haven Inn in 1838. The Inn was demolished and replaced with the present Haven Hotel in 1887...

 station and Wireless Telegraph Mast was where much of Marconi's research work on wireless telegraphy was carried out after 1898. In 1899, he transmitted messages across the English Channel
English Channel
The English Channel , often referred to simply as the Channel, is an arm of the Atlantic Ocean that separates southern England from northern France, and joins the North Sea to the Atlantic. It is about long and varies in width from at its widest to in the Strait of Dover...

. Also in 1899, Marconi delivered "Wireless Telegraphy" to the Institution of Electrical Engineers
Institution of Electrical Engineers
The Institution of Electrical Engineers was a British professional organisation of electronics, electrical, manufacturing, and Information Technology professionals, especially electrical engineers. The I.E.E...

. In addition, in 1899, W. H. Preece delivers "Aetheric Telegraphy", stating that the experimental stage in wireless telegraphy had been passed in 1894 and inventors were then entering the commercial stage. Preece, continuing in the lecture, details the work of Marconi and other British inventors. In October, 1899, the progress of the yachts in the international race
America's Cup
The America’s Cup is a trophy awarded to the winner of the America's Cup match races between two yachts. One yacht, known as the defender, represents the yacht club that currently holds the America's Cup and the second yacht, known as the challenger, represents the yacht club that is challenging...

 between the Columbia and Shamrock was successfully reported by aerial telegraphy, as many as 4,000 words having been (as is said) despatched from the two ship stations to the shore stations. Immediately afterward the apparatus was placed by request at the service of the United States Navy Board, and some highly interesting experiments followed under Marconi's personal supervision. The Marconi Company was renamed Marconi's Wireless Telegraph Company in 1900.


In 1901, Marconi claimed to have received daytime transatlantic radio frequency signals at a wavelength of 366 metres
Medium frequency
Medium frequency refers to radio frequencies in the range of 300 kHz to 3 MHz. Part of this band is the medium wave AM broadcast band. The MF band is also known as the hectometer band or hectometer wave as the wavelengths range from ten down to one hectometers...

 (820 kHz). Marconi established a wireless transmitting station at Marconi House, Rosslare Strand, Co. Wexford in 1901 to act as a link between Poldhu in Cornwall and Clifden in Co. Galway. His announcement on 12 December 1901, using a 152.4 metres (500 ft) kite-supported antenna for reception, stated a the message was received at Signal Hill in St John's
St. John's, Newfoundland and Labrador
St. John's is the capital and largest city in Newfoundland and Labrador, and is the oldest English-founded city in North America. It is located on the eastern tip of the Avalon Peninsula on the island of Newfoundland. With a population of 192,326 as of July 1, 2010, the St...

, Newfoundland
Newfoundland and Labrador
Newfoundland and Labrador is the easternmost province of Canada. Situated in the country's Atlantic region, it incorporates the island of Newfoundland and mainland Labrador with a combined area of . As of April 2011, the province's estimated population is 508,400...

 (now part of Canada) via signals transmitted by the company's new high-power station at Poldhu
Poldhu
Poldhu is a small area in south Cornwall, England, UK, situated on the Lizard Peninsula; it comprises Poldhu Point and Poldhu Cove. It lies on the coast west of Goonhilly Downs, with Mullion to the south and Porthleven to the north...

, Cornwall
Cornwall
Cornwall is a unitary authority and ceremonial county of England, within the United Kingdom. It is bordered to the north and west by the Celtic Sea, to the south by the English Channel, and to the east by the county of Devon, over the River Tamar. Cornwall has a population of , and covers an area of...

. The message received was the Morse letter 'S' - three dots. Bradford has recently contested this, however, based on theoretical work as well as a reenactment of the experiment; it is possible that what was heard was only random atmospheric noise, which was mistaken for a signal, or that Marconi may have heard a shortwave
Shortwave
Shortwave radio refers to the upper MF and all of the HF portion of the radio spectrum, between 1,800–30,000 kHz. Shortwave radio received its name because the wavelengths in this band are shorter than 200 m which marked the original upper limit of the medium frequency band first used...

 harmonic
Harmonic
A harmonic of a wave is a component frequency of the signal that is an integer multiple of the fundamental frequency, i.e. if the fundamental frequency is f, the harmonics have frequencies 2f, 3f, 4f, . . . etc. The harmonics have the property that they are all periodic at the fundamental...

 of the signal. The distance between the two points was about 3500 kilometres (2,174.8 mi).

The Poldhu
Poldhu
Poldhu is a small area in south Cornwall, England, UK, situated on the Lizard Peninsula; it comprises Poldhu Point and Poldhu Cove. It lies on the coast west of Goonhilly Downs, with Mullion to the south and Porthleven to the north...

 to Newfoundland transmission claim has been criticized. There are various science historians, such as Belrose and Bradford, who have cast doubt that the Atlantic was bridged in 1901, but other science historians have taken the position that this was the first transatlantic radio transmission. Critics have claimed that it is more likely that Marconi received stray atmospheric noise from atmospheric electricity
Atmospheric electricity
Atmospheric electricity is the regular diurnal variations of the Earth's atmospheric electromagnetic network . The Earth's surface, the ionosphere, and the atmosphere is known as the global atmospheric electrical circuit...

 in this experiment. The transmitting station in Poldhu, Cornwall used a spark-gap transmitter that could produce a signal in the medium frequency range and with high power levels.

Marconi transmitted from England to Canada and the United States. In this period, a particular electromagnetic receiver, called the Marconi magnetic detector or hysteresis magnetic detector, was developed further by Marconi and was successfully used in his early transatlantic work (1902) and in many of the smaller stations for a number of years. In 1902, a Marconi station
Marconi Station
The Marconi Wireless Corporation operated numerous pioneering radio stations in Canada, Ireland, Newfoundland, the United States, the United Kingdom and a number of other locations around the world.-Australia:...

 was established in the village of Crookhaven
Crookhaven
Crookhaven is a village in County Cork, Ireland, on the most southwestern tip of Ireland. A winter population of about forty swells in the summer to about four hundred with the occupants of the many holiday homes arriving.-History:...

, County Cork
County Cork
County Cork is a county in Ireland. It is located in the South-West Region and is also part of the province of Munster. It is named after the city of Cork . Cork County Council is the local authority for the county...

, Ireland
Ireland
Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...

 to provide marine radio communications to ships arriving from the Americas. A ship's master could contact shipping line agents ashore to enquire which port was to receive their cargo without the need to come ashore at what was the first port of landfall. Ireland was also, due to its western location, to play a key role in early efforts to send trans-Atlantic messages. Marconi transmitted from his station in Glace Bay, Nova Scotia, Canada across the Atlantic, and on 18 January 1903 a Marconi station sent a message of greetings from Theodore Roosevelt
Theodore Roosevelt
Theodore "Teddy" Roosevelt was the 26th President of the United States . He is noted for his exuberant personality, range of interests and achievements, and his leadership of the Progressive Movement, as well as his "cowboy" persona and robust masculinity...

, the President of the United States, to the King of the United Kingdom, marking the first transatlantic radio transmission originating in the United States

In 1904, Marconi opened the ocean daily newspaper, the Cunard Daily Bulletin, on the R.M.S.
Royal Mail Ship
Royal Mail Ship , usually seen in its abbreviated form RMS, a designation which dates back to 1840, is the ship prefix used for seagoing vessels that carry mail under contract by Royal Mail...

 "Campania
RMS Campania
RMS Campania was a British ocean liner owned by the Cunard Steamship Line Shipping Company, built by Fairfield Shipbuilding and Engineering Company of Govan, Scotland, and launched on Thursday, 8 September 1891....

." At the start, the passing events were printed in a little pamphlet of four pages called the Cunard Bulletin. The title would read Cunard Daily Bulletin, with subheads for "Marconigrams Direct to the Ship." All the passenger ships of the Cunard Company are fitted with Marconi's system of wireless telegraphy, by means of which constant communication was kept up, either with other ships or with land stations on the eastern or western hemisphere. The RMS Lucania
RMS Lucania
RMS Lucania was a British ocean liner owned by the Cunard Steamship Line Shipping Company, built by Fairfield Shipbuilding and Engineering Company of Govan, Scotland, and launched on Thursday, 2 February 1893....

, Oct., 1903, with Marconi on board, was the first vessel to hold communication with both sides of the Atlantic. The Cunard Daily Bulletin, a thirty-two page illustrated paper published on board these boats, recorded news received by wireless telegraphy, and is first ocean newspaper. In August, 1903, in agreement was made with the British Government by which the Cunard Co. were to build two steamers, to be, with all other Cunard ships, at the disposal of the British Admiralty for hire or purchase whenever they may be required, the Government lending the company £2,600,000 to build the ships and granting them a subsidy £150,000 a year. One was the RMS Lusitania
RMS Lusitania
RMS Lusitania was a British ocean liner designed by Leonard Peskett and built by John Brown and Company of Clydebank, Scotland. The ship entered passenger service with the Cunard Line on 26 August 1907 and continued on the line's heavily-traveled passenger service between Liverpool, England and New...

 and the RMS Mauritania
RMS Mauretania (1906)
RMS Mauretania was an ocean liner designed by Leonard Peskett and built by Swan, Hunter & Wigham Richardson at Wallsend, Tyne and Wear for the British Cunard Line, and launched on 20 September 1906. At the time, she was the largest and fastest ship in the world. Mauretania became a favourite among...

.

In June and July 1923, Marconi's shortwave
Shortwave
Shortwave radio refers to the upper MF and all of the HF portion of the radio spectrum, between 1,800–30,000 kHz. Shortwave radio received its name because the wavelengths in this band are shorter than 200 m which marked the original upper limit of the medium frequency band first used...

 transmissions were completed during nights on 97 meters from Poldhu Wireless Station
Poldhu
Poldhu is a small area in south Cornwall, England, UK, situated on the Lizard Peninsula; it comprises Poldhu Point and Poldhu Cove. It lies on the coast west of Goonhilly Downs, with Mullion to the south and Porthleven to the north...

, Cornwall
Cornwall
Cornwall is a unitary authority and ceremonial county of England, within the United Kingdom. It is bordered to the north and west by the Celtic Sea, to the south by the English Channel, and to the east by the county of Devon, over the River Tamar. Cornwall has a population of , and covers an area of...

, to his yacht Elettra in the Cape Verde Islands
Cape Verde
The Republic of Cape Verde is an island country, spanning an archipelago of 10 islands located in the central Atlantic Ocean, 570 kilometres off the coast of Western Africa...

. In September 1924, Marconi transmitted during daytime and nighttime on 32 meters from Poldhu to his yacht in Beirut
Beirut
Beirut is the capital and largest city of Lebanon, with a population ranging from 1 million to more than 2 million . Located on a peninsula at the midpoint of Lebanon's Mediterranean coastline, it serves as the country's largest and main seaport, and also forms the Beirut Metropolitan...

. Marconi, in July 1924, entered into contracts with the British General Post Office (GPO) to install telegraphy circuits from London to Australia, India, South Africa and Canada as the main element of the Imperial Wireless Chain
Imperial Wireless Chain
The Imperial Wireless Chain, also known as the Empire Wireless Chain, was a strategic international wireless telegraphy communications network, created to link the countries of the British Empire. Although the idea was conceived prior to World War I, Britain was the last of the world's Great Powers...

. The UK-to-Canada shortwave "Beam Wireless Service" went into commercial operation on 25 October 1926. Beam Wireless Services from the UK to Australia, South Africa and India went into service in 1927. Electronic components for the system were built at Marconi's New Street wireless factory in Chelmsford
Chelmsford
Chelmsford is the county town of Essex, England and the principal settlement of the borough of Chelmsford. It is located in the London commuter belt, approximately northeast of Charing Cross, London, and approximately the same distance from the once provincial Roman capital at Colchester...

.

Marconi would jointly receive the 1909 Nobel Prize in Physics
Nobel Prize in Physics
The Nobel Prize in Physics is awarded once a year by the Royal Swedish Academy of Sciences. It is one of the five Nobel Prizes established by the will of Alfred Nobel in 1895 and awarded since 1901; the others are the Nobel Prize in Chemistry, Nobel Prize in Literature, Nobel Peace Prize, and...

 with Karl Ferdinand Braun
Karl Ferdinand Braun
Karl Ferdinand Braun was a German inventor, physicist and Nobel laureate in physics. Braun contributed significantly to the development of the radio and television technology: he shared with Guglielmo Marconi the 1909 Nobel Prize in Physics.-Biography:Braun was born in Fulda, Germany, and...

 for contributions to the existing radio sciences. Marconi's demonstrations of the use of radio for wireless communications, equipping ships with life saving wireless communications, establishing the first transatlantic radio service, and building the first stations for the British short wave service, have marked his place in history. Shortly after the turn of the 20th century, the US Patent Office re-awarded Marconi a patent for radio. The was granted on June 4, 1901. Marconi's was awarded on June 11, 1901, also. This system was more advanced than his previous works. In 1943, a lawsuit regarding Marconi's early United States radio patents were resolved by the United States Supreme Court, who overturned most of these.

Naval wireless


The United States Navy Board had issued a 1899 report on the results of investigations of the Marconi system of wireless telegraphy. The report, Notes On The Marconi Wireless Telegraphy was published in full in the Electrician, and from it the following statements concerning the efficiency of the system have been taken: It was well adapted for use in squadron signalling under conditions of rain, fog, darkness and motion of speed. Wind, rain, fog, and other conditions of weather do not affect the transmission through space, but dampness may reduce the range, rapidity, and accuracy by impairing the insulation of the aerial wire and the instruments. Darkness has no effect. When two transmitters are sending at the same time, all the receiving wires within range receive the impulses from transmitters, and the tapes, although unreadable, show unmistakably that such double sending was taking place. In every case, under a great number of varied conditions, the attempted interference was complete. Marconi, although he stated to the Board before these attempts were made that he could prevent interference, never explained how nor made any attempt to demonstrate that it could be done. Between large ships (heights of masts 130 feet (39.6 m) and 140 feet (42.7 m)) and a torpedo-boat (height of mast 45 feet (13.7 m)), across open water, signals can be read up to 7 miles (11.3 km) on the torpedo-boat and 85 miles (136.8 km) on the ship
Naval ship
A naval ship is a ship used for combat purposes, commonly by a navy. Naval ships are differentiated from civilian ships by construction and purpose...

. Communication might be interrupted altogether when tall buildings of iron framing intervene. The rapidity was not greater than twelve words per minute for skilled operators. The sending apparatus and wire would injuriously affect the compass if placed near it. The exact distance were not known, and would be determined by experiment. The system was adapted for use on all vessels of the navy, including torpedo-boats and small vessels, as patrol boat
Patrol boat
A patrol boat is a relatively small naval vessel generally designed for coastal defense duties.There have been many designs for patrol boats. They may be operated by a nation's navy, coast guard, or police force, and may be intended for marine and/or estuarine or river environments...

s, scout boats, and despatch boats, but it was impracticable in a small boat. For landing parties the only feasible method of use would be to erect a pole on shore
Antenna (radio)
An antenna is an electrical device which converts electric currents into radio waves, and vice versa. It is usually used with a radio transmitter or radio receiver...

 and then communicate with the ship. The system could be adapted to the telegraphic determination of differences of longitude
Longitude
Longitude is a geographic coordinate that specifies the east-west position of a point on the Earth's surface. It is an angular measurement, usually expressed in degrees, minutes and seconds, and denoted by the Greek letter lambda ....

 in surveying
Surveying
See Also: Public Land Survey SystemSurveying or land surveying is the technique, profession, and science of accurately determining the terrestrial or three-dimensional position of points and the distances and angles between them...

. The Board respectfully recommended that the system be given a trial in the United States Navy
United States Navy
The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...

.

The HMS Hector
HMS Hector (1862)
HMS Hector was the lead ship of the armoured frigates ordered by the Royal Navy in 1861. Upon completion in 1864 she was assigned to the Channel Fleet. The ship was paid off in 1867 to refit and be re-armed. Upon recommissioning in 1868 she was assigned as the guard ship of the Fleet Reserve in...

became the first British warship to have wireless telegraphy
Wireless telegraphy
Wireless telegraphy is a historical term used today to apply to early radio telegraph communications techniques and practices, particularly those used during the first three decades of radio before the term radio came into use....

 installed when she conducted the first trials of the new equipment for the Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

. Starting in December 1899, the HMS Hector and HMS Jaseur were outfitted with wireless equipment. In 1901, HMS Jaseur
HMS Jaseur
Six ships of the Royal Navy have borne the name HMS Jaseur, the name coming from the French for the Waxwing. was a 12-gun brig-sloop that captured off the Andaman Islands in 1807. was a Cruizer-class brig-sloop launched in 1813 and sold in 1847. was a wood screw gunboat launched in 1857 and...

 received signals from the Marconi transmitter on the Isle of Wight and from the HMS Hector (25 January).

Stone Stone


John Stone Stone
John Stone Stone
John Stone Stone was an American mathematician, physicist and inventor. He labored as an early telephone engineer, was influential in developing wireless communication technology, and holds dozens of key patents in the field of "space telegraphy".-Early years:Stone was born in Dover, now Manakin...

 labored as an early telephone engineer and was influential in developing wireless communication technology, and holds dozens of key patent
Patent
A patent is a form of intellectual property. It consists of a set of exclusive rights granted by a sovereign state to an inventor or their assignee for a limited period of time in exchange for the public disclosure of an invention....

s in the field of "space telegraphy". Patents of Stone for radio, together with their equivalents in other countries, form a very voluminous contribution to the patent literature of the subject. More than seventy United States patents have been granted to this patentee alone. In many cases these specifications are learned contributions to the literature of the subject, filled with valuable references to other sources of information. A complete analysis of Stone's specifications would occupy too much space. Broadly speaking, they may be divided into four classes:
  • Those concerned with proposed methods for the achievement of syntonic telegraphy, or the isolation of receiving stations or protection of receivers from the action of vagrant waves.
  • Those describing forms of electric wave detector or cymoscope.
  • Those covering the construction of various forms of transmitting
    Transmitter
    In electronics and telecommunications a transmitter or radio transmitter is an electronic device which, with the aid of an antenna, produces radio waves. The transmitter itself generates a radio frequency alternating current, which is applied to the antenna. When excited by this alternating...

     and receiving circuit
    Receiver (radio)
    A radio receiver converts signals from a radio antenna to a usable form. It uses electronic filters to separate a wanted radio frequency signal from all other signals, the electronic amplifier increases the level suitable for further processing, and finally recovers the desired information through...

    , and the production of continuous trains of wave
    Continuous wave
    A continuous wave or continuous waveform is an electromagnetic wave of constant amplitude and frequency; and in mathematical analysis, of infinite duration. Continuous wave is also the name given to an early method of radio transmission, in which a carrier wave is switched on and off...

    s.
  • Miscellaneous specifications covering devices proposed for localizing the direction of the arriving waves and other matters.


Stone has had issued to him a large number of patents embracing a method for impressing oscillations on a radiator system and emitting the energy in the form of waves of predetermined length whatever may be the electrical dimensions of the oscillator. On February 8, 1900, he filed for a selective system in . In this system, two simple circuits are associated inductively, each having an independent degree of freedom, and in which the restoration of electric oscillations to zero potential the currents are superimposed, giving rise to compound harmonic currents which permit the resonator system to be syntonized with precision to the oscillator. Stone's system, as stated in , developed free or unguided simple harmonic electromagnetic signal waves of a definite frequency to the exclusion of the energy of signal waves of other frequencies, and an elevated conductor and means for developing therein forced simple electric vibrations of corresponding frequency. In these patents Stone devised a multiple inductive oscillation circuit with the object of forcing on the antenna circuit a single oscillation of definite frequency. In the system for receiving the energy of free or unguided simple harmonic electromagnetic signal waves of a definite frequency to the exclusion of the energy of signal waves of other frequencies, he claimed an elevated conductor and a resonant circuit associated with said conductor and attuned to the frequency of the waves, the energy of which is to be received. A coherer made on what is called the Stone system was employed in some of the portable wireless outfits of the United States Army
United States Army
The United States Army is the main branch of the United States Armed Forces responsible for land-based military operations. It is the largest and oldest established branch of the U.S. military, and is one of seven U.S. uniformed services...

. The Stone Coherer has two small steel plugs between which are placed loosely packed carbon granules. This is a self-decohering device; though not as sensitive as other forms of detectors it is well suited to the rough usage of portable outfits.

Fessenden


In late 1886, Reginald A. Fessenden began working directly for Thomas Edison at the inventor's new laboratory in West Orange, New Jersey
West Orange, New Jersey
West Orange is a township in central Essex County, New Jersey, United States. As of the 2010 United States Census, the township population was 46,207...

. Fessenden quickly made major advances, especially in receiver design, as he worked to develop audio reception of signals. Fessenden's initial United States patents were and and are companion patents. One concerns the methods and the other the devices of the same system. The United States Weather Bureau began, early in 1900, a systematic course of experimentation in wireless telegraphy, employing him as a specialist. Fessenden evolved the heterodyne
Heterodyne
Heterodyning is a radio signal processing technique invented in 1901 by Canadian inventor-engineer Reginald Fessenden where high frequency signals are converted to lower frequencies by combining two frequencies. Heterodyning is useful for frequency shifting information of interest into a useful...

 principle here where two signals combined to produce a third audible tone.

In 1900, construction began on a large radio transmitting dynamo. Fessenden, experimenting with a high-frequency spark transmitter, successfully transmitted speech on December 23, 1900 over a distance of about 1.6 kilometre (0.994196378639691 mi), the first audio radio transmission. Early in 1901 the Weather Bureau officially installed Fessenden at Wier's Point, Roanoke Island
Roanoke Island
Roanoke Island is an island in Dare County near the coast of North Carolina, United States. It was named after the historical Roanoke Carolina Algonquian people who inhabited the area in the 16th century at the time of English exploration....

, North Carolina
North Carolina
North Carolina is a state located in the southeastern United States. The state borders South Carolina and Georgia to the south, Tennessee to the west and Virginia to the north. North Carolina contains 100 counties. Its capital is Raleigh, and its largest city is Charlotte...

, and he made experimental transmissions across water to a station located about 5 miles (8 km) west of Cape Hatteras
Cape Hatteras
Cape Hatteras is a cape on the coast of North Carolina. It is the point that protrudes the farthest to the southeast along the northeast-to-southwest line of the Atlantic coast of North America...

, the distance between the two stations being almost exactly 50 miles (80.5 km). A dynamo of 1 kW output at 10 kilohertz was built in 1902. The credit for the development of this machine is due to Charles Proteus Steinmetz
Charles Proteus Steinmetz
Charles Proteus Steinmetz was a German-American mathematician and electrical engineer. He fostered the development of alternating current that made possible the expansion of the electric power industry in the United States, formulating mathematical theories for engineers...

, Caryl D. Haskins, Ernst Alexanderson
Ernst Alexanderson
Ernst Frederick Werner Alexanderson was a Swedish-American electrical engineer, who was a pioneer in radio and television development.-Background:...

, John T. H. Dempster, Henry Geisenhoner, Adam Stein, Jr., and F. P. Mansbendel.

In a paper written by Fessenden in 1902, it was asserted that important advances had been made, one of which was overcoming largely the loss of energy experienced in other systems. He also declared that syntony was not safely selecting,
Within the history of radio
History of radio
The early history of radio is the history of technology that produced radio instruments that use radio waves. Within the timeline of radio, many people contributed theory and inventions in what became radio. Radio development began as "wireless telegraphy"...

, several people were involved in the invention of radio and there were many key inventions in what became the modern systems of wireless
Wireless
Wireless telecommunications is the transfer of information between two or more points that are not physically connected. Distances can be short, such as a few meters for television remote control, or as far as thousands or even millions of kilometers for deep-space radio communications...

. Radio
Radio
Radio is the transmission of signals through free space by modulation of electromagnetic waves with frequencies below those of visible light. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space...

 development began as "wireless telegraphy
Wireless telegraphy
Wireless telegraphy is a historical term used today to apply to early radio telegraph communications techniques and practices, particularly those used during the first three decades of radio before the term radio came into use....

". During the early development of wireless technology, and continuing long after its widespread adoption, disputes persisted as to who could claim credit for the invention of radio. The matter was important for economic, political and nationalistic reasons.

Physics of wireless signalling


Various scientists proposed that electricity and magnetism
Electromagnetism
Electromagnetism is one of the four fundamental interactions in nature. The other three are the strong interaction, the weak interaction and gravitation...

 were linked. In 1802 Gian Domenico Romagnosi
Gian Domenico Romagnosi
Gian Domenico Romagnosi was an Italian philosopher, economist and jurist.-Biography:Gian Domenico Romagnosi was born in Salsomaggiore Terme....

 suggested the relationship between electric current and magnetism but his reports went unnoticed. In 1820 Hans Christian Ørsted
Hans Christian Ørsted
Hans Christian Ørsted was a Danish physicist and chemist who discovered that electric currents create magnetic fields, an important aspect of electromagnetism...

 performed a simple and today widely known experiment on man-made electric current and magnetism. He demonstrated that a wire carrying a current could deflect a magnetized compass
Compass
A compass is a navigational instrument that shows directions in a frame of reference that is stationary relative to the surface of the earth. The frame of reference defines the four cardinal directions – north, south, east, and west. Intermediate directions are also defined...

 needle. Ørsted's work influenced André-Marie Ampère
André-Marie Ampère
André-Marie Ampère was a French physicist and mathematician who is generally regarded as one of the main discoverers of electromagnetism. The SI unit of measurement of electric current, the ampere, is named after him....

 to produce a theory of electromagnetism.

Several different electrical, magnetic or electromagnetic physical phenomena can be used to transmit signals over a distance without intervening wires. The various methods for wireless signal transmissions include:
  • Electrical conduction through the ground, or through water.
  • Magnetic induction
    Electromagnetic induction
    Electromagnetic induction is the production of an electric current across a conductor moving through a magnetic field. It underlies the operation of generators, transformers, induction motors, electric motors, synchronous motors, and solenoids....

  • Capacitive coupling
    Capacitive coupling
    In electronics, capacitive coupling is the transfer of energy within an electrical network by means of the capacitance between circuit nodes. This coupling can have an intentional or accidental effect...

  • Electromagnetic waves
    Electromagnetic radiation
    Electromagnetic radiation is a form of energy that exhibits wave-like behavior as it travels through space...


All these physical phenomena, as well as various other ideas such as conduction through air, were tested for the purpose of communication. Early researchers may not have understood or disclosed which physical effects were responsible for transmitting signals. Early experiments used the existing theories of the movement of charged particles through an electrical conductor. There was no theory of electromagnetic wave propagation to guide experiments before Maxwell's treatise and its verification by Hertz and others.

Capacitive and inductive coupling systems today are used only for short-range special purpose systems. The physical phenomenon used today for long-distance wireless communications involves the use of modulated electromagnetic waves, which is radio.

Radio antennas radiate electromagnetic waves that can reach the receiver
Radio propagation
Radio propagation is the behavior of radio waves when they are transmitted, or propagated from one point on the Earth to another, or into various parts of the atmosphere...

 either by ground wave propagation, by refraction from the ionosphere, known as sky wave propagation, and occasionally by refraction in lower layers of the atmosphere (tropospheric ducting). The ground wave component is the portion of the radiated electromagnetic wave that propagates close to the Earth's surface. It has both direct-wave and ground-reflected components. The direct-wave is limited only by the distance from the transmitter to the horizon plus a distance added by diffraction around the curvature of the earth. The ground-reflected portion of the radiated wave reaches the receiving antenna after being reflected from the Earth's surface. A portion of the ground wave energy radiated by the antenna may also be guided by the Earth's surface as a ground-hugging surface wave
Surface wave
In physics, a surface wave is a mechanical wave that propagates along the interface between differing media, usually two fluids with different densities. A surface wave can also be an electromagnetic wave guided by a refractive index gradient...

.

Any change in the electrical conditions of a circuit, whether internal, such as a change of load, starting and switching operations, short circuits, or external, such as due to lightning, involves a readjustment of the stored electromagnetic and electrostatic energy of the circuit; that is, a so-called transient. Such transient is of the general character of a condenser discharge through an inductive circuit. The phenomenon of the condenser discharge through an inductive circuit therefore is of the greatest importance to the engineer, as the foremost cause of high-voltage and high-frequency troubles in electric circuits.

With the development of radio communication—whether wireless or wired—the condenser discharge through an inductive circuit has assumed a great additional importance since, with the exception of a few of the highest power transoceanic stations, which use power-driven high-frequency alternators, the source of power in the radio communication up to 1922 was the condenser discharge through the inductive circuit, whether as a damped wave or as an undamped wave. In undamped wave radio communication, the condenser discharge circuit is coupled with a source of electric power—a battery—in such a manner, that, without interfering with the character of the oscillation, sufficient energy is fed into the circuit to maintain the oscillation, similarly as in the clock, the pendulum is coupled with a source of mechanical power—weight or spring— so as to maintain its oscillation undamped. The usual method of producing a condenser discharge through an inductive circuit is gradually to charge a condenser from a source of electric power, until the condenser voltage has risen sufficiently high to jump a spark gap (the rotary gap, or quenched gap of the damped wave wireless for instance) and thereby discharge through the inductive circuit.

Theory of electromagnetism





Several scientists speculated that light might be connected with electricity or magnetism. Around 1830 Francesco Zantedeschi
Francesco Zantedeschi
Francesco Zantedeschi was an Italian priest and physicist.-Biography:A native of Dolcè, near Verona, Zantedeschi was for some time professor of physics and philosophy in the Liceo of Venice. Later he accepted the chair of physics in the University of Padua, which he held until 1853 being then...

 suggested a connection between light, electricity, and magnetism. In 1832 Joseph Henry
Joseph Henry
Joseph Henry was an American scientist who served as the first Secretary of the Smithsonian Institution, as well as a founding member of the National Institute for the Promotion of Science, a precursor of the Smithsonian Institution. During his lifetime, he was highly regarded...

 performed experiments detecting electromagnetic effects over a distance of 200 feet (61 m) and postulated the existence of electromagnetic waves.

In 1831, Michael Faraday
Michael Faraday
Michael Faraday, FRS was an English chemist and physicist who contributed to the fields of electromagnetism and electrochemistry....

 began a series of experiments in which he discovered electromagnetic induction
Electromagnetic induction
Electromagnetic induction is the production of an electric current across a conductor moving through a magnetic field. It underlies the operation of generators, transformers, induction motors, electric motors, synchronous motors, and solenoids....

. The relation was mathematically modelled by Faraday's law
Faraday's law of induction
Faraday's law of induction dates from the 1830s, and is a basic law of electromagnetism relating to the operating principles of transformers, inductors, and many types of electrical motors and generators...

, which subsequently became one of the four Maxwell equations
Maxwell's equations
Maxwell's equations are a set of partial differential equations that, together with the Lorentz force law, form the foundation of classical electrodynamics, classical optics, and electric circuits. These fields in turn underlie modern electrical and communications technologies.Maxwell's equations...

. Faraday proposed that electromagnetic forces extended into the empty space around the conductor, but did not complete his work involving that proposal. In 1846 Michael Faraday speculated that light was a wave disturbance in a force field".

Between 1861 and 1865, based on the earlier experimental work of Faraday and other scientists, James Clerk Maxwell
James Clerk Maxwell
James Clerk Maxwell of Glenlair was a Scottish physicist and mathematician. His most prominent achievement was formulating classical electromagnetic theory. This united all previously unrelated observations, experiments and equations of electricity, magnetism and optics into a consistent theory...

 developed his theory of electromagnetism, which predicted the existence of electromagnetic waves. In 1873 Maxwell described the theoretical basis of the propagation of electromagnetic waves in his paper to the Royal Society
Royal Society
The Royal Society of London for Improving Natural Knowledge, known simply as the Royal Society, is a learned society for science, and is possibly the oldest such society in existence. Founded in November 1660, it was granted a Royal Charter by King Charles II as the "Royal Society of London"...

, "A Dynamical Theory of the Electromagnetic Field
A Dynamical Theory of the Electromagnetic Field
"A Dynamical Theory of the Electromagnetic Field" is the third of James Clerk Maxwell's papers regarding electromagnetism, published in 1865. It is the paper in which the original set of four Maxwell's equations first appeared...

."

Based on the experimental work of Faraday and other physicists, James Clerk Maxwell
James Clerk Maxwell
James Clerk Maxwell of Glenlair was a Scottish physicist and mathematician. His most prominent achievement was formulating classical electromagnetic theory. This united all previously unrelated observations, experiments and equations of electricity, magnetism and optics into a consistent theory...

 in 1864 developed the theory of electromagnetism
Electromagnetism
Electromagnetism is one of the four fundamental interactions in nature. The other three are the strong interaction, the weak interaction and gravitation...

 that predicted the existence of electromagnetic waves, which include radio waves. This theory united all previously unrelated observations, experiments and equations of electricity, magnetism, and optics into a consistent theory. His set of equations—Maxwell's equations
Maxwell's equations
Maxwell's equations are a set of partial differential equations that, together with the Lorentz force law, form the foundation of classical electrodynamics, classical optics, and electric circuits. These fields in turn underlie modern electrical and communications technologies.Maxwell's equations...

—demonstrated that electricity, magnetism, and light are all manifestations of the same phenomenon, the electromagnetic field
Electromagnetic field
An electromagnetic field is a physical field produced by moving electrically charged objects. It affects the behavior of charged objects in the vicinity of the field. The electromagnetic field extends indefinitely throughout space and describes the electromagnetic interaction...

. Subsequently, all other classic laws or equations of these disciplines were special cases of Maxwell's equations. Maxwell's work in electromagnetism has been called the "second great unification in physics".

Although Maxwell did not transmit or receive radio waves his equations still remain the basis of all radio design. Berend Wilhelm Feddersen
Berend Wilhelm Feddersen
Berend Wilhelm Feddersen was a German physicist.-Biography:Feddersen lived from 1858 as a private scholar in Leipzig. In 1859 he succeeded in experiments with the Leyden jar to prove that every single electric spark discharge composed of oscillations...

 (German physicist) in 1859, as a private scholar in Leipzig
Leipzig
Leipzig Leipzig has always been a trade city, situated during the time of the Holy Roman Empire at the intersection of the Via Regia and Via Imperii, two important trade routes. At one time, Leipzig was one of the major European centres of learning and culture in fields such as music and publishing...

, succeeded in experiments with the Leyden jar to prove that electric spark
Electric spark
An electric spark is a type of electrostatic discharge that occurs when an electric field creates an ionized electrically conductive channel in air producing a brief emission of light and sound. A spark is formed when the electric field strength exceeds the dielectric field strength of air...

s were composed of discharge (damped) oscillations. He realized that they arise from a coil, capacitor and resistor existing electrical circuit oscillations.

Formative "wireless" methods


In April 1872 William Henry Ward
William Henry Ward
William Henry Ward on 30 April 1872 was granted a USA patent for "Improvement for collecting electricity for telegraphing" . He theorized that an "electrical layer in the atmosphere" could carry signals like a telegraph wire, and thus is sometimes listed among supposed inventors of radio.-External...

 received for radio development. However, this patent did not refer to any known scientific theory of electromagnetism and could never have received and transmitted radio waves.

A few months after Ward received his patent, Mahlon Loomis
Mahlon Loomis
Mahlon Loomis was an early wireless telegraph experimenter.-Early history:...

 of West Virginia
West Virginia
West Virginia is a state in the Appalachian and Southeastern regions of the United States, bordered by Virginia to the southeast, Kentucky to the southwest, Ohio to the northwest, Pennsylvania to the northeast and Maryland to the east...

 received for a "wireless telegraph" in July 1872. This claimed to utilize atmospheric electricity
Atmospheric electricity
Atmospheric electricity is the regular diurnal variations of the Earth's atmospheric electromagnetic network . The Earth's surface, the ionosphere, and the atmosphere is known as the global atmospheric electrical circuit...

 to eliminate the overhead wire used by the existing telegraph systems. It did not contain diagrams or specific methods and it did not refer to or incorporate any known scientific theory. It is substantially similar to William Henry Ward
William Henry Ward
William Henry Ward on 30 April 1872 was granted a USA patent for "Improvement for collecting electricity for telegraphing" . He theorized that an "electrical layer in the atmosphere" could carry signals like a telegraph wire, and thus is sometimes listed among supposed inventors of radio.-External...

's patent and could not have transmitted and received radio waves.

Towards the end of 1875, while experimenting with the telegraph, Thomas Edison
Thomas Edison
Thomas Alva Edison was an American inventor and businessman. He developed many devices that greatly influenced life around the world, including the phonograph, the motion picture camera, and a long-lasting, practical electric light bulb. In addition, he created the world’s first industrial...

 noted a phenomenon that he termed "etheric force
Etheric force
Etheric force, a term coined by Thomas Edison to describe a phenomenon that was later to be understood as high frequency electromagnetic waves, effectively, radio...

", announcing it to the press on November 28. He abandoned this research when Elihu Thomson
Elihu Thomson
Elihu Thomson was an American engineer and inventor who was instrumental in the founding of major electrical companies in the United States, the United Kingdom and France.-Early life:...

, among others, ridiculed the idea. The idea was not based on the electromagnetic waves described by Maxwell. In 1885, Edison took out on a system of electrical wireless communication between ships (which later he sold to the Marconi Company
Marconi Company
The Marconi Company Ltd. was founded by Guglielmo Marconi in 1897 as The Wireless Telegraph & Signal Company...

). The patent, however, was based on the mutual-inductively coupled or magnetically coupled communication.

Claims have been made that Murray, Kentucky
Murray, Kentucky
Murray is a city in Calloway County, Kentucky, United States. The population was 17,741 at the 2010 census and has a micropolitan area population of 37,191. It is the 22nd largest city in Kentucky...

 farmer Nathan Stubblefield
Nathan Stubblefield
Nathan B. Stubblefield was an American inventor and Kentucky melon farmer. It has been claimed that Stubblefield invented the radio before either Nikola Tesla or Guglielmo Marconi, but his devices seem to have worked by audio frequency induction or, later, audio frequency earth conduction rather...

 developed radio between 1885 and 1892, before either Tesla or Marconi, but his devices seemed to have worked by induction
Electromagnetic induction
Electromagnetic induction is the production of an electric current across a conductor moving through a magnetic field. It underlies the operation of generators, transformers, induction motors, electric motors, synchronous motors, and solenoids....

 transmission rather than radio transmission
Radio propagation
Radio propagation is the behavior of radio waves when they are transmitted, or propagated from one point on the Earth to another, or into various parts of the atmosphere...

.

In 1878, David E. Hughes
David E. Hughes
David Edward Hughes , was a British scientist and musician. Hughes was co-inventor of the microphone, a harpist and a professor of music.-Biography:...

 noticed that sparks could be heard in a telephone receiver when experimenting with his carbon microphone. He developed this carbon-based detector further and eventually could detect signals over a few hundred yards. He demonstrated his discovery to the Royal Society in 1880, but was told it was merely induction
Electromagnetic induction
Electromagnetic induction is the production of an electric current across a conductor moving through a magnetic field. It underlies the operation of generators, transformers, induction motors, electric motors, synchronous motors, and solenoids....

, and therefore abandoned further research, although there have been later claims that he did, in fact, transmit and receive electromagnetic waves. While Professor Hughes was continuing his investigations in this direction, Hertz's papers were published, and then he thought it too late to bring forward these earlier experiments.

Early radio development




The key invention for the beginning of "wireless transmission of data using the entire frequency spectrum", known as the spark-gap transmitter
Spark-gap transmitter
A spark-gap transmitter is a device for generating radio frequency electromagnetic waves using a spark gap.These devices served as the transmitters for most wireless telegraphy systems for the first three decades of radio and the first demonstrations of practical radio were carried out using them...

, has been attributed to various men. Marconi equipped ships with lifesaving wireless communications and established the first transatlantic radio service. Tesla developed means to reliably produce radio frequency electrical currents, publicly demonstrated the principles of radio, and transmitted long distance signals.

In the late 19th century it was clear to various scientists and experimenters that wireless communication was possible. Various theoretical and experimental innovations led to the development of radio and the communication system we know today. Some early work was done by local effects
Near and far field
The near field and far field and the transition zone are regions of the electromagnetic radiation field that emanates from a transmitting antenna, or as a result of radiation scattering off an object...

 and experiment
Experiment
An experiment is a methodical procedure carried out with the goal of verifying, falsifying, or establishing the validity of a hypothesis. Experiments vary greatly in their goal and scale, but always rely on repeatable procedure and logical analysis of the results...

s of electromagnetic induction
Electromagnetic induction
Electromagnetic induction is the production of an electric current across a conductor moving through a magnetic field. It underlies the operation of generators, transformers, induction motors, electric motors, synchronous motors, and solenoids....

. Many understood that there was nothing similar to the "ethereal
Aether (classical element)
According to ancient and medieval science aether , also spelled æther or ether, is the material that fills the region of the universe above the terrestrial sphere.-Mythological origins:...

 telegraphy"
and telegraphy by induction
Radio-frequency induction
Radio-frequency induction or RF induction is the use of a radio frequency magnetic field to transfer energy by means of electromagnetic induction in the near field...

, the phenomena being wholly distinct. Wireless telegraphy was beginning to take hold and the practice of transmitting messages without wires was being developed. Many people worked on developing the devices and improvements.

Early radio's origin and development of old, or damped wave-coherer, methods began with Joseph Henry. He was the first (1838–42) to produce high frequency electrical oscillations, and to point out and experimentally demonstrate that the discharge of a condenser is under certain conditions oscillatory, or, as he puts it, consists "of a principal discharge in one direction and then several reflex actions backward and forward, each more feeble than the preceding until equilibrium is attained". This view was also later adopted by Helmholz, but the mathematical demonstration of this fact was first given by Lord Kelvin in his paper on "Transient Electric Currents".

In 1870 the German physicist Wilhelm von Bezold
Wilhelm von Bezold
Johann Friedrich Wilhelm von Bezold was a German physicist and meteorologist born in Munich, Kingdom of Bavaria....

 discovered and experimentally demonstrated the fact that the advancing and reflected oscillations produced in conductors by a condenser discharge gave rise to interference phenomena. Professors Elihu Thomson
Elihu Thomson
Elihu Thomson was an American engineer and inventor who was instrumental in the founding of major electrical companies in the United States, the United Kingdom and France.-Early life:...

 and E. J. Houston in 1876 made a number of experiments and observations on high frequency oscillatory discharges. In 1883 G. F. Fitzgerald suggested at a British Association meeting that electromagnetic waves could be generated by the discharge of a condenser, but the suggestion was not followed up, possibly because no means was known for detecting the waves.

Hertz discovered a method of detecting such waves by means of a minute spark-gap and, before March 30, 1888, had concluded his remarkable series of researches in which for the first time electromagnetic waves were actually produced by a spark-gap and radiating conductor and received and detected at a distance by a tuned receiving circuit. Hertz changed the frequency of his radiated waves by altering the inductance or capacity of his radiating conductor or antenna, and reflected and focused the electromagnetic waves, thus demonstrating the correctness of Maxwell's electromagnetic theory of light. After Hertz, Sir William Crookes
William Crookes
Sir William Crookes, OM, FRS was a British chemist and physicist who attended the Royal College of Chemistry, London, and worked on spectroscopy...

 discussed the matter of wireless in some detail. Professor Amos Emerson Dolbear
Amos Dolbear
Amos Emerson Dolbear was an American physicist and inventor. His patents interfered with Guglielmo Marconi's planned activities in the U.S. Dolbear researched electrical spark conversion into sound waves and electrical impulses. He was a professor at University of Kentucky in Lexington from 1868...

 also suggested the same thing.

Hertz


Between 1886 and 1888, Heinrich Rudolf Hertz
Heinrich Rudolf Hertz
Heinrich Rudolf Hertz was a German physicist who clarified and expanded the electromagnetic theory of light that had been put forth by Maxwell...

 studied Maxwell's theory and validated it through experiment. Concerning wireless telegraphy, he demonstrated the transmission and reception of the electromagnetic waves predicted by Maxwell and intentionally transmitted and received radio. Hertz changed the frequency of his radiated waves by altering the inductance or capacity of his radiating conductor or antenna, and reflected and focused the electromagnetic waves, thus demonstrating the correctness of Maxwell's electromagnetic theory of light. Famously, he saw no practical use for his discovery.

In his UHF
Ultra high frequency
Ultra-High Frequency designates the ITU Radio frequency range of electromagnetic waves between 300 MHz and 3 GHz , also known as the decimetre band or decimetre wave as the wavelengths range from one to ten decimetres...

 experiments, he transmitted and received radio waves over short distances and showed that the properties of radio waves were consistent with Maxwell’s electromagnetic theory. He demonstrated that radio radiation (now called electromagnetic radiation) had all the properties of waves, and discovered that the electromagnetic equations could be reformulated into a partial differential equation
Partial differential equation
In mathematics, partial differential equations are a type of differential equation, i.e., a relation involving an unknown function of several independent variables and their partial derivatives with respect to those variables...

 called the wave equation
Wave equation
The wave equation is an important second-order linear partial differential equation for the description of waves – as they occur in physics – such as sound waves, light waves and water waves. It arises in fields like acoustics, electromagnetics, and fluid dynamics...

.





Hertz’s setup for a source and detector of radio waves (then called Hertzian waves in his honor) was the first intentional and unequivocal transmission and reception of radio waves
Radio waves
Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. Radio waves have frequencies from 300 GHz to as low as 3 kHz, and corresponding wavelengths from 1 millimeter to 100 kilometers. Like all other electromagnetic waves,...

 through free space. The first of the papers published ("On Very Rapid Electric Oscillations") gives, generally in the actual order of time, the course of the investigation as far as it was carried out up to the end of the year 1886 and the beginning of 1887.

Hertz, though, did not devise a system for actual general use nor describe the application of the technology and seemed uninterested in the practical importance of his experiments. Asked about the ramifications of his discoveries, Hertz replied, "Nothing, I guess." Hertz also stated, "I do not think that the wireless waves I have discovered will have any practical application." Hertz died in 1894, and the art of radio was left to others to implement into a practical form.

Branly


In 1890, Édouard Branly
Edouard Branly
Édouard Eugène Désiré Branly was a French inventor, physicist and professor at the Institut Catholique de Paris. He is primarily known for his early involvement in wireless telegraphy and his invention of the Branly coherer around 1890.-Biography:The coherer was the first widely used detector for...

 demonstrated what he later called the "radio-conductor," which Lodge in 1893 named the coherer
Coherer
The coherer was a primitive form of radio signal detector used in the first radio receivers during the wireless telegraphy era at the beginning of the twentieth century. Invented around 1890 by French scientist Édouard Branly, it consisted of a tube or capsule containing two electrodes spaced a...

, the first sensitive device for detecting radio waves. Shortly after the experiments of Hertz, Dr. Branly discovered that loose metal filings, which in a normal state have a high electrical resistance, lose this resistance in the presence of electric oscillations and become practically conductors of electricity. This Branly showed by placing metal filings in a glass box or tube, and making them part of an ordinary electric circuit. According to the common explanation, when electric waves are set up in the neighborhood of this circuit, electromotive forces are generated in it which appear to bring the filings more closely together, that is, to cohere, and thus their electrical resistance decreases, from which cause this piece of apparatus was termed by Sir Oliver Lodge a coherer. Hence the receiving instrument, which may be a telegraph relay, that normally would not indicate any sign of current from the small battery, can be operated when electric oscillations are set up. Prof. Branly further found that when the filings had once cohered they retained their low resistance until shaken apart, for instance, by tapping on the tube. The coherer, however, was not sensitive enough to be used reliably as radio developed.

Tesla


In 1891 Nikola Tesla
Nikola Tesla
Nikola Tesla was a Serbian-American inventor, mechanical engineer, and electrical engineer...

 began his research into radio. Around July 1891 he developed various alternator apparatus
Alternator
An alternator is an electromechanical device that converts mechanical energy to electrical energy in the form of alternating current.Most alternators use a rotating magnetic field but linear alternators are occasionally used...

 that produced 15,000 cycles per second
Very low frequency
225px|thumb|right|A VLF receiving antenna at [[Palmer Station]], Antarctica, operated by Stanford UniversityVery low frequency or VLF refers to radio frequencies in the range of 3 kHz to 30 kHz. Since there is not much bandwidth in this band of the radio spectrum, only the very simplest signals...

. In 1892 he delivered a lecture called "Experiments with Alternate Currents of High Potential and High Frequency" before the Institution of Electrical Engineers
Institution of Electrical Engineers
The Institution of Electrical Engineers was a British professional organisation of electronics, electrical, manufacturing, and Information Technology professionals, especially electrical engineers. The I.E.E...

 of London, in which he suggested that messages could be transmitted without wires. He repeated this presentation at the Royal Institution
Royal Institution
The Royal Institution of Great Britain is an organization devoted to scientific education and research, based in London.-Overview:...

 and at the Société Française de Physique in Paris. Tesla realized he gained, by the use of very high frequencies, many advantages in his experiments, such as the possibilities of working with one lead and of doing away with the leading-in wire. In transmitting impulses through conductors, he dealt with high pressure and high flow, in the ordinary interpretation of these terms. Towards the end of the lecture, he proposed that sending over the wire current vibrations of very high frequencies at enormous distance without affecting greatly the character of the vibrations and that telephony could be rendered practicable across the Atlantic. He also proposed transmission through the Earth. Tesla captured the attention of the whole scientific world by his fascinating experiments on high frequency electric currents. He stimulated the scientific imagination of others as well as displayed his own, and created a widespread interest in his brilliant demonstrations. Accordingly there are seven elements in the complete oscillation-producing appliance, which are as follows:
  • The induction coil transformer or source of electromotive force
    Electromotive force
    In physics, electromotive force, emf , or electromotance refers to voltage generated by a battery or by the magnetic force according to Faraday's Law, which states that a time varying magnetic field will induce an electric current.It is important to note that the electromotive "force" is not a...

    .
  • The condenser
    Capacitor
    A capacitor is a passive two-terminal electrical component used to store energy in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors separated by a dielectric ; for example, one common construction consists of metal foils separated...

    .
  • The discharger
    Discharger
    A discharger in electronics is a device or circuit that releases stored energy or electric charge from a battery, capacitor or other source.Discharger types include:* metal probe with insulated handle & ground wire, and sometimes resistor...

     or spark ball
    Spark gap
    A spark gap consists of an arrangement of two conducting electrodes separated by a gap usually filled with a gas such as air, designed to allow an electric spark to pass between the conductors. When the voltage difference between the conductors exceeds the gap's breakdown voltage, a spark forms,...

    s.
  • The arc quenching inductances.
  • The oscillation transformer.
  • The adjustable inductance for varying the period.
  • The controller or key
    Telegraph key
    Telegraph key is a general term for any switching device used primarily to send Morse code. Similar keys are used for all forms of manual telegraphy, such as in electrical telegraph and radio telegraphy.- Types of keys :...

     in the primary circuit of the coil or transformer.

These several elements have each to be considered separately with reference to their best practical forms for various purposes. When the key is closed, and the apparatus in operation, there are trains of intermittent electrical oscillations set up in the circuit, and if the terminals of the secondary circuit of the oscillation transformer are near together, there is high potential high frequency oscillatory sparks passing between them. The above-described apparatus in a typical form is generally called a Tesla apparatus for the production of high frequency electric currents.


"On Light and Other High Frequency Phenomena"


In 1893, at St. Louis, Missouri
St. Louis, Missouri
St. Louis is an independent city on the eastern border of Missouri, United States. With a population of 319,294, it was the 58th-largest U.S. city at the 2010 U.S. Census. The Greater St...

, Tesla gave a public demonstration, "On Light and Other High Frequency Phenomena", of wireless communication. Addressing the Franklin Institute
Franklin Institute
The Franklin Institute is a museum in Philadelphia, Pennsylvania, and one of the oldest centers of science education and development in the United States, dating to 1824. The Institute also houses the Benjamin Franklin National Memorial.-History:On February 5, 1824, Samuel Vaughn Merrick and...

in Philadelphia, he described in detail the principles of early radio communication. The lecture apparatus that Tesla used contained all the elements that were incorporated into radio systems before the development of the "oscillation valve", the early vacuum tube
Vacuum tube
In electronics, a vacuum tube, electron tube , or thermionic valve , reduced to simply "tube" or "valve" in everyday parlance, is a device that relies on the flow of electric current through a vacuum...

. The lecture delivered before the Franklin Institute, at Philadelphia, occurred on February 24, 1893. The variety of Tesla's radio frequency systems were again demonstrated during when he presented to meetings of the National Electric Light Association
National Electric Light Association
The National Electric Light Association was a national United States trade association including the operators of central power generation stations and interested individuals. Founded in 1885 by G. S. Bowen Terry and Charles A. Brown, it represented the interests of various private companies...

, at St. Louis, on March I, 1893. Afterward, the principle of radio communication (sending signals through space to receivers) was publicized widely from Tesla's experiments and demonstrations. On August 25, 1893, Tesla delivered the lecture "Mechanical and Electrical Oscillators", before the International Electrical Congress, in the hall adjoining the Agricultural Building, at the World's Fair, Chicago
World's Columbian Exposition
The World's Columbian Exposition was a World's Fair held in Chicago in 1893 to celebrate the 400th anniversary of Christopher Columbus's arrival in the New World in 1492. Chicago bested New York City; Washington, D.C.; and St...

.

The high-frequency phenomena which Tesla first developed and displayed had scientific rather than practical interest; but Tesla called attention to the fact that by taking the Tesla oscillator, grounding one side of it and connecting the other to an insulated body of large surface, it should be possible to transmit electric oscillations to a great distance, and to communicate intelligence in this way to other oscillators in sympathetic resonance therewith. This was going far toward the invention of radio-telegraphy as known in the early 20th century, as stated by the Electrical World in 1917.

Transmission and radiation of radio frequency energy was a feature exhibited in the experiments by Tesla which he proposed might be used for the telecommunication
Telecommunication
Telecommunication is the transmission of information over significant distances to communicate. In earlier times, telecommunications involved the use of visual signals, such as beacons, smoke signals, semaphore telegraphs, signal flags, and optical heliographs, or audio messages via coded...

 of information
Information
Information in its most restricted technical sense is a message or collection of messages that consists of an ordered sequence of symbols, or it is the meaning that can be interpreted from such a message or collection of messages. Information can be recorded or transmitted. It can be recorded as...

. The Tesla method
Wireless energy transfer
Wireless energy transfer or wireless power is the transmission of electrical energy from a power source to an electrical load without artificial interconnecting conductors. Wireless transmission is useful in cases where interconnecting wires are inconvenient, hazardous, or impossible...

 was mentioned in New York in 1897. In Buffalo, New York, he referred to devised means for transmission of electromotive force
Electromotive force
In physics, electromotive force, emf , or electromotance refers to voltage generated by a battery or by the magnetic force according to Faraday's Law, which states that a time varying magnetic field will induce an electric current.It is important to note that the electromotive "force" is not a...

s, much higher than practical with ordinary apparatus, and the transmission of power from station to station without the employment of any connecting wire. Tesla later, on April 6, 1897, explained his methods of the transformation of electrical energy by oscillatory condenser discharges in his lecture "The stream of Lenard and Roentgen and novel apparatus for their production". He demonstrated his subject by a fine array of improved apparatus, in which a few feet of wire were made as efficient as miles under old systems.


In 1894, T. C. Martin
Thomas Commerford Martin
Thomas Commerford Martin was an American electrical engineer and editor, born in London, England. His father worked with Lord Kelvin and other pioneers of submarine telegraph cables, and Martin spent much time on the cable-laying ship SS Great Eastern. Educated as a theological student, Martin...

 published "The Inventions, Researches and Writings of Nikola Tesla", detailing the work of Tesla in the previous years. Various scientists, inventors, and experimenters began to investigate wireless methods. Telsa's work contained coupled oscillation circuits having capacity and inductance in series. In 1897, Tesla applied for two key United States radio patents, , first radio system patent, and (later subdivided into) , for protection of his interests of the radio arts. Tesla also developed sensitive electromagnetic receivers, that were unlike the less responsive coherers later used by other early experimenters.

Shortly thereafter, he began to develop wireless remote control
Remote control
A remote control is a component of an electronics device, most commonly a television set, used for operating the television device wirelessly from a short line-of-sight distance.The remote control is usually contracted to remote...

 devices. In 1898, he demonstrated a radio controlled boat in Madison Square Garden
Madison Square Garden (1890)
Madison Square Garden was an indoor arena in New York City, the second by that name, and the second to be located at 26th Street and Madison Avenue in Manhattan...

 that allowed secure communication
Secure communication
When two entities are communicating and do not want a third party to listen in, they need to communicate in a way not susceptible to eavesdropping or interception. This is known as communicating in a secure manner or secure communication...

 between transmitter and receiver. Between 1895 and 1897, Tesla received wireless signals transmitted via short distances in his lectures. Between 1897 and the first decade of the 1900s, he transmitted over medium ranges. Tesla had predicted that not only would intelligible signals be transmitted over long distances without wires, but electric power as well. He later published articles, such as
"The True Wireless", and "The Transmission of Electric Energy Without Wires", concerning the World Wireless System research.

de Moura


Roberto Landell de Moura, a Brazilian priest and scientist, went to Rome in 1878 and studied at the South American College
South American College in Rome
The South American College in Rome is one of the Roman Colleges of the Roman Catholic Church, for students from Central and South America.-History:...

 and Pontifical Gregorian University
Pontifical Gregorian University
The Pontifical Gregorian University is a pontifical university located in Rome, Italy.Heir of the Roman College founded by Saint Ignatius of Loyola over 460 years ago, the Gregorian University was the first university founded by the Jesuits...

, where he studied physics and chemistry. He completed his clerical training in Rome, graduating in theology and was ordained priest in 1886. In Rome, he started studying physics and electricity. When he returned to Brazil, he conducted experiments in wireless in Campinas
Campinas
Campinas is a city and municipality located in the coastal interior of the state of São Paulo, Brazil. is the administrative center of the meso-region of the same name, with 3,783,597 inhabitants as of the 2010 Census, consisting of 49 cities....

 and São Paulo
São Paulo
São Paulo is the largest city in Brazil, the largest city in the southern hemisphere and South America, and the world's seventh largest city by population. The metropolis is anchor to the São Paulo metropolitan area, ranked as the second-most populous metropolitan area in the Americas and among...

 (1892–1893). The experiments of de Moura were performed in the presence of the English Vice Consul S. Paul, Percy Parmenter, Charles Lupton
Charles Lupton
Captain Charles Roger Lupton was a World War I flying ace credited with five aerial victories.-References:...

, and other persons of high social position. Upon observing the experiments, Rodriguez Botet, giving news of the trials, said he was not far from the moment of the consecration of Landell as an author of radio discoveries. The wireless telephony is reputed the most important discoveries of Landell. De Moura did later pursue and receive several patents on wireless technology. He would later obtain for a wireless telephone.

Lodge


One of the first investigators to notice and measure stationary waves on wires produced by direct coupling
Direct coupling
In electronics, direct coupling is a way of interconnecting two circuits such that, in addition to transferring the AC signal , the first stage also provides DC bias to the next...

 (resonance
Resonance
In physics, resonance is the tendency of a system to oscillate at a greater amplitude at some frequencies than at others. These are known as the system's resonant frequencies...

) with the coatings of a Leyden jar was Sir Oliver Lodge, entitled "Experiments On The Discharge Of Leyden Jars" (1891). On June, 1, 1894, Oliver Lodge at the Royal Institution lectures, delivered "The Work of Hertz and Some of His Successors". Two years after Tesla's high potential and high frequency lecture and five years after Hertz's signals, Lodge performed transmission on August 14, 1894. This was a year before Marconi's initial experiments. Lodge did this at a meeting of the British Association for the Advancement of Science
British Association for the Advancement of Science
frame|right|"The BA" logoThe British Association for the Advancement of Science or the British Science Association, formerly known as the BA, is a learned society with the object of promoting science, directing general attention to scientific matters, and facilitating interaction between...

 at Oxford University. Also in 1894, Lodge would state that Alexander Muirhead
Alexander Muirhead
Alexander Muirhead, FRS, born in East Saltoun, East Lothian, Scotland was an electrical engineer specialising in wireless telegraphy.-Biography:...

 clearly foresaw the telegraphic importance of the transmission of transverse Hertzian waves. A convenient method of establishing stationary electric waves on wires is one which generally attribute to Ernst Lecher
Ernst Lecher
Ernst Lecher was an Austrian physicist who, from 1909, was head of the First Institute of Physics in Vienna. He is remembered for developing an apparatus— "Lecher lines"—to measure the wavelength and frequency of electromagnetic waves...

, and call the Lecher arrangement
Lecher lines
In electronics, a Lecher line or Lecher wires is a pair of parallel wires or rods that were used to measure the wavelength of radio waves, mainly at UHF and microwave frequencies. They form a short length of balanced transmission line. When attached to a source of radio frequency power such as a...

. As a matter of fact, it originated with Lodge and Hertz, whilst Edouard Sarasin and Lucien de la Rive gave it an improved form.

On that day in August 1894, Lodge demonstrated the reception of Morse code
Morse code
Morse code is a method of transmitting textual information as a series of on-off tones, lights, or clicks that can be directly understood by a skilled listener or observer without special equipment...

 signalling via radio waves using a "coherer
Coherer
The coherer was a primitive form of radio signal detector used in the first radio receivers during the wireless telegraphy era at the beginning of the twentieth century. Invented around 1890 by French scientist Édouard Branly, it consisted of a tube or capsule containing two electrodes spaced a...

". He later improved Branly's coherer by adding a "trembler" which dislodged clumped filings, thus restoring the device's sensitivity. In August 1898 he got , "Electric Telegraphy", that made wireless signals using Ruhmkorff coils or Tesla coil
Tesla coil
A Tesla coil is a type of resonant transformer circuit invented by Nikola Tesla around 1891. It is used to produce high voltage, low current, high frequency alternating current electricity. Tesla coils produce higher current than the other source of high voltage discharges, electrostatic machines...

s for the transmitter and a Branly coherer for the detector. This patent was utilizing the concept of "syntonic" tuning. In 1912 Lodge sold the patent to Marconi.
Lodge 1894 lecture

Lodge's June 1, 1894 lecture before the Royal Institution. described among other things the following:
  1. Filings coherer
  2. Vacuum coherer
  3. Automatic coherer tapper
  4. Metallic focusing wave reflector
  5. Grounded conductor
  6. Coupled system
  7. Method of detection

In this lecture, Lodge stated that in his estimate the apparatus used would respond to signals at a distance of 0.5 mile (0.80467 km).

In 1894 Lodge showed that the Branly coherer could be employed to transmit telegraphic signals, and in order that the filings should not remain "cohered" after the cessation of the electric oscillations, he devised an electro-mechanical "tapper" on the principle of the ordinary "buzzer," or electric door-bell, the hammer of which was caused to tap the glass tube as long as the electric oscillations continued. The filings thus virtually take the place of a key in the ordinary telegraph circuit. In the normal state the key is open; in the presence of electrical oscillations the key is closed. Thus, by opening and closing the key for a longer or shorter period, signals corresponding to dots and dashes may be produced. In other words, by setting up electric oscillations for periods of time corresponding to dots and dashes, messages may be transmitted from the sending station, and if, at the receiving station, a recording instrument (controlled by the coherer), such as the ordinary Morse register, be provided, a record of the message in dots and dashes may be obtained. Dr. Lodge in fact used a tapper operated continuously by clockwork.

In 1894, with the help of the Branly filings tube, Lodge gave a couple of demonstrations, one in June at the Royal Institution
Royal Institution
The Royal Institution of Great Britain is an organization devoted to scientific education and research, based in London.-Overview:...

 at Oxford and one in August at Oxford, to the British Association, using Hertz oscillators for transmitting signals, using a Morse key in connection with the sending coil, and a Thomson marine galvanometer for receiving them—sending the signals from one room to another through walls, and so on. Lodge sent them also across the quadrangle
Quadrangle (architecture)
In architecture, a quadrangle is a space or courtyard, usually rectangular in plan, the sides of which are entirely or mainly occupied by parts of a large building. The word is probably most closely associated with college or university campus architecture, but quadrangles may be found in other...

 of Liverpool College, but he applied very small power and did not try for big distances. At that time Dr. Alexander Muirhead
Alexander Muirhead
Alexander Muirhead, FRS, born in East Saltoun, East Lothian, Scotland was an electrical engineer specialising in wireless telegraphy.-Biography:...

 was struck with its applicability to practical telegraphy, and when in 1896 Sir William Preece told the British Association meeting (as it happened in his laboratory) at Liverpool that an Italian gentleman (at that time unknown)
Guglielmo Marconi
Guglielmo Marconi was an Italian inventor, known as the father of long distance radio transmission and for his development of Marconi's law and a radio telegraph system. Marconi is often credited as the inventor of radio, and indeed he shared the 1909 Nobel Prize in Physics with Karl Ferdinand...

 was interesting the Post Office in a secret box, Lodge knew practically what the box must contain, and immediately afterwards (the same day) he showed to a few friends a Morse tape instrument, very roughly working on that plan. Mr. Marconi and Sir William Preece together interested the whole world in the subject; great power was applied to the sender, and the matter became of financial importance. However, the American Patent Office gave Lodge a telegraphic patent based on his work, as published in 1894, after proof that this book had reached America in or before 1895.

Bose


In November 1894, the Indian physicist, Jagadish Chandra Bose, demonstrated publicly the use of radio waves in Calcutta
Kolkata
Kolkata , formerly known as Calcutta, is the capital of the Indian state of West Bengal. Located on the east bank of the Hooghly River, it was the commercial capital of East India...

, but he was not interested in patenting his work. Bose ignited gunpowder and rang a bell at a distance using electromagnetic waves, proving that communication signals can be sent without using wires. He sent and received radio waves over distance but did not commercially exploit this achievement.

The 1895 public demonstration by Bose in Calcutta was before Marconi's wireless signalling experiment on Salisbury Plain
Salisbury Plain
Salisbury Plain is a chalk plateau in central southern England covering . It is part of the Southern England Chalk Formation and largely lies within the county of Wiltshire, with a little in Hampshire. The plain is famous for its rich archaeology, including Stonehenge, one of England's best known...

 in England in May 1897. Bose demonstrated the ability of the electric rays to travel from the lecture room, and through an intervening room and passage, to a third room 75 feet (22.9 m) distant from the radiator, thus passing through three solid walls on the way, as well as the body of the chairman (who happened to be the Lieutenant-Governor). The receiver at this distance still had energy enough to make a contact which set a bell ringing, discharged a pistol, and exploded a miniature mine. To get this result from his small radiator, Bose set up an apparatus which curiously anticipated the lofty 'antennae' of modern wireless telegraphy— a circular metal plate at the top of a pole, 20 feet (6.1 m) high, being put in connection with the radiator and a similar one with the receiving apparatus.

The form of 'Coherer' devised by Professor Bose, and described by him at the end of his paper 'On a new Electro Polariscope' allowed for the sensibility and range to appear to leave little to be desired at the time. In 1896, the Daily Chronicle
Daily Chronicle
The Daily Chronicle was a British newspaper that was published from 1872 to 1930 when it merged with the Daily News to become the News Chronicle.-History:...

 of England reported on his UHF experiments: "The inventor (J.C. Bose) has transmitted signals to a distance of nearly a mile and herein lies the first and obvious and exceedingly valuable application of this new theoretical marvel."

After Bose's Friday Evening Discourses at the Royal Institution
Royal Institution
The Royal Institution of Great Britain is an organization devoted to scientific education and research, based in London.-Overview:...

, The Electric Engineer expressed 'surprise that no secret was at any time made as to its construction, so that it has been open to all the world to adopt it for practical and possibly money-making purposes.'
Bose was sometimes, and not unnaturally, criticised as unpractical for making no profit from his inventions.

In 1899, Bose announced the development of an "iron-mercury-iron coherer
Coherer
The coherer was a primitive form of radio signal detector used in the first radio receivers during the wireless telegraphy era at the beginning of the twentieth century. Invented around 1890 by French scientist Édouard Branly, it consisted of a tube or capsule containing two electrodes spaced a...

 with telephone
Telephone
The telephone , colloquially referred to as a phone, is a telecommunications device that transmits and receives sounds, usually the human voice. Telephones are a point-to-point communication system whose most basic function is to allow two people separated by large distances to talk to each other...

 detector
" in a paper presented at the Royal Society
Royal Society
The Royal Society of London for Improving Natural Knowledge, known simply as the Royal Society, is a learned society for science, and is possibly the oldest such society in existence. Founded in November 1660, it was granted a Royal Charter by King Charles II as the "Royal Society of London"...

, London. Later he received , "Detector for electrical disturbances" (1904), for a specific electromagnetic receiver. Bose would continue research and made other contributuions to the development of radio.

Rutherford


The New Zealander Ernest Rutherford, 1st Baron Rutherford of Nelson contributed to the development of radio. In 1895 he was awarded an Exhibition of 1851 Science Research Scholarship to Cambridge. He arrived in England with a reputation as an innovator and inventor, and distinguished himself in several fields, initially by working out the electrical properties of solids and then using wireless waves as a method of signalling. Rutherford was encouraged in his work by Sir Robert Ball, who had been scientific adviser to the body maintaining lighthouse
Lighthouse
A lighthouse is a tower, building, or other type of structure designed to emit light from a system of lamps and lenses or, in older times, from a fire, and used as an aid to navigation for maritime pilots at sea or on inland waterways....

s on the Irish coast; he wished to solve the difficult problem of a ship's inability to detect a lighthouse in fog. Sensing fame and fortune, Rutherford increased the sensitivity of his apparatus until he could detect electromagnetic waves via his electromagnetic receiver over a distance of several hundred meters. The hysteresis magnetic detector invented by Rutherford, and described by him in 1897, was used to determine the characteristics of electromagnetic waves, the ends of the little solenoid of the detector being attached to the mercury cups of the slider. The development, though, of wireless technology was left for others, as Rutherford continued purely scientific research. J. J. Thomson
J. J. Thomson
Sir Joseph John "J. J." Thomson, OM, FRS was a British physicist and Nobel laureate. He is credited for the discovery of the electron and of isotopes, and the invention of the mass spectrometer...

 realized that Rutherford was a researcher of ability and invited him to join in a study of the electrical conduction of gases.

Braun


Ferdinand Braun's major contributions were the introduction of a closed tuned circuit in the generating part of the transmitter, and its separation from the radiating part (the antenna) by means of inductive coupling, and later on the usage of crystals for receiving purposes. Braun experimented at first at the University of Strassbourg. Braun had written extensively on wireless subjects and was well known through his many contributions to the Electrician and other scientific journals. In 1899, he would apply for the patents, Electro telegraphy by means of condensers and induction colls and Wireless electro transmission of signals over surfaces.

Pioneers working on wireless devices eventually came to a limit of distance they could cover. Connecting the antenna directly to the spark gap produced only a heavily damped pulse train. There were only a few cycles before oscillations ceased. Braun's circuit afforded a much longer sustained oscillation because the energy encountered less loss swinging between coil and Leyden Jars. Also, by means of inductive antenna coupling the radiator was matched to the generator.

In spring 1899 Braun, accompanied by his colleagues Cantor and Zenneck, went to Cuxhaven to continue their experiments at the North Sea. On February 6, 1899, he would apply for the United States Patent, . Not before long he bridged a distance of 42 km to the city of Mutzing. On 24 September 1900 radio telegraphy signals were exchanged regularly with the island of Heligoland over a distance of 62 km. Lightvessels in the river Elbe and a coast station at Cuxhaven commenced a regular radio telegraph service. On August 6, 1901, he would apply for .

By 1904, the closed circuit system of wireless telegraphy, connected with the name of Braun, was well known and generally adopted in principle. The results of Braun's experiments, published in the Electrician, possess interest, apart from the method employed. Braun showed how the problem could be satisfactorily and economically solved. The closed circuit oscillator has the advantage, as was known, of being able to draw upon the kinetic energy in the oscillator circuit, and thus, owing to the fact that such a circuit can be given a much greater capacity than can be obtained with a radiating aerial alone, much more energy can be stored up and radiated by its employment. The emission is also prolonged, both results tending towards the attainment of the much desired train of undamped waves. The energy available, though greater than with the open system, was still inconsiderable unless very high potentials, with the attendant drawbacks, were used. Braun avoided the use of extremely high potentials for charging the gap and also makes use of a less wasteful gap by sub-dividing it. The chief point in his new arrangement, however, is not the sub-division of the gap merely but their arrangement, by which they are charged in parallel, at low voltages, and discharge in series. The Nobel Prize
Nobel Prize
The Nobel Prizes are annual international awards bestowed by Scandinavian committees in recognition of cultural and scientific advances. The will of the Swedish chemist Alfred Nobel, the inventor of dynamite, established the prizes in 1895...

 awarded to Braun in 1909 depicts this design.

Later radio development




Popov


During the Chicago World's Columbian Exhibition and the Third International Electrical Congress, Alexander Stepanovich Popov of Kronstadt, Russia
Kronstadt
Kronstadt , also spelled Kronshtadt, Cronstadt |crown]]" and Stadt for "city"); is a municipal town in Kronshtadtsky District of the federal city of St. Petersburg, Russia, located on Kotlin Island, west of Saint Petersburg proper near the head of the Gulf of Finland. Population: It is also...

 was a representative of the Russian Torpedo School. Afterward, he worked on his wireless designs. Popov conducted experiments along the lines of Hertz's research. In 1894-95 he built his first radio receiver, an improved version of coherer
Coherer
The coherer was a primitive form of radio signal detector used in the first radio receivers during the wireless telegraphy era at the beginning of the twentieth century. Invented around 1890 by French scientist Édouard Branly, it consisted of a tube or capsule containing two electrodes spaced a...

-based design by Oliver Lodge. In 1895, he built a coherer
Coherer
The coherer was a primitive form of radio signal detector used in the first radio receivers during the wireless telegraphy era at the beginning of the twentieth century. Invented around 1890 by French scientist Édouard Branly, it consisted of a tube or capsule containing two electrodes spaced a...

. Popov constructed a filings coherer, one form of which was used in some surveying experiments by the Russian government. He used early in 1895, the coherer auto-tapping mechanism, and substituted for the galvanometer an ordinary telegraphic relay. He operated this apparatus at a distance by means of a large radiator. One terminal of his coherer was connected to a conductor fastened to a mast about 30 ft. high on the top of the Institute building and the other terminal of the coherer was grounded.

Popov presented his radio receiver to the Russian Physical and Chemical Society on May 7, 1895 — the day has been celebrated in the Russian Federation as "Radio Day
Radio Day
Radio Day , Communications Workers' Day or Radio and Television Day is a commemoration of the development of radio in Russia...

". On this day, Popov performed a public demonstration of transmission and reception of radio waves used for communication at the Russian Physical and Chemical Society, using his coherer. The paper on his findings was published the same year (December 15, 1895). Popov had recorded, at the end of 1895, that he was hoping for distant signaling with radio waves. He did not apply for a patent for this invention. Popov's early experiments were transmissions of only 600 yards (548.6 m). Popov was the first to develop a practical communication system based on the coherer, and is usually considered by the Russians to have been the inventor of radio.

In 1895-96 Popov and others utilized the coherer to show the existence of atmospheric electricity, using for the purpose a vertical wire attached to the coherer. On March 24, 1896, Popov demonstrated in public the transmission of radio waves, between different campus buildings, to the Saint Petersburg
Saint Petersburg
Saint Petersburg is a city and a federal subject of Russia located on the Neva River at the head of the Gulf of Finland on the Baltic Sea...

 Physical Society. (This was before the public demonstration of the Marconi system around September 1896.) Per other accounts, however, Popov achieved these results only in December 1897—that is, after publication of Marconi's patent. In 1898 his signal was received 6 miles (9.7 km) away, and in 1899 130 miles (209.2 km) away.

His receiver proved to be able to sense lightning strikes at distances of up to 30 km, thus functioning as a lightning detector
Lightning detector
A lightning detector is a device that detects lightning produced by thunderstorms. There are three primary types of detectors: ground-based systems using multiple antennas, mobile systems using a direction and a sense antenna in the same location , and space-based systems.The device was invented in...

. In late 1895, Popov built a version of the receiver that was capable of automatically recording lightning strikes on paper rolls. Popov's system was eventually extended to function as a wireless telegraph, with a Morse key attached to the transmitter. There's some dispute regarding the first public test of this design. It is frequently stated that Popov used his radio to send a Morse code message over a distance of 250 m in 26 March 1896 (three months before Marconi's patent was filed). However, contemporary confirmations of this transmission are lacking. It is more likely that said experiment took place in December 1897.

In 1900, Popov stated at the Congress of Russian Electrical Engineers that, "the emission and reception of signals by Marconi by means of electric oscillations was nothing new, as in America Nikola Tesla
Nikola Tesla
Nikola Tesla was a Serbian-American inventor, mechanical engineer, and electrical engineer...

 did the same experiments in 1893
." Also in 1900, a radio station was established under Popov's instructions on Hogland
Hogland
Gogland or Hogland is an island in the Gulf of Finland of the Baltic Sea, located some 180 km west of Saint Petersburg and 35 km away from the coast of Finland . The island is a part of the Leningrad Oblast, Russia. The area of Hogland Island is approximately...

 island (Suursaari) to provide two-way communication by wireless telegraphy between the Russian naval base and the crew of the battleship General-Admiral Apraksin. By February 5 messages were being received reliably. The wireless messages were relayed to Hogland Island by a station some 25 miles (40.2 km) away at Kymi (nowadays Kotka
Kotka
Kotka is a town and municipality of Finland. Its former name is Rochensalm.Kotka is located on the coast of the Gulf of Finland at the mouth of Kymi River and it is part of the Kymenlaakso region in southern Finland. The municipality has a population of and covers an area of of which is water....

) on the Finnish
Grand Duchy of Finland
The Grand Duchy of Finland was the predecessor state of modern Finland. It existed 1809–1917 as part of the Russian Empire and was ruled by the Russian czar as Grand Prince.- History :...

 coast. Later Popov experimented with ship-to-shore communication. Popov died in 1905 and his claim was not pressed by the Russian government until 1945.

Baviera


In May–June 1899, Julio Cervera Baviera
Julio Cervera Baviera
Julio Cervera Baviera was a Spanish engineer, pioneer in the development of radio, educator, explorer, and military man. He also authored various scientific and geographic books and articles.-Education:...

 worked to develop his own system. After visiting Marconi’s radiotelegraphic installations on the English Channel, he began collaborating with Marconi on resolving the problem of a wireless communication system, obtaining some patents by the end of 1899. Cervera, who worked with Marconi and his assistant, George S. Kemp, in 1899, resolved the issues with their wireless telegraph. He obtained his first patents prior to the end of that year.

Marconi


Guglielmo Marconi
Guglielmo Marconi
Guglielmo Marconi was an Italian inventor, known as the father of long distance radio transmission and for his development of Marconi's law and a radio telegraph system. Marconi is often credited as the inventor of radio, and indeed he shared the 1909 Nobel Prize in Physics with Karl Ferdinand...

 studied at the Leghorn Technical School, and acquainted himself with the published writings of Professor Augusto Righi
Augusto Righi
Augusto Righi was an Italian physicist and a pioneer in the study of electromagnetism. He was born and died in Bologna.His early research, conducted in Bologna between 1872 and 1880, was primarily in electrostatics...

 of the University of Bologna
University of Bologna
The Alma Mater Studiorum - University of Bologna is the oldest continually operating university in the world, the word 'universitas' being first used by this institution at its foundation. The true date of its founding is uncertain, but believed by most accounts to have been 1088...

. In 1894, Sir William Preece deliver a paper to the Royal Institution in London on electric signalling without wires. In 1894 at the Royal Institution lectures, Lodge delivers "The Work of Hertz and Some of His Successors". Marconi is said to have read, while on vacation in 1894, about the experiments that Hertz did in the 1880s. Marconi also read about Tesla's work. It was at this time that Marconi began to understand that radio waves could be used for wireless communications. Marconi's early apparatus was a development of Hertz’s laboratory apparatus into a system designed for communications purposes. At first Marconi used a transmitter to ring a bell in a receiver in his attic laboratory. He then moved his experiments out-of-doors on the family estate near Bologna, Italy, to communicate further. He replaced Hertz’s vertical dipole with a vertical wire topped by a metal sheet, with an opposing terminal connected to the ground. On the receiver side, Marconi replaced the spark gap with a metal powder coherer, a detector developed by Edouard Branly
Edouard Branly
Édouard Eugène Désiré Branly was a French inventor, physicist and professor at the Institut Catholique de Paris. He is primarily known for his early involvement in wireless telegraphy and his invention of the Branly coherer around 1890.-Biography:The coherer was the first widely used detector for...

 and other experimenters. Marconi transmitted radio signals for about 1 miles (1.6 km) at the end of 1895.

By 1896, Marconi introduced to the public a device in London
London
London is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...

, asserting it was his invention. Despite Marconi's statements to the contrary, though, the apparatus resembles Tesla's descriptions in his research, demonstrations and patents. Marconi's later practical four-tuned system was pre-dated by N. Tesla, Oliver Lodge, and J. S. Stone. He filed a patent on his earliest system with the British Patent Office on June 2, 1896.

Marconi was awarded a patent for radio with British patent No. 12,039, Improvements in Transmitting Electrical Impulses and Signals and in Apparatus There-for. The complete specification was filed March 2, 1897. This was Marconi's initial patent for the radio, though it used various earlier techniques of various other experimenters (primarily Tesla) and resembled the instrument demonstrated by others (including Popov). During this time spark-gap wireless telegraphy was widely researched. In July, 1896, Marconi got his invention and new method of telegraphy to the attention of Preece, then engineer-in-chief to the British Government Telegraph Service, who had for the previous twelve years interested himself in the development of wireless telegraphy by the inductive-conductive method. On June 4, 1897, he delievers "Signalling through Space without Wires". Preece devoted considerable time to exhibiting and explaining the Marconi apparatus at the Royal Institution
Royal Institution
The Royal Institution of Great Britain is an organization devoted to scientific education and research, based in London.-Overview:...

 in London, stating that Marconi invented a new relay which had high sensitiveness and delicacy.
In 1896, Bose went to London on a lecture tour and met Marconi, who was conducting wireless experiments for the British post office. The Marconi Company Ltd. was founded by Marconi in 1897, known as the Wireless Telegraph Trading Signal Company. Also in 1897, Marconi established the radio station at Niton, Isle of Wight
Niton, Isle of Wight
Niton is a village on the Isle of Wight, near Ventnor with a thriving population of 1142, supporting two pubs, several churches,a pottery workshop/shop, a pharmacy and 3 local shops including a post office...

, England. Marconi's wireless telegraphy was inspected by the Post Office Telegraph authorities; they made a series of experiments with Marconi's system of telegraphy without connecting wires, in the Bristol Channel
Bristol Channel
The Bristol Channel is a major inlet in the island of Great Britain, separating South Wales from Devon and Somerset in South West England. It extends from the lower estuary of the River Severn to the North Atlantic Ocean...

. The October wireless signals of 1897 were sent from Salisbury Plain
Salisbury Plain
Salisbury Plain is a chalk plateau in central southern England covering . It is part of the Southern England Chalk Formation and largely lies within the county of Wiltshire, with a little in Hampshire. The plain is famous for its rich archaeology, including Stonehenge, one of England's best known...

 to Bath, a distance of 34 miles (54.7 km). Marconi's reputation is largely based on the making of his law
Marconi's law
Marconi's law is the relation between height of antennae and maximum signalling distance. Guglielmo Marconi enunciated at one time an empirical law that, for simple vertical sending and receiving antennae of equal height, the maximum working telegraphic distance varied as the square of the height...

 (1897), and other accomplishments in radio communications and commercializing a practical system.

Other experimental stations were established at Lavernock Point, near Penarth
Penarth
Penarth is a town and seaside resort in the Vale of Glamorgan , Wales, 5.2 miles south west from the city centre of the Welsh capital city of Cardiff and lying on the north shore of the Severn Estuary at the southern end of Cardiff Bay...

; on the Flat Holmes, an island in mid-channel, and at Brean Down
Brean Down
Brean Down is a promontory off the coast of Somerset standing high and extending into the Bristol Channel at the eastern end of Bridgwater Bay between Weston-super-Mare and Burnham-on-Sea....

, a promontory
Promontory
Promontory may refer to:*Promontory, a prominent mass of land which overlooks lower lying land or a body of water*Promontory, Utah, the location where the United States first Transcontinental Railroad was completed...

 on the Somerset
Somerset
The ceremonial and non-metropolitan county of Somerset in South West England borders Bristol and Gloucestershire to the north, Wiltshire to the east, Dorset to the south-east, and Devon to the south-west. It is partly bounded to the north and west by the Bristol Channel and the estuary of the...

 side. Signals were obtained between the first and last-named points, a distance of, approximately, 8 miles (12.9 km). The receiving instrument used was a Morse inkwriter of the Post Office pattern. In 1898, Marconi opened a radio factory in Hall Street, Chelmsford, England, employing around 50 people. In 1899, Marconi announced his invention of the "iron-mercury-iron coherer with telephone detector" in a paper presented at Royal Society, London.

In May, 1898, communication was established for the Corporation of Lloyds
Lloyd's of London
Lloyd's, also known as Lloyd's of London, is a British insurance and reinsurance market. It serves as a partially mutualised marketplace where multiple financial backers, underwriters, or members, whether individuals or corporations, come together to pool and spread risk...

 between Ballycastle
Ballycastle, County Antrim
Ballycastle is a small town in County Antrim in Northern Ireland. Its population was 5,089 people in the 2001 Census. It is the seat and main settlement of Moyle District Council....

 and the Lighthouse
Lighthouse
A lighthouse is a tower, building, or other type of structure designed to emit light from a system of lamps and lenses or, in older times, from a fire, and used as an aid to navigation for maritime pilots at sea or on inland waterways....

 on Rathlin Island
Rathlin Island
Rathlin Island is an island off the coast of County Antrim, and is the northernmost point of Northern Ireland. Rathlin is the only inhabited offshore island in Northern Ireland, with a rising population of now just over 100 people, and is the most northerly inhabited island off the Irish coast...

 in the North of Ireland. In July, 1898, the Marconi telegraphy was employed to report the results of yacht races at the Kingston Regatta
Kingston Regatta
Kingston Regatta is a rowing regatta, on the River Thames in England which takes place at Kingston upon Thames, Surrey on the reach above Teddington Lock....

 for the Dublin Express
Daily Express (Dublin)
The Daily Express of Dublin was an Irish newspaper published from 1851 until June 1921, and then continued for registration purposes until 1960.It was a unionist newspaper. From 1917, its title was the Daily Express and Irish Daily Mail...

 newspaper. A set of instruments were fitted up in a room at Kingstown, and another on board a steamer, the Flying Huntress. The aerial conductor on shore was a strip of wire netting attached to a mast 40 feet (12.2 m) high, and several hundred messages were sent and correctly received during the progress of the races.

At this time His Majesty King Edward VII, then Prince of Wales
Prince of Wales
Prince of Wales is a title traditionally granted to the heir apparent to the reigning monarch of the United Kingdom of Great Britain and Northern Ireland and the 15 other independent Commonwealth realms...

, had the misfortune to injure his knee, and was confined on board the royal yacht Osltorm in Cowes Bay.
Marconi fitted up his apparatus on board the royal yacht by request, and also at Osborne House
Osborne House
Osborne House is a former royal residence in East Cowes, Isle of Wight, UK. The house was built between 1845 and 1851 for Queen Victoria and Prince Albert as a summer home and rural retreat....

, Isle of Wight, and kept up wireless communication for three weeks between these stations. The distances covered were small; but as the yacht moved about, on some occasions high hills were interposed, so that the aerial wires were overtopped by hundreds of feet, yet this was no obstacle to communication. These demonstrations led the Corporation of Trinity House to afford an opportunity for testing the system in practice between the South Foreland Lighthouse
South Foreland Lighthouse
South Foreland Lighthouse is a Victorian lighthouse on the South Foreland in St. Margaret's Bay, Dover, Kent, England, used to warn ships approaching the nearby Goodwin Sands. It went out of service in 1988 and is currently owned by the National Trust...

, near Dover, and the East Goodwin Lightship, on the Goodwin Sands
Goodwin Sands
The Goodwin Sands is a 10-mile-long sand bank in the English Channel, lying six miles east off Deal in Kent, England. The Brake Bank lying shorewards is part of the same geological unit. As the shoals lie close to major shipping channels, more than 2,000 ships are believed to have been wrecked...

. This installation was set in operation on December 24, 1898, and proved to be of value. It was shown that when once the apparatus was set up it could be worked by ordinary seamen with very little training.

At the end of 1898 electric wave telegraphy established by Marconi had demonstrated its utility, especially for communication between ship and ship and ship and shore. Electric wave telegraphy had the advantages as follows:
  • Transmission worked as well by night as by day, and in bad weather, fogs, or storms, as well as in fair weather; provided that the proper insulation of the aerial wire or elevated conductor was maintained.
  • In certain electrical conditions of the atmosphere, and during thunderstorms, some difficulty was usually found in working, owing to the atmospheric discharges affecting the sensitive tube, and therefore making stray marks on the Morse tape of the printer, but seldom sufficient to interrupt communication altogether.
  • The interposition of high hills, trees, or the curvature of the earth did not prevent communication, though slightly affecting the power required. It worked particularly well over sea surface, and between ships and shore stations.
  • The apparatus could be set up and handled by any ordinary telegraphist, and the record was made on paper strip in the usual Morse code.
  • Transmission easily covered distances far beyond those feasible or attained by other systems of wireless telegraphy.
  • Lastly, the apparatus required was by no means costly, and, with the exception of the mast required for upholding the aerial wire, it occupied but little space, and was particularly adapted for use on board ship.


The Haven Hotel
Haven Hotel
The Haven Hotel is an AA four star hotel in Sandbanks, near Poole, Dorset on the south coast of England.-History:The first hotel built on this location was the North Haven Inn in 1838. The Inn was demolished and replaced with the present Haven Hotel in 1887...

 station and Wireless Telegraph Mast was where much of Marconi's research work on wireless telegraphy was carried out after 1898. In 1899, he transmitted messages across the English Channel
English Channel
The English Channel , often referred to simply as the Channel, is an arm of the Atlantic Ocean that separates southern England from northern France, and joins the North Sea to the Atlantic. It is about long and varies in width from at its widest to in the Strait of Dover...

. Also in 1899, Marconi delivered "Wireless Telegraphy" to the Institution of Electrical Engineers
Institution of Electrical Engineers
The Institution of Electrical Engineers was a British professional organisation of electronics, electrical, manufacturing, and Information Technology professionals, especially electrical engineers. The I.E.E...

. In addition, in 1899, W. H. Preece delivers "Aetheric Telegraphy", stating that the experimental stage in wireless telegraphy had been passed in 1894 and inventors were then entering the commercial stage. Preece, continuing in the lecture, details the work of Marconi and other British inventors. In October, 1899, the progress of the yachts in the international race
America's Cup
The America’s Cup is a trophy awarded to the winner of the America's Cup match races between two yachts. One yacht, known as the defender, represents the yacht club that currently holds the America's Cup and the second yacht, known as the challenger, represents the yacht club that is challenging...

 between the Columbia and Shamrock was successfully reported by aerial telegraphy, as many as 4,000 words having been (as is said) despatched from the two ship stations to the shore stations. Immediately afterward the apparatus was placed by request at the service of the United States Navy Board, and some highly interesting experiments followed under Marconi's personal supervision. The Marconi Company was renamed Marconi's Wireless Telegraph Company in 1900.


In 1901, Marconi claimed to have received daytime transatlantic radio frequency signals at a wavelength of 366 metres
Medium frequency
Medium frequency refers to radio frequencies in the range of 300 kHz to 3 MHz. Part of this band is the medium wave AM broadcast band. The MF band is also known as the hectometer band or hectometer wave as the wavelengths range from ten down to one hectometers...

 (820 kHz). Marconi established a wireless transmitting station at Marconi House, Rosslare Strand, Co. Wexford in 1901 to act as a link between Poldhu in Cornwall and Clifden in Co. Galway. His announcement on 12 December 1901, using a 152.4 metres (500 ft) kite-supported antenna for reception, stated a the message was received at Signal Hill in St John's
St. John's, Newfoundland and Labrador
St. John's is the capital and largest city in Newfoundland and Labrador, and is the oldest English-founded city in North America. It is located on the eastern tip of the Avalon Peninsula on the island of Newfoundland. With a population of 192,326 as of July 1, 2010, the St...

, Newfoundland
Newfoundland and Labrador
Newfoundland and Labrador is the easternmost province of Canada. Situated in the country's Atlantic region, it incorporates the island of Newfoundland and mainland Labrador with a combined area of . As of April 2011, the province's estimated population is 508,400...

 (now part of Canada) via signals transmitted by the company's new high-power station at Poldhu
Poldhu
Poldhu is a small area in south Cornwall, England, UK, situated on the Lizard Peninsula; it comprises Poldhu Point and Poldhu Cove. It lies on the coast west of Goonhilly Downs, with Mullion to the south and Porthleven to the north...

, Cornwall
Cornwall
Cornwall is a unitary authority and ceremonial county of England, within the United Kingdom. It is bordered to the north and west by the Celtic Sea, to the south by the English Channel, and to the east by the county of Devon, over the River Tamar. Cornwall has a population of , and covers an area of...

. The message received was the Morse letter 'S' - three dots. Bradford has recently contested this, however, based on theoretical work as well as a reenactment of the experiment; it is possible that what was heard was only random atmospheric noise, which was mistaken for a signal, or that Marconi may have heard a shortwave
Shortwave
Shortwave radio refers to the upper MF and all of the HF portion of the radio spectrum, between 1,800–30,000 kHz. Shortwave radio received its name because the wavelengths in this band are shorter than 200 m which marked the original upper limit of the medium frequency band first used...

 harmonic
Harmonic
A harmonic of a wave is a component frequency of the signal that is an integer multiple of the fundamental frequency, i.e. if the fundamental frequency is f, the harmonics have frequencies 2f, 3f, 4f, . . . etc. The harmonics have the property that they are all periodic at the fundamental...

 of the signal. The distance between the two points was about 3500 kilometres (2,174.8 mi).

The Poldhu
Poldhu
Poldhu is a small area in south Cornwall, England, UK, situated on the Lizard Peninsula; it comprises Poldhu Point and Poldhu Cove. It lies on the coast west of Goonhilly Downs, with Mullion to the south and Porthleven to the north...

 to Newfoundland transmission claim has been criticized. There are various science historians, such as Belrose and Bradford, who have cast doubt that the Atlantic was bridged in 1901, but other science historians have taken the position that this was the first transatlantic radio transmission. Critics have claimed that it is more likely that Marconi received stray atmospheric noise from atmospheric electricity
Atmospheric electricity
Atmospheric electricity is the regular diurnal variations of the Earth's atmospheric electromagnetic network . The Earth's surface, the ionosphere, and the atmosphere is known as the global atmospheric electrical circuit...

 in this experiment. The transmitting station in Poldhu, Cornwall used a spark-gap transmitter that could produce a signal in the medium frequency range and with high power levels.

Marconi transmitted from England to Canada and the United States. In this period, a particular electromagnetic receiver, called the Marconi magnetic detector or hysteresis magnetic detector, was developed further by Marconi and was successfully used in his early transatlantic work (1902) and in many of the smaller stations for a number of years. In 1902, a Marconi station
Marconi Station
The Marconi Wireless Corporation operated numerous pioneering radio stations in Canada, Ireland, Newfoundland, the United States, the United Kingdom and a number of other locations around the world.-Australia:...

 was established in the village of Crookhaven
Crookhaven
Crookhaven is a village in County Cork, Ireland, on the most southwestern tip of Ireland. A winter population of about forty swells in the summer to about four hundred with the occupants of the many holiday homes arriving.-History:...

, County Cork
County Cork
County Cork is a county in Ireland. It is located in the South-West Region and is also part of the province of Munster. It is named after the city of Cork . Cork County Council is the local authority for the county...

, Ireland
Ireland
Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...

 to provide marine radio communications to ships arriving from the Americas. A ship's master could contact shipping line agents ashore to enquire which port was to receive their cargo without the need to come ashore at what was the first port of landfall. Ireland was also, due to its western location, to play a key role in early efforts to send trans-Atlantic messages. Marconi transmitted from his station in Glace Bay, Nova Scotia, Canada across the Atlantic, and on 18 January 1903 a Marconi station sent a message of greetings from Theodore Roosevelt
Theodore Roosevelt
Theodore "Teddy" Roosevelt was the 26th President of the United States . He is noted for his exuberant personality, range of interests and achievements, and his leadership of the Progressive Movement, as well as his "cowboy" persona and robust masculinity...

, the President of the United States, to the King of the United Kingdom, marking the first transatlantic radio transmission originating in the United States

In 1904, Marconi opened the ocean daily newspaper, the Cunard Daily Bulletin, on the R.M.S.
Royal Mail Ship
Royal Mail Ship , usually seen in its abbreviated form RMS, a designation which dates back to 1840, is the ship prefix used for seagoing vessels that carry mail under contract by Royal Mail...

 "Campania
RMS Campania
RMS Campania was a British ocean liner owned by the Cunard Steamship Line Shipping Company, built by Fairfield Shipbuilding and Engineering Company of Govan, Scotland, and launched on Thursday, 8 September 1891....

." At the start, the passing events were printed in a little pamphlet of four pages called the Cunard Bulletin. The title would read Cunard Daily Bulletin, with subheads for "Marconigrams Direct to the Ship." All the passenger ships of the Cunard Company are fitted with Marconi's system of wireless telegraphy, by means of which constant communication was kept up, either with other ships or with land stations on the eastern or western hemisphere. The RMS Lucania
RMS Lucania
RMS Lucania was a British ocean liner owned by the Cunard Steamship Line Shipping Company, built by Fairfield Shipbuilding and Engineering Company of Govan, Scotland, and launched on Thursday, 2 February 1893....

, Oct., 1903, with Marconi on board, was the first vessel to hold communication with both sides of the Atlantic. The Cunard Daily Bulletin, a thirty-two page illustrated paper published on board these boats, recorded news received by wireless telegraphy, and is first ocean newspaper. In August, 1903, in agreement was made with the British Government by which the Cunard Co. were to build two steamers, to be, with all other Cunard ships, at the disposal of the British Admiralty for hire or purchase whenever they may be required, the Government lending the company £2,600,000 to build the ships and granting them a subsidy £150,000 a year. One was the RMS Lusitania
RMS Lusitania
RMS Lusitania was a British ocean liner designed by Leonard Peskett and built by John Brown and Company of Clydebank, Scotland. The ship entered passenger service with the Cunard Line on 26 August 1907 and continued on the line's heavily-traveled passenger service between Liverpool, England and New...

 and the RMS Mauritania
RMS Mauretania (1906)
RMS Mauretania was an ocean liner designed by Leonard Peskett and built by Swan, Hunter & Wigham Richardson at Wallsend, Tyne and Wear for the British Cunard Line, and launched on 20 September 1906. At the time, she was the largest and fastest ship in the world. Mauretania became a favourite among...

.

In June and July 1923, Marconi's shortwave
Shortwave
Shortwave radio refers to the upper MF and all of the HF portion of the radio spectrum, between 1,800–30,000 kHz. Shortwave radio received its name because the wavelengths in this band are shorter than 200 m which marked the original upper limit of the medium frequency band first used...

 transmissions were completed during nights on 97 meters from Poldhu Wireless Station
Poldhu
Poldhu is a small area in south Cornwall, England, UK, situated on the Lizard Peninsula; it comprises Poldhu Point and Poldhu Cove. It lies on the coast west of Goonhilly Downs, with Mullion to the south and Porthleven to the north...

, Cornwall
Cornwall
Cornwall is a unitary authority and ceremonial county of England, within the United Kingdom. It is bordered to the north and west by the Celtic Sea, to the south by the English Channel, and to the east by the county of Devon, over the River Tamar. Cornwall has a population of , and covers an area of...

, to his yacht Elettra in the Cape Verde Islands
Cape Verde
The Republic of Cape Verde is an island country, spanning an archipelago of 10 islands located in the central Atlantic Ocean, 570 kilometres off the coast of Western Africa...

. In September 1924, Marconi transmitted during daytime and nighttime on 32 meters from Poldhu to his yacht in Beirut
Beirut
Beirut is the capital and largest city of Lebanon, with a population ranging from 1 million to more than 2 million . Located on a peninsula at the midpoint of Lebanon's Mediterranean coastline, it serves as the country's largest and main seaport, and also forms the Beirut Metropolitan...

. Marconi, in July 1924, entered into contracts with the British General Post Office (GPO) to install telegraphy circuits from London to Australia, India, South Africa and Canada as the main element of the Imperial Wireless Chain
Imperial Wireless Chain
The Imperial Wireless Chain, also known as the Empire Wireless Chain, was a strategic international wireless telegraphy communications network, created to link the countries of the British Empire. Although the idea was conceived prior to World War I, Britain was the last of the world's Great Powers...

. The UK-to-Canada shortwave "Beam Wireless Service" went into commercial operation on 25 October 1926. Beam Wireless Services from the UK to Australia, South Africa and India went into service in 1927. Electronic components for the system were built at Marconi's New Street wireless factory in Chelmsford
Chelmsford
Chelmsford is the county town of Essex, England and the principal settlement of the borough of Chelmsford. It is located in the London commuter belt, approximately northeast of Charing Cross, London, and approximately the same distance from the once provincial Roman capital at Colchester...

.

Marconi would jointly receive the 1909 Nobel Prize in Physics
Nobel Prize in Physics
The Nobel Prize in Physics is awarded once a year by the Royal Swedish Academy of Sciences. It is one of the five Nobel Prizes established by the will of Alfred Nobel in 1895 and awarded since 1901; the others are the Nobel Prize in Chemistry, Nobel Prize in Literature, Nobel Peace Prize, and...

 with Karl Ferdinand Braun
Karl Ferdinand Braun
Karl Ferdinand Braun was a German inventor, physicist and Nobel laureate in physics. Braun contributed significantly to the development of the radio and television technology: he shared with Guglielmo Marconi the 1909 Nobel Prize in Physics.-Biography:Braun was born in Fulda, Germany, and...

 for contributions to the existing radio sciences. Marconi's demonstrations of the use of radio for wireless communications, equipping ships with life saving wireless communications, establishing the first transatlantic radio service, and building the first stations for the British short wave service, have marked his place in history. Shortly after the turn of the 20th century, the US Patent Office re-awarded Marconi a patent for radio. The was granted on June 4, 1901. Marconi's was awarded on June 11, 1901, also. This system was more advanced than his previous works. In 1943, a lawsuit regarding Marconi's early United States radio patents were resolved by the United States Supreme Court, who overturned most of these.

Naval wireless


The United States Navy Board had issued a 1899 report on the results of investigations of the Marconi system of wireless telegraphy. The report, Notes On The Marconi Wireless Telegraphy was published in full in the Electrician, and from it the following statements concerning the efficiency of the system have been taken: It was well adapted for use in squadron signalling under conditions of rain, fog, darkness and motion of speed. Wind, rain, fog, and other conditions of weather do not affect the transmission through space, but dampness may reduce the range, rapidity, and accuracy by impairing the insulation of the aerial wire and the instruments. Darkness has no effect. When two transmitters are sending at the same time, all the receiving wires within range receive the impulses from transmitters, and the tapes, although unreadable, show unmistakably that such double sending was taking place. In every case, under a great number of varied conditions, the attempted interference was complete. Marconi, although he stated to the Board before these attempts were made that he could prevent interference, never explained how nor made any attempt to demonstrate that it could be done. Between large ships (heights of masts 130 feet (39.6 m) and 140 feet (42.7 m)) and a torpedo-boat (height of mast 45 feet (13.7 m)), across open water, signals can be read up to 7 miles (11.3 km) on the torpedo-boat and 85 miles (136.8 km) on the ship
Naval ship
A naval ship is a ship used for combat purposes, commonly by a navy. Naval ships are differentiated from civilian ships by construction and purpose...

. Communication might be interrupted altogether when tall buildings of iron framing intervene. The rapidity was not greater than twelve words per minute for skilled operators. The sending apparatus and wire would injuriously affect the compass if placed near it. The exact distance were not known, and would be determined by experiment. The system was adapted for use on all vessels of the navy, including torpedo-boats and small vessels, as patrol boat
Patrol boat
A patrol boat is a relatively small naval vessel generally designed for coastal defense duties.There have been many designs for patrol boats. They may be operated by a nation's navy, coast guard, or police force, and may be intended for marine and/or estuarine or river environments...

s, scout boats, and despatch boats, but it was impracticable in a small boat. For landing parties the only feasible method of use would be to erect a pole on shore
Antenna (radio)
An antenna is an electrical device which converts electric currents into radio waves, and vice versa. It is usually used with a radio transmitter or radio receiver...

 and then communicate with the ship. The system could be adapted to the telegraphic determination of differences of longitude
Longitude
Longitude is a geographic coordinate that specifies the east-west position of a point on the Earth's surface. It is an angular measurement, usually expressed in degrees, minutes and seconds, and denoted by the Greek letter lambda ....

 in surveying
Surveying
See Also: Public Land Survey SystemSurveying or land surveying is the technique, profession, and science of accurately determining the terrestrial or three-dimensional position of points and the distances and angles between them...

. The Board respectfully recommended that the system be given a trial in the United States Navy
United States Navy
The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...

.

The HMS Hector
HMS Hector (1862)
HMS Hector was the lead ship of the armoured frigates ordered by the Royal Navy in 1861. Upon completion in 1864 she was assigned to the Channel Fleet. The ship was paid off in 1867 to refit and be re-armed. Upon recommissioning in 1868 she was assigned as the guard ship of the Fleet Reserve in...

became the first British warship to have wireless telegraphy
Wireless telegraphy
Wireless telegraphy is a historical term used today to apply to early radio telegraph communications techniques and practices, particularly those used during the first three decades of radio before the term radio came into use....

 installed when she conducted the first trials of the new equipment for the Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

. Starting in December 1899, the HMS Hector and HMS Jaseur were outfitted with wireless equipment. In 1901, HMS Jaseur
HMS Jaseur
Six ships of the Royal Navy have borne the name HMS Jaseur, the name coming from the French for the Waxwing. was a 12-gun brig-sloop that captured off the Andaman Islands in 1807. was a Cruizer-class brig-sloop launched in 1813 and sold in 1847. was a wood screw gunboat launched in 1857 and...

 received signals from the Marconi transmitter on the Isle of Wight and from the HMS Hector (25 January).

Stone Stone


John Stone Stone
John Stone Stone
John Stone Stone was an American mathematician, physicist and inventor. He labored as an early telephone engineer, was influential in developing wireless communication technology, and holds dozens of key patents in the field of "space telegraphy".-Early years:Stone was born in Dover, now Manakin...

 labored as an early telephone engineer and was influential in developing wireless communication technology, and holds dozens of key patent
Patent
A patent is a form of intellectual property. It consists of a set of exclusive rights granted by a sovereign state to an inventor or their assignee for a limited period of time in exchange for the public disclosure of an invention....

s in the field of "space telegraphy". Patents of Stone for radio, together with their equivalents in other countries, form a very voluminous contribution to the patent literature of the subject. More than seventy United States patents have been granted to this patentee alone. In many cases these specifications are learned contributions to the literature of the subject, filled with valuable references to other sources of information. A complete analysis of Stone's specifications would occupy too much space. Broadly speaking, they may be divided into four classes:
  • Those concerned with proposed methods for the achievement of syntonic telegraphy, or the isolation of receiving stations or protection of receivers from the action of vagrant waves.
  • Those describing forms of electric wave detector or cymoscope.
  • Those covering the construction of various forms of transmitting
    Transmitter
    In electronics and telecommunications a transmitter or radio transmitter is an electronic device which, with the aid of an antenna, produces radio waves. The transmitter itself generates a radio frequency alternating current, which is applied to the antenna. When excited by this alternating...

     and receiving circuit
    Receiver (radio)
    A radio receiver converts signals from a radio antenna to a usable form. It uses electronic filters to separate a wanted radio frequency signal from all other signals, the electronic amplifier increases the level suitable for further processing, and finally recovers the desired information through...

    , and the production of continuous trains of wave
    Continuous wave
    A continuous wave or continuous waveform is an electromagnetic wave of constant amplitude and frequency; and in mathematical analysis, of infinite duration. Continuous wave is also the name given to an early method of radio transmission, in which a carrier wave is switched on and off...

    s.
  • Miscellaneous specifications covering devices proposed for localizing the direction of the arriving waves and other matters.


Stone has had issued to him a large number of patents embracing a method for impressing oscillations on a radiator system and emitting the energy in the form of waves of predetermined length whatever may be the electrical dimensions of the oscillator. On February 8, 1900, he filed for a selective system in . In this system, two simple circuits are associated inductively, each having an independent degree of freedom, and in which the restoration of electric oscillations to zero potential the currents are superimposed, giving rise to compound harmonic currents which permit the resonator system to be syntonized with precision to the oscillator. Stone's system, as stated in , developed free or unguided simple harmonic electromagnetic signal waves of a definite frequency to the exclusion of the energy of signal waves of other frequencies, and an elevated conductor and means for developing therein forced simple electric vibrations of corresponding frequency. In these patents Stone devised a multiple inductive oscillation circuit with the object of forcing on the antenna circuit a single oscillation of definite frequency. In the system for receiving the energy of free or unguided simple harmonic electromagnetic signal waves of a definite frequency to the exclusion of the energy of signal waves of other frequencies, he claimed an elevated conductor and a resonant circuit associated with said conductor and attuned to the frequency of the waves, the energy of which is to be received. A coherer made on what is called the Stone system was employed in some of the portable wireless outfits of the United States Army
United States Army
The United States Army is the main branch of the United States Armed Forces responsible for land-based military operations. It is the largest and oldest established branch of the U.S. military, and is one of seven U.S. uniformed services...

. The Stone Coherer has two small steel plugs between which are placed loosely packed carbon granules. This is a self-decohering device; though not as sensitive as other forms of detectors it is well suited to the rough usage of portable outfits.

Fessenden


In late 1886, Reginald A. Fessenden began working directly for Thomas Edison at the inventor's new laboratory in West Orange, New Jersey
West Orange, New Jersey
West Orange is a township in central Essex County, New Jersey, United States. As of the 2010 United States Census, the township population was 46,207...

. Fessenden quickly made major advances, especially in receiver design, as he worked to develop audio reception of signals. Fessenden's initial United States patents were and and are companion patents. One concerns the methods and the other the devices of the same system. The United States Weather Bureau began, early in 1900, a systematic course of experimentation in wireless telegraphy, employing him as a specialist. Fessenden evolved the heterodyne
Heterodyne
Heterodyning is a radio signal processing technique invented in 1901 by Canadian inventor-engineer Reginald Fessenden where high frequency signals are converted to lower frequencies by combining two frequencies. Heterodyning is useful for frequency shifting information of interest into a useful...

 principle here where two signals combined to produce a third audible tone.

In 1900, construction began on a large radio transmitting dynamo. Fessenden, experimenting with a high-frequency spark transmitter, successfully transmitted speech on December 23, 1900 over a distance of about 1.6 kilometre (0.994196378639691 mi), the first audio radio transmission. Early in 1901 the Weather Bureau officially installed Fessenden at Wier's Point, Roanoke Island
Roanoke Island
Roanoke Island is an island in Dare County near the coast of North Carolina, United States. It was named after the historical Roanoke Carolina Algonquian people who inhabited the area in the 16th century at the time of English exploration....

, North Carolina
North Carolina
North Carolina is a state located in the southeastern United States. The state borders South Carolina and Georgia to the south, Tennessee to the west and Virginia to the north. North Carolina contains 100 counties. Its capital is Raleigh, and its largest city is Charlotte...

, and he made experimental transmissions across water to a station located about 5 miles (8 km) west of Cape Hatteras
Cape Hatteras
Cape Hatteras is a cape on the coast of North Carolina. It is the point that protrudes the farthest to the southeast along the northeast-to-southwest line of the Atlantic coast of North America...

, the distance between the two stations being almost exactly 50 miles (80.5 km). A dynamo of 1 kW output at 10 kilohertz was built in 1902. The credit for the development of this machine is due to Charles Proteus Steinmetz
Charles Proteus Steinmetz
Charles Proteus Steinmetz was a German-American mathematician and electrical engineer. He fostered the development of alternating current that made possible the expansion of the electric power industry in the United States, formulating mathematical theories for engineers...

, Caryl D. Haskins, Ernst Alexanderson
Ernst Alexanderson
Ernst Frederick Werner Alexanderson was a Swedish-American electrical engineer, who was a pioneer in radio and television development.-Background:...

, John T. H. Dempster, Henry Geisenhoner, Adam Stein, Jr., and F. P. Mansbendel.

In a paper written by Fessenden in 1902, it was asserted that important advances had been made, one of which was overcoming largely the loss of energy experienced in other systems. He also declared that syntony was not safely selecting,
Within the history of radio
History of radio
The early history of radio is the history of technology that produced radio instruments that use radio waves. Within the timeline of radio, many people contributed theory and inventions in what became radio. Radio development began as "wireless telegraphy"...

, several people were involved in the invention of radio and there were many key inventions in what became the modern systems of wireless
Wireless
Wireless telecommunications is the transfer of information between two or more points that are not physically connected. Distances can be short, such as a few meters for television remote control, or as far as thousands or even millions of kilometers for deep-space radio communications...

. Radio
Radio
Radio is the transmission of signals through free space by modulation of electromagnetic waves with frequencies below those of visible light. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space...

 development began as "wireless telegraphy
Wireless telegraphy
Wireless telegraphy is a historical term used today to apply to early radio telegraph communications techniques and practices, particularly those used during the first three decades of radio before the term radio came into use....

". During the early development of wireless technology, and continuing long after its widespread adoption, disputes persisted as to who could claim credit for the invention of radio. The matter was important for economic, political and nationalistic reasons.

Physics of wireless signalling


Various scientists proposed that electricity and magnetism
Electromagnetism
Electromagnetism is one of the four fundamental interactions in nature. The other three are the strong interaction, the weak interaction and gravitation...

 were linked. In 1802 Gian Domenico Romagnosi
Gian Domenico Romagnosi
Gian Domenico Romagnosi was an Italian philosopher, economist and jurist.-Biography:Gian Domenico Romagnosi was born in Salsomaggiore Terme....

 suggested the relationship between electric current and magnetism but his reports went unnoticed. In 1820 Hans Christian Ørsted
Hans Christian Ørsted
Hans Christian Ørsted was a Danish physicist and chemist who discovered that electric currents create magnetic fields, an important aspect of electromagnetism...

 performed a simple and today widely known experiment on man-made electric current and magnetism. He demonstrated that a wire carrying a current could deflect a magnetized compass
Compass
A compass is a navigational instrument that shows directions in a frame of reference that is stationary relative to the surface of the earth. The frame of reference defines the four cardinal directions – north, south, east, and west. Intermediate directions are also defined...

 needle. Ørsted's work influenced André-Marie Ampère
André-Marie Ampère
André-Marie Ampère was a French physicist and mathematician who is generally regarded as one of the main discoverers of electromagnetism. The SI unit of measurement of electric current, the ampere, is named after him....

 to produce a theory of electromagnetism.

Several different electrical, magnetic or electromagnetic physical phenomena can be used to transmit signals over a distance without intervening wires. The various methods for wireless signal transmissions include:
  • Electrical conduction through the ground, or through water.
  • Magnetic induction
    Electromagnetic induction
    Electromagnetic induction is the production of an electric current across a conductor moving through a magnetic field. It underlies the operation of generators, transformers, induction motors, electric motors, synchronous motors, and solenoids....

  • Capacitive coupling
    Capacitive coupling
    In electronics, capacitive coupling is the transfer of energy within an electrical network by means of the capacitance between circuit nodes. This coupling can have an intentional or accidental effect...

  • Electromagnetic waves
    Electromagnetic radiation
    Electromagnetic radiation is a form of energy that exhibits wave-like behavior as it travels through space...


All these physical phenomena, as well as various other ideas such as conduction through air, were tested for the purpose of communication. Early researchers may not have understood or disclosed which physical effects were responsible for transmitting signals. Early experiments used the existing theories of the movement of charged particles through an electrical conductor. There was no theory of electromagnetic wave propagation to guide experiments before Maxwell's treatise and its verification by Hertz and others.

Capacitive and inductive coupling systems today are used only for short-range special purpose systems. The physical phenomenon used today for long-distance wireless communications involves the use of modulated electromagnetic waves, which is radio.

Radio antennas radiate electromagnetic waves that can reach the receiver
Radio propagation
Radio propagation is the behavior of radio waves when they are transmitted, or propagated from one point on the Earth to another, or into various parts of the atmosphere...

 either by ground wave propagation, by refraction from the ionosphere, known as sky wave propagation, and occasionally by refraction in lower layers of the atmosphere (tropospheric ducting). The ground wave component is the portion of the radiated electromagnetic wave that propagates close to the Earth's surface. It has both direct-wave and ground-reflected components. The direct-wave is limited only by the distance from the transmitter to the horizon plus a distance added by diffraction around the curvature of the earth. The ground-reflected portion of the radiated wave reaches the receiving antenna after being reflected from the Earth's surface. A portion of the ground wave energy radiated by the antenna may also be guided by the Earth's surface as a ground-hugging surface wave
Surface wave
In physics, a surface wave is a mechanical wave that propagates along the interface between differing media, usually two fluids with different densities. A surface wave can also be an electromagnetic wave guided by a refractive index gradient...

.

Any change in the electrical conditions of a circuit, whether internal, such as a change of load, starting and switching operations, short circuits, or external, such as due to lightning, involves a readjustment of the stored electromagnetic and electrostatic energy of the circuit; that is, a so-called transient. Such transient is of the general character of a condenser discharge through an inductive circuit. The phenomenon of the condenser discharge through an inductive circuit therefore is of the greatest importance to the engineer, as the foremost cause of high-voltage and high-frequency troubles in electric circuits.

With the development of radio communication—whether wireless or wired—the condenser discharge through an inductive circuit has assumed a great additional importance since, with the exception of a few of the highest power transoceanic stations, which use power-driven high-frequency alternators, the source of power in the radio communication up to 1922 was the condenser discharge through the inductive circuit, whether as a damped wave or as an undamped wave. In undamped wave radio communication, the condenser discharge circuit is coupled with a source of electric power—a battery—in such a manner, that, without interfering with the character of the oscillation, sufficient energy is fed into the circuit to maintain the oscillation, similarly as in the clock, the pendulum is coupled with a source of mechanical power—weight or spring— so as to maintain its oscillation undamped. The usual method of producing a condenser discharge through an inductive circuit is gradually to charge a condenser from a source of electric power, until the condenser voltage has risen sufficiently high to jump a spark gap (the rotary gap, or quenched gap of the damped wave wireless for instance) and thereby discharge through the inductive circuit.

Theory of electromagnetism





Several scientists speculated that light might be connected with electricity or magnetism. Around 1830 Francesco Zantedeschi
Francesco Zantedeschi
Francesco Zantedeschi was an Italian priest and physicist.-Biography:A native of Dolcè, near Verona, Zantedeschi was for some time professor of physics and philosophy in the Liceo of Venice. Later he accepted the chair of physics in the University of Padua, which he held until 1853 being then...

 suggested a connection between light, electricity, and magnetism. In 1832 Joseph Henry
Joseph Henry
Joseph Henry was an American scientist who served as the first Secretary of the Smithsonian Institution, as well as a founding member of the National Institute for the Promotion of Science, a precursor of the Smithsonian Institution. During his lifetime, he was highly regarded...

 performed experiments detecting electromagnetic effects over a distance of 200 feet (61 m) and postulated the existence of electromagnetic waves.

In 1831, Michael Faraday
Michael Faraday
Michael Faraday, FRS was an English chemist and physicist who contributed to the fields of electromagnetism and electrochemistry....

 began a series of experiments in which he discovered electromagnetic induction
Electromagnetic induction
Electromagnetic induction is the production of an electric current across a conductor moving through a magnetic field. It underlies the operation of generators, transformers, induction motors, electric motors, synchronous motors, and solenoids....

. The relation was mathematically modelled by Faraday's law
Faraday's law of induction
Faraday's law of induction dates from the 1830s, and is a basic law of electromagnetism relating to the operating principles of transformers, inductors, and many types of electrical motors and generators...

, which subsequently became one of the four Maxwell equations
Maxwell's equations
Maxwell's equations are a set of partial differential equations that, together with the Lorentz force law, form the foundation of classical electrodynamics, classical optics, and electric circuits. These fields in turn underlie modern electrical and communications technologies.Maxwell's equations...

. Faraday proposed that electromagnetic forces extended into the empty space around the conductor, but did not complete his work involving that proposal. In 1846 Michael Faraday speculated that light was a wave disturbance in a force field".

Between 1861 and 1865, based on the earlier experimental work of Faraday and other scientists, James Clerk Maxwell
James Clerk Maxwell
James Clerk Maxwell of Glenlair was a Scottish physicist and mathematician. His most prominent achievement was formulating classical electromagnetic theory. This united all previously unrelated observations, experiments and equations of electricity, magnetism and optics into a consistent theory...

 developed his theory of electromagnetism, which predicted the existence of electromagnetic waves. In 1873 Maxwell described the theoretical basis of the propagation of electromagnetic waves in his paper to the Royal Society
Royal Society
The Royal Society of London for Improving Natural Knowledge, known simply as the Royal Society, is a learned society for science, and is possibly the oldest such society in existence. Founded in November 1660, it was granted a Royal Charter by King Charles II as the "Royal Society of London"...

, "A Dynamical Theory of the Electromagnetic Field
A Dynamical Theory of the Electromagnetic Field
"A Dynamical Theory of the Electromagnetic Field" is the third of James Clerk Maxwell's papers regarding electromagnetism, published in 1865. It is the paper in which the original set of four Maxwell's equations first appeared...

."

Based on the experimental work of Faraday and other physicists, James Clerk Maxwell
James Clerk Maxwell
James Clerk Maxwell of Glenlair was a Scottish physicist and mathematician. His most prominent achievement was formulating classical electromagnetic theory. This united all previously unrelated observations, experiments and equations of electricity, magnetism and optics into a consistent theory...

 in 1864 developed the theory of electromagnetism
Electromagnetism
Electromagnetism is one of the four fundamental interactions in nature. The other three are the strong interaction, the weak interaction and gravitation...

 that predicted the existence of electromagnetic waves, which include radio waves. This theory united all previously unrelated observations, experiments and equations of electricity, magnetism, and optics into a consistent theory. His set of equations—Maxwell's equations
Maxwell's equations
Maxwell's equations are a set of partial differential equations that, together with the Lorentz force law, form the foundation of classical electrodynamics, classical optics, and electric circuits. These fields in turn underlie modern electrical and communications technologies.Maxwell's equations...

—demonstrated that electricity, magnetism, and light are all manifestations of the same phenomenon, the electromagnetic field
Electromagnetic field
An electromagnetic field is a physical field produced by moving electrically charged objects. It affects the behavior of charged objects in the vicinity of the field. The electromagnetic field extends indefinitely throughout space and describes the electromagnetic interaction...

. Subsequently, all other classic laws or equations of these disciplines were special cases of Maxwell's equations. Maxwell's work in electromagnetism has been called the "second great unification in physics".

Although Maxwell did not transmit or receive radio waves his equations still remain the basis of all radio design. Berend Wilhelm Feddersen
Berend Wilhelm Feddersen
Berend Wilhelm Feddersen was a German physicist.-Biography:Feddersen lived from 1858 as a private scholar in Leipzig. In 1859 he succeeded in experiments with the Leyden jar to prove that every single electric spark discharge composed of oscillations...

 (German physicist) in 1859, as a private scholar in Leipzig
Leipzig
Leipzig Leipzig has always been a trade city, situated during the time of the Holy Roman Empire at the intersection of the Via Regia and Via Imperii, two important trade routes. At one time, Leipzig was one of the major European centres of learning and culture in fields such as music and publishing...

, succeeded in experiments with the Leyden jar to prove that electric spark
Electric spark
An electric spark is a type of electrostatic discharge that occurs when an electric field creates an ionized electrically conductive channel in air producing a brief emission of light and sound. A spark is formed when the electric field strength exceeds the dielectric field strength of air...

s were composed of discharge (damped) oscillations. He realized that they arise from a coil, capacitor and resistor existing electrical circuit oscillations.

Formative "wireless" methods


In April 1872 William Henry Ward
William Henry Ward
William Henry Ward on 30 April 1872 was granted a USA patent for "Improvement for collecting electricity for telegraphing" . He theorized that an "electrical layer in the atmosphere" could carry signals like a telegraph wire, and thus is sometimes listed among supposed inventors of radio.-External...

 received for radio development. However, this patent did not refer to any known scientific theory of electromagnetism and could never have received and transmitted radio waves.

A few months after Ward received his patent, Mahlon Loomis
Mahlon Loomis
Mahlon Loomis was an early wireless telegraph experimenter.-Early history:...

 of West Virginia
West Virginia
West Virginia is a state in the Appalachian and Southeastern regions of the United States, bordered by Virginia to the southeast, Kentucky to the southwest, Ohio to the northwest, Pennsylvania to the northeast and Maryland to the east...

 received for a "wireless telegraph" in July 1872. This claimed to utilize atmospheric electricity
Atmospheric electricity
Atmospheric electricity is the regular diurnal variations of the Earth's atmospheric electromagnetic network . The Earth's surface, the ionosphere, and the atmosphere is known as the global atmospheric electrical circuit...

 to eliminate the overhead wire used by the existing telegraph systems. It did not contain diagrams or specific methods and it did not refer to or incorporate any known scientific theory. It is substantially similar to William Henry Ward
William Henry Ward
William Henry Ward on 30 April 1872 was granted a USA patent for "Improvement for collecting electricity for telegraphing" . He theorized that an "electrical layer in the atmosphere" could carry signals like a telegraph wire, and thus is sometimes listed among supposed inventors of radio.-External...

's patent and could not have transmitted and received radio waves.

Towards the end of 1875, while experimenting with the telegraph, Thomas Edison
Thomas Edison
Thomas Alva Edison was an American inventor and businessman. He developed many devices that greatly influenced life around the world, including the phonograph, the motion picture camera, and a long-lasting, practical electric light bulb. In addition, he created the world’s first industrial...

 noted a phenomenon that he termed "etheric force
Etheric force
Etheric force, a term coined by Thomas Edison to describe a phenomenon that was later to be understood as high frequency electromagnetic waves, effectively, radio...

", announcing it to the press on November 28. He abandoned this research when Elihu Thomson
Elihu Thomson
Elihu Thomson was an American engineer and inventor who was instrumental in the founding of major electrical companies in the United States, the United Kingdom and France.-Early life:...

, among others, ridiculed the idea. The idea was not based on the electromagnetic waves described by Maxwell. In 1885, Edison took out on a system of electrical wireless communication between ships (which later he sold to the Marconi Company
Marconi Company
The Marconi Company Ltd. was founded by Guglielmo Marconi in 1897 as The Wireless Telegraph & Signal Company...

). The patent, however, was based on the mutual-inductively coupled or magnetically coupled communication.

Claims have been made that Murray, Kentucky
Murray, Kentucky
Murray is a city in Calloway County, Kentucky, United States. The population was 17,741 at the 2010 census and has a micropolitan area population of 37,191. It is the 22nd largest city in Kentucky...

 farmer Nathan Stubblefield
Nathan Stubblefield
Nathan B. Stubblefield was an American inventor and Kentucky melon farmer. It has been claimed that Stubblefield invented the radio before either Nikola Tesla or Guglielmo Marconi, but his devices seem to have worked by audio frequency induction or, later, audio frequency earth conduction rather...

 developed radio between 1885 and 1892, before either Tesla or Marconi, but his devices seemed to have worked by induction
Electromagnetic induction
Electromagnetic induction is the production of an electric current across a conductor moving through a magnetic field. It underlies the operation of generators, transformers, induction motors, electric motors, synchronous motors, and solenoids....

 transmission rather than radio transmission
Radio propagation
Radio propagation is the behavior of radio waves when they are transmitted, or propagated from one point on the Earth to another, or into various parts of the atmosphere...

.

In 1878, David E. Hughes
David E. Hughes
David Edward Hughes , was a British scientist and musician. Hughes was co-inventor of the microphone, a harpist and a professor of music.-Biography:...

 noticed that sparks could be heard in a telephone receiver when experimenting with his carbon microphone. He developed this carbon-based detector further and eventually could detect signals over a few hundred yards. He demonstrated his discovery to the Royal Society in 1880, but was told it was merely induction
Electromagnetic induction
Electromagnetic induction is the production of an electric current across a conductor moving through a magnetic field. It underlies the operation of generators, transformers, induction motors, electric motors, synchronous motors, and solenoids....

, and therefore abandoned further research, although there have been later claims that he did, in fact, transmit and receive electromagnetic waves. While Professor Hughes was continuing his investigations in this direction, Hertz's papers were published, and then he thought it too late to bring forward these earlier experiments.

Early radio development




The key invention for the beginning of "wireless transmission of data using the entire frequency spectrum", known as the spark-gap transmitter
Spark-gap transmitter
A spark-gap transmitter is a device for generating radio frequency electromagnetic waves using a spark gap.These devices served as the transmitters for most wireless telegraphy systems for the first three decades of radio and the first demonstrations of practical radio were carried out using them...

, has been attributed to various men. Marconi equipped ships with lifesaving wireless communications and established the first transatlantic radio service. Tesla developed means to reliably produce radio frequency electrical currents, publicly demonstrated the principles of radio, and transmitted long distance signals.

In the late 19th century it was clear to various scientists and experimenters that wireless communication was possible. Various theoretical and experimental innovations led to the development of radio and the communication system we know today. Some early work was done by local effects
Near and far field
The near field and far field and the transition zone are regions of the electromagnetic radiation field that emanates from a transmitting antenna, or as a result of radiation scattering off an object...

 and experiment
Experiment
An experiment is a methodical procedure carried out with the goal of verifying, falsifying, or establishing the validity of a hypothesis. Experiments vary greatly in their goal and scale, but always rely on repeatable procedure and logical analysis of the results...

s of electromagnetic induction
Electromagnetic induction
Electromagnetic induction is the production of an electric current across a conductor moving through a magnetic field. It underlies the operation of generators, transformers, induction motors, electric motors, synchronous motors, and solenoids....

. Many understood that there was nothing similar to the "ethereal
Aether (classical element)
According to ancient and medieval science aether , also spelled æther or ether, is the material that fills the region of the universe above the terrestrial sphere.-Mythological origins:...

 telegraphy"
and telegraphy by induction
Radio-frequency induction
Radio-frequency induction or RF induction is the use of a radio frequency magnetic field to transfer energy by means of electromagnetic induction in the near field...

, the phenomena being wholly distinct. Wireless telegraphy was beginning to take hold and the practice of transmitting messages without wires was being developed. Many people worked on developing the devices and improvements.

Early radio's origin and development of old, or damped wave-coherer, methods began with Joseph Henry. He was the first (1838–42) to produce high frequency electrical oscillations, and to point out and experimentally demonstrate that the discharge of a condenser is under certain conditions oscillatory, or, as he puts it, consists "of a principal discharge in one direction and then several reflex actions backward and forward, each more feeble than the preceding until equilibrium is attained". This view was also later adopted by Helmholz, but the mathematical demonstration of this fact was first given by Lord Kelvin in his paper on "Transient Electric Currents".

In 1870 the German physicist Wilhelm von Bezold
Wilhelm von Bezold
Johann Friedrich Wilhelm von Bezold was a German physicist and meteorologist born in Munich, Kingdom of Bavaria....

 discovered and experimentally demonstrated the fact that the advancing and reflected oscillations produced in conductors by a condenser discharge gave rise to interference phenomena. Professors Elihu Thomson
Elihu Thomson
Elihu Thomson was an American engineer and inventor who was instrumental in the founding of major electrical companies in the United States, the United Kingdom and France.-Early life:...

 and E. J. Houston in 1876 made a number of experiments and observations on high frequency oscillatory discharges. In 1883 G. F. Fitzgerald suggested at a British Association meeting that electromagnetic waves could be generated by the discharge of a condenser, but the suggestion was not followed up, possibly because no means was known for detecting the waves.

Hertz discovered a method of detecting such waves by means of a minute spark-gap and, before March 30, 1888, had concluded his remarkable series of researches in which for the first time electromagnetic waves were actually produced by a spark-gap and radiating conductor and received and detected at a distance by a tuned receiving circuit. Hertz changed the frequency of his radiated waves by altering the inductance or capacity of his radiating conductor or antenna, and reflected and focused the electromagnetic waves, thus demonstrating the correctness of Maxwell's electromagnetic theory of light. After Hertz, Sir William Crookes
William Crookes
Sir William Crookes, OM, FRS was a British chemist and physicist who attended the Royal College of Chemistry, London, and worked on spectroscopy...

 discussed the matter of wireless in some detail. Professor Amos Emerson Dolbear
Amos Dolbear
Amos Emerson Dolbear was an American physicist and inventor. His patents interfered with Guglielmo Marconi's planned activities in the U.S. Dolbear researched electrical spark conversion into sound waves and electrical impulses. He was a professor at University of Kentucky in Lexington from 1868...

 also suggested the same thing.

Hertz


Between 1886 and 1888, Heinrich Rudolf Hertz
Heinrich Rudolf Hertz
Heinrich Rudolf Hertz was a German physicist who clarified and expanded the electromagnetic theory of light that had been put forth by Maxwell...

 studied Maxwell's theory and validated it through experiment. Concerning wireless telegraphy, he demonstrated the transmission and reception of the electromagnetic waves predicted by Maxwell and intentionally transmitted and received radio. Hertz changed the frequency of his radiated waves by altering the inductance or capacity of his radiating conductor or antenna, and reflected and focused the electromagnetic waves, thus demonstrating the correctness of Maxwell's electromagnetic theory of light. Famously, he saw no practical use for his discovery.

In his UHF
Ultra high frequency
Ultra-High Frequency designates the ITU Radio frequency range of electromagnetic waves between 300 MHz and 3 GHz , also known as the decimetre band or decimetre wave as the wavelengths range from one to ten decimetres...

 experiments, he transmitted and received radio waves over short distances and showed that the properties of radio waves were consistent with Maxwell’s electromagnetic theory. He demonstrated that radio radiation (now called electromagnetic radiation) had all the properties of waves, and discovered that the electromagnetic equations could be reformulated into a partial differential equation
Partial differential equation
In mathematics, partial differential equations are a type of differential equation, i.e., a relation involving an unknown function of several independent variables and their partial derivatives with respect to those variables...

 called the wave equation
Wave equation
The wave equation is an important second-order linear partial differential equation for the description of waves – as they occur in physics – such as sound waves, light waves and water waves. It arises in fields like acoustics, electromagnetics, and fluid dynamics...

.





Hertz’s setup for a source and detector of radio waves (then called Hertzian waves in his honor) was the first intentional and unequivocal transmission and reception of radio waves
Radio waves
Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. Radio waves have frequencies from 300 GHz to as low as 3 kHz, and corresponding wavelengths from 1 millimeter to 100 kilometers. Like all other electromagnetic waves,...

 through free space. The first of the papers published ("On Very Rapid Electric Oscillations") gives, generally in the actual order of time, the course of the investigation as far as it was carried out up to the end of the year 1886 and the beginning of 1887.

Hertz, though, did not devise a system for actual general use nor describe the application of the technology and seemed uninterested in the practical importance of his experiments. Asked about the ramifications of his discoveries, Hertz replied, "Nothing, I guess." Hertz also stated, "I do not think that the wireless waves I have discovered will have any practical application." Hertz died in 1894, and the art of radio was left to others to implement into a practical form.

Branly


In 1890, Édouard Branly
Edouard Branly
Édouard Eugène Désiré Branly was a French inventor, physicist and professor at the Institut Catholique de Paris. He is primarily known for his early involvement in wireless telegraphy and his invention of the Branly coherer around 1890.-Biography:The coherer was the first widely used detector for...

 demonstrated what he later called the "radio-conductor," which Lodge in 1893 named the coherer
Coherer
The coherer was a primitive form of radio signal detector used in the first radio receivers during the wireless telegraphy era at the beginning of the twentieth century. Invented around 1890 by French scientist Édouard Branly, it consisted of a tube or capsule containing two electrodes spaced a...

, the first sensitive device for detecting radio waves. Shortly after the experiments of Hertz, Dr. Branly discovered that loose metal filings, which in a normal state have a high electrical resistance, lose this resistance in the presence of electric oscillations and become practically conductors of electricity. This Branly showed by placing metal filings in a glass box or tube, and making them part of an ordinary electric circuit. According to the common explanation, when electric waves are set up in the neighborhood of this circuit, electromotive forces are generated in it which appear to bring the filings more closely together, that is, to cohere, and thus their electrical resistance decreases, from which cause this piece of apparatus was termed by Sir Oliver Lodge a coherer. Hence the receiving instrument, which may be a telegraph relay, that normally would not indicate any sign of current from the small battery, can be operated when electric oscillations are set up. Prof. Branly further found that when the filings had once cohered they retained their low resistance until shaken apart, for instance, by tapping on the tube. The coherer, however, was not sensitive enough to be used reliably as radio developed.

Tesla


In 1891 Nikola Tesla
Nikola Tesla
Nikola Tesla was a Serbian-American inventor, mechanical engineer, and electrical engineer...

 began his research into radio. Around July 1891 he developed various alternator apparatus
Alternator
An alternator is an electromechanical device that converts mechanical energy to electrical energy in the form of alternating current.Most alternators use a rotating magnetic field but linear alternators are occasionally used...

 that produced 15,000 cycles per second
Very low frequency
225px|thumb|right|A VLF receiving antenna at [[Palmer Station]], Antarctica, operated by Stanford UniversityVery low frequency or VLF refers to radio frequencies in the range of 3 kHz to 30 kHz. Since there is not much bandwidth in this band of the radio spectrum, only the very simplest signals...

. In 1892 he delivered a lecture called "Experiments with Alternate Currents of High Potential and High Frequency" before the Institution of Electrical Engineers
Institution of Electrical Engineers
The Institution of Electrical Engineers was a British professional organisation of electronics, electrical, manufacturing, and Information Technology professionals, especially electrical engineers. The I.E.E...

 of London, in which he suggested that messages could be transmitted without wires. He repeated this presentation at the Royal Institution
Royal Institution
The Royal Institution of Great Britain is an organization devoted to scientific education and research, based in London.-Overview:...

 and at the Société Française de Physique in Paris. Tesla realized he gained, by the use of very high frequencies, many advantages in his experiments, such as the possibilities of working with one lead and of doing away with the leading-in wire. In transmitting impulses through conductors, he dealt with high pressure and high flow, in the ordinary interpretation of these terms. Towards the end of the lecture, he proposed that sending over the wire current vibrations of very high frequencies at enormous distance without affecting greatly the character of the vibrations and that telephony could be rendered practicable across the Atlantic. He also proposed transmission through the Earth. Tesla captured the attention of the whole scientific world by his fascinating experiments on high frequency electric currents. He stimulated the scientific imagination of others as well as displayed his own, and created a widespread interest in his brilliant demonstrations. Accordingly there are seven elements in the complete oscillation-producing appliance, which are as follows:
  • The induction coil transformer or source of electromotive force
    Electromotive force
    In physics, electromotive force, emf , or electromotance refers to voltage generated by a battery or by the magnetic force according to Faraday's Law, which states that a time varying magnetic field will induce an electric current.It is important to note that the electromotive "force" is not a...

    .
  • The condenser
    Capacitor
    A capacitor is a passive two-terminal electrical component used to store energy in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors separated by a dielectric ; for example, one common construction consists of metal foils separated...

    .
  • The discharger
    Discharger
    A discharger in electronics is a device or circuit that releases stored energy or electric charge from a battery, capacitor or other source.Discharger types include:* metal probe with insulated handle & ground wire, and sometimes resistor...

     or spark ball
    Spark gap
    A spark gap consists of an arrangement of two conducting electrodes separated by a gap usually filled with a gas such as air, designed to allow an electric spark to pass between the conductors. When the voltage difference between the conductors exceeds the gap's breakdown voltage, a spark forms,...

    s.
  • The arc quenching inductances.
  • The oscillation transformer.
  • The adjustable inductance for varying the period.
  • The controller or key
    Telegraph key
    Telegraph key is a general term for any switching device used primarily to send Morse code. Similar keys are used for all forms of manual telegraphy, such as in electrical telegraph and radio telegraphy.- Types of keys :...

     in the primary circuit of the coil or transformer.

These several elements have each to be considered separately with reference to their best practical forms for various purposes. When the key is closed, and the apparatus in operation, there are trains of intermittent electrical oscillations set up in the circuit, and if the terminals of the secondary circuit of the oscillation transformer are near together, there is high potential high frequency oscillatory sparks passing between them. The above-described apparatus in a typical form is generally called a Tesla apparatus for the production of high frequency electric currents.


"On Light and Other High Frequency Phenomena"


In 1893, at St. Louis, Missouri
St. Louis, Missouri
St. Louis is an independent city on the eastern border of Missouri, United States. With a population of 319,294, it was the 58th-largest U.S. city at the 2010 U.S. Census. The Greater St...

, Tesla gave a public demonstration, "On Light and Other High Frequency Phenomena", of wireless communication. Addressing the Franklin Institute
Franklin Institute
The Franklin Institute is a museum in Philadelphia, Pennsylvania, and one of the oldest centers of science education and development in the United States, dating to 1824. The Institute also houses the Benjamin Franklin National Memorial.-History:On February 5, 1824, Samuel Vaughn Merrick and...

in Philadelphia, he described in detail the principles of early radio communication. The lecture apparatus that Tesla used contained all the elements that were incorporated into radio systems before the development of the "oscillation valve", the early vacuum tube
Vacuum tube
In electronics, a vacuum tube, electron tube , or thermionic valve , reduced to simply "tube" or "valve" in everyday parlance, is a device that relies on the flow of electric current through a vacuum...

. The lecture delivered before the Franklin Institute, at Philadelphia, occurred on February 24, 1893. The variety of Tesla's radio frequency systems were again demonstrated during when he presented to meetings of the National Electric Light Association
National Electric Light Association
The National Electric Light Association was a national United States trade association including the operators of central power generation stations and interested individuals. Founded in 1885 by G. S. Bowen Terry and Charles A. Brown, it represented the interests of various private companies...

, at St. Louis, on March I, 1893. Afterward, the principle of radio communication (sending signals through space to receivers) was publicized widely from Tesla's experiments and demonstrations. On August 25, 1893, Tesla delivered the lecture "Mechanical and Electrical Oscillators", before the International Electrical Congress, in the hall adjoining the Agricultural Building, at the World's Fair, Chicago
World's Columbian Exposition
The World's Columbian Exposition was a World's Fair held in Chicago in 1893 to celebrate the 400th anniversary of Christopher Columbus's arrival in the New World in 1492. Chicago bested New York City; Washington, D.C.; and St...

.

The high-frequency phenomena which Tesla first developed and displayed had scientific rather than practical interest; but Tesla called attention to the fact that by taking the Tesla oscillator, grounding one side of it and connecting the other to an insulated body of large surface, it should be possible to transmit electric oscillations to a great distance, and to communicate intelligence in this way to other oscillators in sympathetic resonance therewith. This was going far toward the invention of radio-telegraphy as known in the early 20th century, as stated by the Electrical World in 1917.

Transmission and radiation of radio frequency energy was a feature exhibited in the experiments by Tesla which he proposed might be used for the telecommunication
Telecommunication
Telecommunication is the transmission of information over significant distances to communicate. In earlier times, telecommunications involved the use of visual signals, such as beacons, smoke signals, semaphore telegraphs, signal flags, and optical heliographs, or audio messages via coded...

 of information
Information
Information in its most restricted technical sense is a message or collection of messages that consists of an ordered sequence of symbols, or it is the meaning that can be interpreted from such a message or collection of messages. Information can be recorded or transmitted. It can be recorded as...

. The Tesla method
Wireless energy transfer
Wireless energy transfer or wireless power is the transmission of electrical energy from a power source to an electrical load without artificial interconnecting conductors. Wireless transmission is useful in cases where interconnecting wires are inconvenient, hazardous, or impossible...

 was mentioned in New York in 1897. In Buffalo, New York, he referred to devised means for transmission of electromotive force
Electromotive force
In physics, electromotive force, emf , or electromotance refers to voltage generated by a battery or by the magnetic force according to Faraday's Law, which states that a time varying magnetic field will induce an electric current.It is important to note that the electromotive "force" is not a...

s, much higher than practical with ordinary apparatus, and the transmission of power from station to station without the employment of any connecting wire. Tesla later, on April 6, 1897, explained his methods of the transformation of electrical energy by oscillatory condenser discharges in his lecture "The stream of Lenard and Roentgen and novel apparatus for their production". He demonstrated his subject by a fine array of improved apparatus, in which a few feet of wire were made as efficient as miles under old systems.


In 1894, T. C. Martin
Thomas Commerford Martin
Thomas Commerford Martin was an American electrical engineer and editor, born in London, England. His father worked with Lord Kelvin and other pioneers of submarine telegraph cables, and Martin spent much time on the cable-laying ship SS Great Eastern. Educated as a theological student, Martin...

 published "The Inventions, Researches and Writings of Nikola Tesla", detailing the work of Tesla in the previous years. Various scientists, inventors, and experimenters began to investigate wireless methods. Telsa's work contained coupled oscillation circuits having capacity and inductance in series. In 1897, Tesla applied for two key United States radio patents, , first radio system patent, and (later subdivided into) , for protection of his interests of the radio arts. Tesla also developed sensitive electromagnetic receivers, that were unlike the less responsive coherers later used by other early experimenters.

Shortly thereafter, he began to develop wireless remote control
Remote control
A remote control is a component of an electronics device, most commonly a television set, used for operating the television device wirelessly from a short line-of-sight distance.The remote control is usually contracted to remote...

 devices. In 1898, he demonstrated a radio controlled boat in Madison Square Garden
Madison Square Garden (1890)
Madison Square Garden was an indoor arena in New York City, the second by that name, and the second to be located at 26th Street and Madison Avenue in Manhattan...

 that allowed secure communication
Secure communication
When two entities are communicating and do not want a third party to listen in, they need to communicate in a way not susceptible to eavesdropping or interception. This is known as communicating in a secure manner or secure communication...

 between transmitter and receiver. Between 1895 and 1897, Tesla received wireless signals transmitted via short distances in his lectures. Between 1897 and the first decade of the 1900s, he transmitted over medium ranges. Tesla had predicted that not only would intelligible signals be transmitted over long distances without wires, but electric power as well. He later published articles, such as
"The True Wireless", and "The Transmission of Electric Energy Without Wires", concerning the World Wireless System research.

de Moura


Roberto Landell de Moura, a Brazilian priest and scientist, went to Rome in 1878 and studied at the South American College
South American College in Rome
The South American College in Rome is one of the Roman Colleges of the Roman Catholic Church, for students from Central and South America.-History:...

 and Pontifical Gregorian University
Pontifical Gregorian University
The Pontifical Gregorian University is a pontifical university located in Rome, Italy.Heir of the Roman College founded by Saint Ignatius of Loyola over 460 years ago, the Gregorian University was the first university founded by the Jesuits...

, where he studied physics and chemistry. He completed his clerical training in Rome, graduating in theology and was ordained priest in 1886. In Rome, he started studying physics and electricity. When he returned to Brazil, he conducted experiments in wireless in Campinas
Campinas
Campinas is a city and municipality located in the coastal interior of the state of São Paulo, Brazil. is the administrative center of the meso-region of the same name, with 3,783,597 inhabitants as of the 2010 Census, consisting of 49 cities....

 and São Paulo
São Paulo
São Paulo is the largest city in Brazil, the largest city in the southern hemisphere and South America, and the world's seventh largest city by population. The metropolis is anchor to the São Paulo metropolitan area, ranked as the second-most populous metropolitan area in the Americas and among...

 (1892–1893). The experiments of de Moura were performed in the presence of the English Vice Consul S. Paul, Percy Parmenter, Charles Lupton
Charles Lupton
Captain Charles Roger Lupton was a World War I flying ace credited with five aerial victories.-References:...

, and other persons of high social position. Upon observing the experiments, Rodriguez Botet, giving news of the trials, said he was not far from the moment of the consecration of Landell as an author of radio discoveries. The wireless telephony is reputed the most important discoveries of Landell. De Moura did later pursue and receive several patents on wireless technology. He would later obtain for a wireless telephone.

Lodge


One of the first investigators to notice and measure stationary waves on wires produced by direct coupling
Direct coupling
In electronics, direct coupling is a way of interconnecting two circuits such that, in addition to transferring the AC signal , the first stage also provides DC bias to the next...

 (resonance
Resonance
In physics, resonance is the tendency of a system to oscillate at a greater amplitude at some frequencies than at others. These are known as the system's resonant frequencies...

) with the coatings of a Leyden jar was Sir Oliver Lodge, entitled "Experiments On The Discharge Of Leyden Jars" (1891). On June, 1, 1894, Oliver Lodge at the Royal Institution lectures, delivered "The Work of Hertz and Some of His Successors". Two years after Tesla's high potential and high frequency lecture and five years after Hertz's signals, Lodge performed transmission on August 14, 1894. This was a year before Marconi's initial experiments. Lodge did this at a meeting of the British Association for the Advancement of Science
British Association for the Advancement of Science
frame|right|"The BA" logoThe British Association for the Advancement of Science or the British Science Association, formerly known as the BA, is a learned society with the object of promoting science, directing general attention to scientific matters, and facilitating interaction between...

 at Oxford University. Also in 1894, Lodge would state that Alexander Muirhead
Alexander Muirhead
Alexander Muirhead, FRS, born in East Saltoun, East Lothian, Scotland was an electrical engineer specialising in wireless telegraphy.-Biography:...

 clearly foresaw the telegraphic importance of the transmission of transverse Hertzian waves. A convenient method of establishing stationary electric waves on wires is one which generally attribute to Ernst Lecher
Ernst Lecher
Ernst Lecher was an Austrian physicist who, from 1909, was head of the First Institute of Physics in Vienna. He is remembered for developing an apparatus— "Lecher lines"—to measure the wavelength and frequency of electromagnetic waves...

, and call the Lecher arrangement
Lecher lines
In electronics, a Lecher line or Lecher wires is a pair of parallel wires or rods that were used to measure the wavelength of radio waves, mainly at UHF and microwave frequencies. They form a short length of balanced transmission line. When attached to a source of radio frequency power such as a...

. As a matter of fact, it originated with Lodge and Hertz, whilst Edouard Sarasin and Lucien de la Rive gave it an improved form.

On that day in August 1894, Lodge demonstrated the reception of Morse code
Morse code
Morse code is a method of transmitting textual information as a series of on-off tones, lights, or clicks that can be directly understood by a skilled listener or observer without special equipment...

 signalling via radio waves using a "coherer
Coherer
The coherer was a primitive form of radio signal detector used in the first radio receivers during the wireless telegraphy era at the beginning of the twentieth century. Invented around 1890 by French scientist Édouard Branly, it consisted of a tube or capsule containing two electrodes spaced a...

". He later improved Branly's coherer by adding a "trembler" which dislodged clumped filings, thus restoring the device's sensitivity. In August 1898 he got , "Electric Telegraphy", that made wireless signals using Ruhmkorff coils or Tesla coil
Tesla coil
A Tesla coil is a type of resonant transformer circuit invented by Nikola Tesla around 1891. It is used to produce high voltage, low current, high frequency alternating current electricity. Tesla coils produce higher current than the other source of high voltage discharges, electrostatic machines...

s for the transmitter and a Branly coherer for the detector. This patent was utilizing the concept of "syntonic" tuning. In 1912 Lodge sold the patent to Marconi.
Lodge 1894 lecture

Lodge's June 1, 1894 lecture before the Royal Institution. described among other things the following:
  1. Filings coherer
  2. Vacuum coherer
  3. Automatic coherer tapper
  4. Metallic focusing wave reflector
  5. Grounded conductor
  6. Coupled system
  7. Method of detection

In this lecture, Lodge stated that in his estimate the apparatus used would respond to signals at a distance of 0.5 mile (0.80467 km).

In 1894 Lodge showed that the Branly coherer could be employed to transmit telegraphic signals, and in order that the filings should not remain "cohered" after the cessation of the electric oscillations, he devised an electro-mechanical "tapper" on the principle of the ordinary "buzzer," or electric door-bell, the hammer of which was caused to tap the glass tube as long as the electric oscillations continued. The filings thus virtually take the place of a key in the ordinary telegraph circuit. In the normal state the key is open; in the presence of electrical oscillations the key is closed. Thus, by opening and closing the key for a longer or shorter period, signals corresponding to dots and dashes may be produced. In other words, by setting up electric oscillations for periods of time corresponding to dots and dashes, messages may be transmitted from the sending station, and if, at the receiving station, a recording instrument (controlled by the coherer), such as the ordinary Morse register, be provided, a record of the message in dots and dashes may be obtained. Dr. Lodge in fact used a tapper operated continuously by clockwork.

In 1894, with the help of the Branly filings tube, Lodge gave a couple of demonstrations, one in June at the Royal Institution
Royal Institution
The Royal Institution of Great Britain is an organization devoted to scientific education and research, based in London.-Overview:...

 at Oxford and one in August at Oxford, to the British Association, using Hertz oscillators for transmitting signals, using a Morse key in connection with the sending coil, and a Thomson marine galvanometer for receiving them—sending the signals from one room to another through walls, and so on. Lodge sent them also across the quadrangle
Quadrangle (architecture)
In architecture, a quadrangle is a space or courtyard, usually rectangular in plan, the sides of which are entirely or mainly occupied by parts of a large building. The word is probably most closely associated with college or university campus architecture, but quadrangles may be found in other...

 of Liverpool College, but he applied very small power and did not try for big distances. At that time Dr. Alexander Muirhead
Alexander Muirhead
Alexander Muirhead, FRS, born in East Saltoun, East Lothian, Scotland was an electrical engineer specialising in wireless telegraphy.-Biography:...

 was struck with its applicability to practical telegraphy, and when in 1896 Sir William Preece told the British Association meeting (as it happened in his laboratory) at Liverpool that an Italian gentleman (at that time unknown)
Guglielmo Marconi
Guglielmo Marconi was an Italian inventor, known as the father of long distance radio transmission and for his development of Marconi's law and a radio telegraph system. Marconi is often credited as the inventor of radio, and indeed he shared the 1909 Nobel Prize in Physics with Karl Ferdinand...

 was interesting the Post Office in a secret box, Lodge knew practically what the box must contain, and immediately afterwards (the same day) he showed to a few friends a Morse tape instrument, very roughly working on that plan. Mr. Marconi and Sir William Preece together interested the whole world in the subject; great power was applied to the sender, and the matter became of financial importance. However, the American Patent Office gave Lodge a telegraphic patent based on his work, as published in 1894, after proof that this book had reached America in or before 1895.

Bose


In November 1894, the Indian physicist, Jagadish Chandra Bose, demonstrated publicly the use of radio waves in Calcutta
Kolkata
Kolkata , formerly known as Calcutta, is the capital of the Indian state of West Bengal. Located on the east bank of the Hooghly River, it was the commercial capital of East India...

, but he was not interested in patenting his work. Bose ignited gunpowder and rang a bell at a distance using electromagnetic waves, proving that communication signals can be sent without using wires. He sent and received radio waves over distance but did not commercially exploit this achievement.

The 1895 public demonstration by Bose in Calcutta was before Marconi's wireless signalling experiment on Salisbury Plain
Salisbury Plain
Salisbury Plain is a chalk plateau in central southern England covering . It is part of the Southern England Chalk Formation and largely lies within the county of Wiltshire, with a little in Hampshire. The plain is famous for its rich archaeology, including Stonehenge, one of England's best known...

 in England in May 1897. Bose demonstrated the ability of the electric rays to travel from the lecture room, and through an intervening room and passage, to a third room 75 feet (22.9 m) distant from the radiator, thus passing through three solid walls on the way, as well as the body of the chairman (who happened to be the Lieutenant-Governor). The receiver at this distance still had energy enough to make a contact which set a bell ringing, discharged a pistol, and exploded a miniature mine. To get this result from his small radiator, Bose set up an apparatus which curiously anticipated the lofty 'antennae' of modern wireless telegraphy— a circular metal plate at the top of a pole, 20 feet (6.1 m) high, being put in connection with the radiator and a similar one with the receiving apparatus.

The form of 'Coherer' devised by Professor Bose, and described by him at the end of his paper 'On a new Electro Polariscope' allowed for the sensibility and range to appear to leave little to be desired at the time. In 1896, the Daily Chronicle
Daily Chronicle
The Daily Chronicle was a British newspaper that was published from 1872 to 1930 when it merged with the Daily News to become the News Chronicle.-History:...

 of England reported on his UHF experiments: "The inventor (J.C. Bose) has transmitted signals to a distance of nearly a mile and herein lies the first and obvious and exceedingly valuable application of this new theoretical marvel."

After Bose's Friday Evening Discourses at the Royal Institution
Royal Institution
The Royal Institution of Great Britain is an organization devoted to scientific education and research, based in London.-Overview:...

, The Electric Engineer expressed 'surprise that no secret was at any time made as to its construction, so that it has been open to all the world to adopt it for practical and possibly money-making purposes.'
Bose was sometimes, and not unnaturally, criticised as unpractical for making no profit from his inventions.

In 1899, Bose announced the development of an "iron-mercury-iron coherer
Coherer
The coherer was a primitive form of radio signal detector used in the first radio receivers during the wireless telegraphy era at the beginning of the twentieth century. Invented around 1890 by French scientist Édouard Branly, it consisted of a tube or capsule containing two electrodes spaced a...

 with telephone
Telephone
The telephone , colloquially referred to as a phone, is a telecommunications device that transmits and receives sounds, usually the human voice. Telephones are a point-to-point communication system whose most basic function is to allow two people separated by large distances to talk to each other...

 detector
" in a paper presented at the Royal Society
Royal Society
The Royal Society of London for Improving Natural Knowledge, known simply as the Royal Society, is a learned society for science, and is possibly the oldest such society in existence. Founded in November 1660, it was granted a Royal Charter by King Charles II as the "Royal Society of London"...

, London. Later he received , "Detector for electrical disturbances" (1904), for a specific electromagnetic receiver. Bose would continue research and made other contributuions to the development of radio.

Rutherford


The New Zealander Ernest Rutherford, 1st Baron Rutherford of Nelson contributed to the development of radio. In 1895 he was awarded an Exhibition of 1851 Science Research Scholarship to Cambridge. He arrived in England with a reputation as an innovator and inventor, and distinguished himself in several fields, initially by working out the electrical properties of solids and then using wireless waves as a method of signalling. Rutherford was encouraged in his work by Sir Robert Ball, who had been scientific adviser to the body maintaining lighthouse
Lighthouse
A lighthouse is a tower, building, or other type of structure designed to emit light from a system of lamps and lenses or, in older times, from a fire, and used as an aid to navigation for maritime pilots at sea or on inland waterways....

s on the Irish coast; he wished to solve the difficult problem of a ship's inability to detect a lighthouse in fog. Sensing fame and fortune, Rutherford increased the sensitivity of his apparatus until he could detect electromagnetic waves via his electromagnetic receiver over a distance of several hundred meters. The hysteresis magnetic detector invented by Rutherford, and described by him in 1897, was used to determine the characteristics of electromagnetic waves, the ends of the little solenoid of the detector being attached to the mercury cups of the slider. The development, though, of wireless technology was left for others, as Rutherford continued purely scientific research. J. J. Thomson
J. J. Thomson
Sir Joseph John "J. J." Thomson, OM, FRS was a British physicist and Nobel laureate. He is credited for the discovery of the electron and of isotopes, and the invention of the mass spectrometer...

 realized that Rutherford was a researcher of ability and invited him to join in a study of the electrical conduction of gases.

Braun


Ferdinand Braun's major contributions were the introduction of a closed tuned circuit in the generating part of the transmitter, and its separation from the radiating part (the antenna) by means of inductive coupling, and later on the usage of crystals for receiving purposes. Braun experimented at first at the University of Strassbourg. Braun had written extensively on wireless subjects and was well known through his many contributions to the Electrician and other scientific journals. In 1899, he would apply for the patents, Electro telegraphy by means of condensers and induction colls and Wireless electro transmission of signals over surfaces.

Pioneers working on wireless devices eventually came to a limit of distance they could cover. Connecting the antenna directly to the spark gap produced only a heavily damped pulse train. There were only a few cycles before oscillations ceased. Braun's circuit afforded a much longer sustained oscillation because the energy encountered less loss swinging between coil and Leyden Jars. Also, by means of inductive antenna coupling the radiator was matched to the generator.

In spring 1899 Braun, accompanied by his colleagues Cantor and Zenneck, went to Cuxhaven to continue their experiments at the North Sea. On February 6, 1899, he would apply for the United States Patent, . Not before long he bridged a distance of 42 km to the city of Mutzing. On 24 September 1900 radio telegraphy signals were exchanged regularly with the island of Heligoland over a distance of 62 km. Lightvessels in the river Elbe and a coast station at Cuxhaven commenced a regular radio telegraph service. On August 6, 1901, he would apply for .

By 1904, the closed circuit system of wireless telegraphy, connected with the name of Braun, was well known and generally adopted in principle. The results of Braun's experiments, published in the Electrician, possess interest, apart from the method employed. Braun showed how the problem could be satisfactorily and economically solved. The closed circuit oscillator has the advantage, as was known, of being able to draw upon the kinetic energy in the oscillator circuit, and thus, owing to the fact that such a circuit can be given a much greater capacity than can be obtained with a radiating aerial alone, much more energy can be stored up and radiated by its employment. The emission is also prolonged, both results tending towards the attainment of the much desired train of undamped waves. The energy available, though greater than with the open system, was still inconsiderable unless very high potentials, with the attendant drawbacks, were used. Braun avoided the use of extremely high potentials for charging the gap and also makes use of a less wasteful gap by sub-dividing it. The chief point in his new arrangement, however, is not the sub-division of the gap merely but their arrangement, by which they are charged in parallel, at low voltages, and discharge in series. The Nobel Prize
Nobel Prize
The Nobel Prizes are annual international awards bestowed by Scandinavian committees in recognition of cultural and scientific advances. The will of the Swedish chemist Alfred Nobel, the inventor of dynamite, established the prizes in 1895...

 awarded to Braun in 1909 depicts this design.

Later radio development




Popov


During the Chicago World's Columbian Exhibition and the Third International Electrical Congress, Alexander Stepanovich Popov of Kronstadt, Russia
Kronstadt
Kronstadt , also spelled Kronshtadt, Cronstadt |crown]]" and Stadt for "city"); is a municipal town in Kronshtadtsky District of the federal city of St. Petersburg, Russia, located on Kotlin Island, west of Saint Petersburg proper near the head of the Gulf of Finland. Population: It is also...

 was a representative of the Russian Torpedo School. Afterward, he worked on his wireless designs. Popov conducted experiments along the lines of Hertz's research. In 1894-95 he built his first radio receiver, an improved version of coherer
Coherer
The coherer was a primitive form of radio signal detector used in the first radio receivers during the wireless telegraphy era at the beginning of the twentieth century. Invented around 1890 by French scientist Édouard Branly, it consisted of a tube or capsule containing two electrodes spaced a...

-based design by Oliver Lodge. In 1895, he built a coherer
Coherer
The coherer was a primitive form of radio signal detector used in the first radio receivers during the wireless telegraphy era at the beginning of the twentieth century. Invented around 1890 by French scientist Édouard Branly, it consisted of a tube or capsule containing two electrodes spaced a...

. Popov constructed a filings coherer, one form of which was used in some surveying experiments by the Russian government. He used early in 1895, the coherer auto-tapping mechanism, and substituted for the galvanometer an ordinary telegraphic relay. He operated this apparatus at a distance by means of a large radiator. One terminal of his coherer was connected to a conductor fastened to a mast about 30 ft. high on the top of the Institute building and the other terminal of the coherer was grounded.

Popov presented his radio receiver to the Russian Physical and Chemical Society on May 7, 1895 — the day has been celebrated in the Russian Federation as "Radio Day
Radio Day
Radio Day , Communications Workers' Day or Radio and Television Day is a commemoration of the development of radio in Russia...

". On this day, Popov performed a public demonstration of transmission and reception of radio waves used for communication at the Russian Physical and Chemical Society, using his coherer. The paper on his findings was published the same year (December 15, 1895). Popov had recorded, at the end of 1895, that he was hoping for distant signaling with radio waves. He did not apply for a patent for this invention. Popov's early experiments were transmissions of only 600 yards (548.6 m). Popov was the first to develop a practical communication system based on the coherer, and is usually considered by the Russians to have been the inventor of radio.

In 1895-96 Popov and others utilized the coherer to show the existence of atmospheric electricity, using for the purpose a vertical wire attached to the coherer. On March 24, 1896, Popov demonstrated in public the transmission of radio waves, between different campus buildings, to the Saint Petersburg
Saint Petersburg
Saint Petersburg is a city and a federal subject of Russia located on the Neva River at the head of the Gulf of Finland on the Baltic Sea...

 Physical Society. (This was before the public demonstration of the Marconi system around September 1896.) Per other accounts, however, Popov achieved these results only in December 1897—that is, after publication of Marconi's patent. In 1898 his signal was received 6 miles (9.7 km) away, and in 1899 130 miles (209.2 km) away.

His receiver proved to be able to sense lightning strikes at distances of up to 30 km, thus functioning as a lightning detector
Lightning detector
A lightning detector is a device that detects lightning produced by thunderstorms. There are three primary types of detectors: ground-based systems using multiple antennas, mobile systems using a direction and a sense antenna in the same location , and space-based systems.The device was invented in...

. In late 1895, Popov built a version of the receiver that was capable of automatically recording lightning strikes on paper rolls. Popov's system was eventually extended to function as a wireless telegraph, with a Morse key attached to the transmitter. There's some dispute regarding the first public test of this design. It is frequently stated that Popov used his radio to send a Morse code message over a distance of 250 m in 26 March 1896 (three months before Marconi's patent was filed). However, contemporary confirmations of this transmission are lacking. It is more likely that said experiment took place in December 1897.

In 1900, Popov stated at the Congress of Russian Electrical Engineers that, "the emission and reception of signals by Marconi by means of electric oscillations was nothing new, as in America Nikola Tesla
Nikola Tesla
Nikola Tesla was a Serbian-American inventor, mechanical engineer, and electrical engineer...

 did the same experiments in 1893
." Also in 1900, a radio station was established under Popov's instructions on Hogland
Hogland
Gogland or Hogland is an island in the Gulf of Finland of the Baltic Sea, located some 180 km west of Saint Petersburg and 35 km away from the coast of Finland . The island is a part of the Leningrad Oblast, Russia. The area of Hogland Island is approximately...

 island (Suursaari) to provide two-way communication by wireless telegraphy between the Russian naval base and the crew of the battleship General-Admiral Apraksin. By February 5 messages were being received reliably. The wireless messages were relayed to Hogland Island by a station some 25 miles (40.2 km) away at Kymi (nowadays Kotka
Kotka
Kotka is a town and municipality of Finland. Its former name is Rochensalm.Kotka is located on the coast of the Gulf of Finland at the mouth of Kymi River and it is part of the Kymenlaakso region in southern Finland. The municipality has a population of and covers an area of of which is water....

) on the Finnish
Grand Duchy of Finland
The Grand Duchy of Finland was the predecessor state of modern Finland. It existed 1809–1917 as part of the Russian Empire and was ruled by the Russian czar as Grand Prince.- History :...

 coast. Later Popov experimented with ship-to-shore communication. Popov died in 1905 and his claim was not pressed by the Russian government until 1945.

Baviera


In May–June 1899, Julio Cervera Baviera
Julio Cervera Baviera
Julio Cervera Baviera was a Spanish engineer, pioneer in the development of radio, educator, explorer, and military man. He also authored various scientific and geographic books and articles.-Education:...

 worked to develop his own system. After visiting Marconi’s radiotelegraphic installations on the English Channel, he began collaborating with Marconi on resolving the problem of a wireless communication system, obtaining some patents by the end of 1899. Cervera, who worked with Marconi and his assistant, George S. Kemp, in 1899, resolved the issues with their wireless telegraph. He obtained his first patents prior to the end of that year.

Marconi


Guglielmo Marconi
Guglielmo Marconi
Guglielmo Marconi was an Italian inventor, known as the father of long distance radio transmission and for his development of Marconi's law and a radio telegraph system. Marconi is often credited as the inventor of radio, and indeed he shared the 1909 Nobel Prize in Physics with Karl Ferdinand...

 studied at the Leghorn Technical School, and acquainted himself with the published writings of Professor Augusto Righi
Augusto Righi
Augusto Righi was an Italian physicist and a pioneer in the study of electromagnetism. He was born and died in Bologna.His early research, conducted in Bologna between 1872 and 1880, was primarily in electrostatics...

 of the University of Bologna
University of Bologna
The Alma Mater Studiorum - University of Bologna is the oldest continually operating university in the world, the word 'universitas' being first used by this institution at its foundation. The true date of its founding is uncertain, but believed by most accounts to have been 1088...

. In 1894, Sir William Preece deliver a paper to the Royal Institution in London on electric signalling without wires. In 1894 at the Royal Institution lectures, Lodge delivers "The Work of Hertz and Some of His Successors". Marconi is said to have read, while on vacation in 1894, about the experiments that Hertz did in the 1880s. Marconi also read about Tesla's work. It was at this time that Marconi began to understand that radio waves could be used for wireless communications. Marconi's early apparatus was a development of Hertz’s laboratory apparatus into a system designed for communications purposes. At first Marconi used a transmitter to ring a bell in a receiver in his attic laboratory. He then moved his experiments out-of-doors on the family estate near Bologna, Italy, to communicate further. He replaced Hertz’s vertical dipole with a vertical wire topped by a metal sheet, with an opposing terminal connected to the ground. On the receiver side, Marconi replaced the spark gap with a metal powder coherer, a detector developed by Edouard Branly
Edouard Branly
Édouard Eugène Désiré Branly was a French inventor, physicist and professor at the Institut Catholique de Paris. He is primarily known for his early involvement in wireless telegraphy and his invention of the Branly coherer around 1890.-Biography:The coherer was the first widely used detector for...

 and other experimenters. Marconi transmitted radio signals for about 1 miles (1.6 km) at the end of 1895.

By 1896, Marconi introduced to the public a device in London
London
London is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...

, asserting it was his invention. Despite Marconi's statements to the contrary, though, the apparatus resembles Tesla's descriptions in his research, demonstrations and patents. Marconi's later practical four-tuned system was pre-dated by N. Tesla, Oliver Lodge, and J. S. Stone. He filed a patent on his earliest system with the British Patent Office on June 2, 1896.

Marconi was awarded a patent for radio with British patent No. 12,039, Improvements in Transmitting Electrical Impulses and Signals and in Apparatus There-for. The complete specification was filed March 2, 1897. This was Marconi's initial patent for the radio, though it used various earlier techniques of various other experimenters (primarily Tesla) and resembled the instrument demonstrated by others (including Popov). During this time spark-gap wireless telegraphy was widely researched. In July, 1896, Marconi got his invention and new method of telegraphy to the attention of Preece, then engineer-in-chief to the British Government Telegraph Service, who had for the previous twelve years interested himself in the development of wireless telegraphy by the inductive-conductive method. On June 4, 1897, he delievers "Signalling through Space without Wires". Preece devoted considerable time to exhibiting and explaining the Marconi apparatus at the Royal Institution
Royal Institution
The Royal Institution of Great Britain is an organization devoted to scientific education and research, based in London.-Overview:...

 in London, stating that Marconi invented a new relay which had high sensitiveness and delicacy.
In 1896, Bose went to London on a lecture tour and met Marconi, who was conducting wireless experiments for the British post office. The Marconi Company Ltd. was founded by Marconi in 1897, known as the Wireless Telegraph Trading Signal Company. Also in 1897, Marconi established the radio station at Niton, Isle of Wight
Niton, Isle of Wight
Niton is a village on the Isle of Wight, near Ventnor with a thriving population of 1142, supporting two pubs, several churches,a pottery workshop/shop, a pharmacy and 3 local shops including a post office...

, England. Marconi's wireless telegraphy was inspected by the Post Office Telegraph authorities; they made a series of experiments with Marconi's system of telegraphy without connecting wires, in the Bristol Channel
Bristol Channel
The Bristol Channel is a major inlet in the island of Great Britain, separating South Wales from Devon and Somerset in South West England. It extends from the lower estuary of the River Severn to the North Atlantic Ocean...

. The October wireless signals of 1897 were sent from Salisbury Plain
Salisbury Plain
Salisbury Plain is a chalk plateau in central southern England covering . It is part of the Southern England Chalk Formation and largely lies within the county of Wiltshire, with a little in Hampshire. The plain is famous for its rich archaeology, including Stonehenge, one of England's best known...

 to Bath, a distance of 34 miles (54.7 km). Marconi's reputation is largely based on the making of his law
Marconi's law
Marconi's law is the relation between height of antennae and maximum signalling distance. Guglielmo Marconi enunciated at one time an empirical law that, for simple vertical sending and receiving antennae of equal height, the maximum working telegraphic distance varied as the square of the height...

 (1897), and other accomplishments in radio communications and commercializing a practical system.

Other experimental stations were established at Lavernock Point, near Penarth
Penarth
Penarth is a town and seaside resort in the Vale of Glamorgan , Wales, 5.2 miles south west from the city centre of the Welsh capital city of Cardiff and lying on the north shore of the Severn Estuary at the southern end of Cardiff Bay...

; on the Flat Holmes, an island in mid-channel, and at Brean Down
Brean Down
Brean Down is a promontory off the coast of Somerset standing high and extending into the Bristol Channel at the eastern end of Bridgwater Bay between Weston-super-Mare and Burnham-on-Sea....

, a promontory
Promontory
Promontory may refer to:*Promontory, a prominent mass of land which overlooks lower lying land or a body of water*Promontory, Utah, the location where the United States first Transcontinental Railroad was completed...

 on the Somerset
Somerset
The ceremonial and non-metropolitan county of Somerset in South West England borders Bristol and Gloucestershire to the north, Wiltshire to the east, Dorset to the south-east, and Devon to the south-west. It is partly bounded to the north and west by the Bristol Channel and the estuary of the...

 side. Signals were obtained between the first and last-named points, a distance of, approximately, 8 miles (12.9 km). The receiving instrument used was a Morse inkwriter of the Post Office pattern. In 1898, Marconi opened a radio factory in Hall Street, Chelmsford, England, employing around 50 people. In 1899, Marconi announced his invention of the "iron-mercury-iron coherer with telephone detector" in a paper presented at Royal Society, London.

In May, 1898, communication was established for the Corporation of Lloyds
Lloyd's of London
Lloyd's, also known as Lloyd's of London, is a British insurance and reinsurance market. It serves as a partially mutualised marketplace where multiple financial backers, underwriters, or members, whether individuals or corporations, come together to pool and spread risk...

 between Ballycastle
Ballycastle, County Antrim
Ballycastle is a small town in County Antrim in Northern Ireland. Its population was 5,089 people in the 2001 Census. It is the seat and main settlement of Moyle District Council....

 and the Lighthouse
Lighthouse
A lighthouse is a tower, building, or other type of structure designed to emit light from a system of lamps and lenses or, in older times, from a fire, and used as an aid to navigation for maritime pilots at sea or on inland waterways....

 on Rathlin Island
Rathlin Island
Rathlin Island is an island off the coast of County Antrim, and is the northernmost point of Northern Ireland. Rathlin is the only inhabited offshore island in Northern Ireland, with a rising population of now just over 100 people, and is the most northerly inhabited island off the Irish coast...

 in the North of Ireland. In July, 1898, the Marconi telegraphy was employed to report the results of yacht races at the Kingston Regatta
Kingston Regatta
Kingston Regatta is a rowing regatta, on the River Thames in England which takes place at Kingston upon Thames, Surrey on the reach above Teddington Lock....

 for the Dublin Express
Daily Express (Dublin)
The Daily Express of Dublin was an Irish newspaper published from 1851 until June 1921, and then continued for registration purposes until 1960.It was a unionist newspaper. From 1917, its title was the Daily Express and Irish Daily Mail...

 newspaper. A set of instruments were fitted up in a room at Kingstown, and another on board a steamer, the Flying Huntress. The aerial conductor on shore was a strip of wire netting attached to a mast 40 feet (12.2 m) high, and several hundred messages were sent and correctly received during the progress of the races.

At this time His Majesty King Edward VII, then Prince of Wales
Prince of Wales
Prince of Wales is a title traditionally granted to the heir apparent to the reigning monarch of the United Kingdom of Great Britain and Northern Ireland and the 15 other independent Commonwealth realms...

, had the misfortune to injure his knee, and was confined on board the royal yacht Osltorm in Cowes Bay.
Marconi fitted up his apparatus on board the royal yacht by request, and also at Osborne House
Osborne House
Osborne House is a former royal residence in East Cowes, Isle of Wight, UK. The house was built between 1845 and 1851 for Queen Victoria and Prince Albert as a summer home and rural retreat....

, Isle of Wight, and kept up wireless communication for three weeks between these stations. The distances covered were small; but as the yacht moved about, on some occasions high hills were interposed, so that the aerial wires were overtopped by hundreds of feet, yet this was no obstacle to communication. These demonstrations led the Corporation of Trinity House to afford an opportunity for testing the system in practice between the South Foreland Lighthouse
South Foreland Lighthouse
South Foreland Lighthouse is a Victorian lighthouse on the South Foreland in St. Margaret's Bay, Dover, Kent, England, used to warn ships approaching the nearby Goodwin Sands. It went out of service in 1988 and is currently owned by the National Trust...

, near Dover, and the East Goodwin Lightship, on the Goodwin Sands
Goodwin Sands
The Goodwin Sands is a 10-mile-long sand bank in the English Channel, lying six miles east off Deal in Kent, England. The Brake Bank lying shorewards is part of the same geological unit. As the shoals lie close to major shipping channels, more than 2,000 ships are believed to have been wrecked...

. This installation was set in operation on December 24, 1898, and proved to be of value. It was shown that when once the apparatus was set up it could be worked by ordinary seamen with very little training.

At the end of 1898 electric wave telegraphy established by Marconi had demonstrated its utility, especially for communication between ship and ship and ship and shore. Electric wave telegraphy had the advantages as follows:
  • Transmission worked as well by night as by day, and in bad weather, fogs, or storms, as well as in fair weather; provided that the proper insulation of the aerial wire or elevated conductor was maintained.
  • In certain electrical conditions of the atmosphere, and during thunderstorms, some difficulty was usually found in working, owing to the atmospheric discharges affecting the sensitive tube, and therefore making stray marks on the Morse tape of the printer, but seldom sufficient to interrupt communication altogether.
  • The interposition of high hills, trees, or the curvature of the earth did not prevent communication, though slightly affecting the power required. It worked particularly well over sea surface, and between ships and shore stations.
  • The apparatus could be set up and handled by any ordinary telegraphist, and the record was made on paper strip in the usual Morse code.
  • Transmission easily covered distances far beyond those feasible or attained by other systems of wireless telegraphy.
  • Lastly, the apparatus required was by no means costly, and, with the exception of the mast required for upholding the aerial wire, it occupied but little space, and was particularly adapted for use on board ship.


The Haven Hotel
Haven Hotel
The Haven Hotel is an AA four star hotel in Sandbanks, near Poole, Dorset on the south coast of England.-History:The first hotel built on this location was the North Haven Inn in 1838. The Inn was demolished and replaced with the present Haven Hotel in 1887...

 station and Wireless Telegraph Mast was where much of Marconi's research work on wireless telegraphy was carried out after 1898. In 1899, he transmitted messages across the English Channel
English Channel
The English Channel , often referred to simply as the Channel, is an arm of the Atlantic Ocean that separates southern England from northern France, and joins the North Sea to the Atlantic. It is about long and varies in width from at its widest to in the Strait of Dover...

. Also in 1899, Marconi delivered "Wireless Telegraphy" to the Institution of Electrical Engineers
Institution of Electrical Engineers
The Institution of Electrical Engineers was a British professional organisation of electronics, electrical, manufacturing, and Information Technology professionals, especially electrical engineers. The I.E.E...

. In addition, in 1899, W. H. Preece delivers "Aetheric Telegraphy", stating that the experimental stage in wireless telegraphy had been passed in 1894 and inventors were then entering the commercial stage. Preece, continuing in the lecture, details the work of Marconi and other British inventors. In October, 1899, the progress of the yachts in the international race
America's Cup
The America’s Cup is a trophy awarded to the winner of the America's Cup match races between two yachts. One yacht, known as the defender, represents the yacht club that currently holds the America's Cup and the second yacht, known as the challenger, represents the yacht club that is challenging...

 between the Columbia and Shamrock was successfully reported by aerial telegraphy, as many as 4,000 words having been (as is said) despatched from the two ship stations to the shore stations. Immediately afterward the apparatus was placed by request at the service of the United States Navy Board, and some highly interesting experiments followed under Marconi's personal supervision. The Marconi Company was renamed Marconi's Wireless Telegraph Company in 1900.


In 1901, Marconi claimed to have received daytime transatlantic radio frequency signals at a wavelength of 366 metres
Medium frequency
Medium frequency refers to radio frequencies in the range of 300 kHz to 3 MHz. Part of this band is the medium wave AM broadcast band. The MF band is also known as the hectometer band or hectometer wave as the wavelengths range from ten down to one hectometers...

 (820 kHz). Marconi established a wireless transmitting station at Marconi House, Rosslare Strand, Co. Wexford in 1901 to act as a link between Poldhu in Cornwall and Clifden in Co. Galway. His announcement on 12 December 1901, using a 152.4 metres (500 ft) kite-supported antenna for reception, stated a the message was received at Signal Hill in St John's
St. John's, Newfoundland and Labrador
St. John's is the capital and largest city in Newfoundland and Labrador, and is the oldest English-founded city in North America. It is located on the eastern tip of the Avalon Peninsula on the island of Newfoundland. With a population of 192,326 as of July 1, 2010, the St...

, Newfoundland
Newfoundland and Labrador
Newfoundland and Labrador is the easternmost province of Canada. Situated in the country's Atlantic region, it incorporates the island of Newfoundland and mainland Labrador with a combined area of . As of April 2011, the province's estimated population is 508,400...

 (now part of Canada) via signals transmitted by the company's new high-power station at Poldhu
Poldhu
Poldhu is a small area in south Cornwall, England, UK, situated on the Lizard Peninsula; it comprises Poldhu Point and Poldhu Cove. It lies on the coast west of Goonhilly Downs, with Mullion to the south and Porthleven to the north...

, Cornwall
Cornwall
Cornwall is a unitary authority and ceremonial county of England, within the United Kingdom. It is bordered to the north and west by the Celtic Sea, to the south by the English Channel, and to the east by the county of Devon, over the River Tamar. Cornwall has a population of , and covers an area of...

. The message received was the Morse letter 'S' - three dots. Bradford has recently contested this, however, based on theoretical work as well as a reenactment of the experiment; it is possible that what was heard was only random atmospheric noise, which was mistaken for a signal, or that Marconi may have heard a shortwave
Shortwave
Shortwave radio refers to the upper MF and all of the HF portion of the radio spectrum, between 1,800–30,000 kHz. Shortwave radio received its name because the wavelengths in this band are shorter than 200 m which marked the original upper limit of the medium frequency band first used...

 harmonic
Harmonic
A harmonic of a wave is a component frequency of the signal that is an integer multiple of the fundamental frequency, i.e. if the fundamental frequency is f, the harmonics have frequencies 2f, 3f, 4f, . . . etc. The harmonics have the property that they are all periodic at the fundamental...

 of the signal. The distance between the two points was about 3500 kilometres (2,174.8 mi).

The Poldhu
Poldhu
Poldhu is a small area in south Cornwall, England, UK, situated on the Lizard Peninsula; it comprises Poldhu Point and Poldhu Cove. It lies on the coast west of Goonhilly Downs, with Mullion to the south and Porthleven to the north...

 to Newfoundland transmission claim has been criticized. There are various science historians, such as Belrose and Bradford, who have cast doubt that the Atlantic was bridged in 1901, but other science historians have taken the position that this was the first transatlantic radio transmission. Critics have claimed that it is more likely that Marconi received stray atmospheric noise from atmospheric electricity
Atmospheric electricity
Atmospheric electricity is the regular diurnal variations of the Earth's atmospheric electromagnetic network . The Earth's surface, the ionosphere, and the atmosphere is known as the global atmospheric electrical circuit...

 in this experiment. The transmitting station in Poldhu, Cornwall used a spark-gap transmitter that could produce a signal in the medium frequency range and with high power levels.

Marconi transmitted from England to Canada and the United States. In this period, a particular electromagnetic receiver, called the Marconi magnetic detector or hysteresis magnetic detector, was developed further by Marconi and was successfully used in his early transatlantic work (1902) and in many of the smaller stations for a number of years. In 1902, a Marconi station
Marconi Station
The Marconi Wireless Corporation operated numerous pioneering radio stations in Canada, Ireland, Newfoundland, the United States, the United Kingdom and a number of other locations around the world.-Australia:...

 was established in the village of Crookhaven
Crookhaven
Crookhaven is a village in County Cork, Ireland, on the most southwestern tip of Ireland. A winter population of about forty swells in the summer to about four hundred with the occupants of the many holiday homes arriving.-History:...

, County Cork
County Cork
County Cork is a county in Ireland. It is located in the South-West Region and is also part of the province of Munster. It is named after the city of Cork . Cork County Council is the local authority for the county...

, Ireland
Ireland
Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...

 to provide marine radio communications to ships arriving from the Americas. A ship's master could contact shipping line agents ashore to enquire which port was to receive their cargo without the need to come ashore at what was the first port of landfall. Ireland was also, due to its western location, to play a key role in early efforts to send trans-Atlantic messages. Marconi transmitted from his station in Glace Bay, Nova Scotia, Canada across the Atlantic, and on 18 January 1903 a Marconi station sent a message of greetings from Theodore Roosevelt
Theodore Roosevelt
Theodore "Teddy" Roosevelt was the 26th President of the United States . He is noted for his exuberant personality, range of interests and achievements, and his leadership of the Progressive Movement, as well as his "cowboy" persona and robust masculinity...

, the President of the United States, to the King of the United Kingdom, marking the first transatlantic radio transmission originating in the United States

In 1904, Marconi opened the ocean daily newspaper, the Cunard Daily Bulletin, on the R.M.S.
Royal Mail Ship
Royal Mail Ship , usually seen in its abbreviated form RMS, a designation which dates back to 1840, is the ship prefix used for seagoing vessels that carry mail under contract by Royal Mail...

 "Campania
RMS Campania
RMS Campania was a British ocean liner owned by the Cunard Steamship Line Shipping Company, built by Fairfield Shipbuilding and Engineering Company of Govan, Scotland, and launched on Thursday, 8 September 1891....

." At the start, the passing events were printed in a little pamphlet of four pages called the Cunard Bulletin. The title would read Cunard Daily Bulletin, with subheads for "Marconigrams Direct to the Ship." All the passenger ships of the Cunard Company are fitted with Marconi's system of wireless telegraphy, by means of which constant communication was kept up, either with other ships or with land stations on the eastern or western hemisphere. The RMS Lucania
RMS Lucania
RMS Lucania was a British ocean liner owned by the Cunard Steamship Line Shipping Company, built by Fairfield Shipbuilding and Engineering Company of Govan, Scotland, and launched on Thursday, 2 February 1893....

, Oct., 1903, with Marconi on board, was the first vessel to hold communication with both sides of the Atlantic. The Cunard Daily Bulletin, a thirty-two page illustrated paper published on board these boats, recorded news received by wireless telegraphy, and is first ocean newspaper. In August, 1903, in agreement was made with the British Government by which the Cunard Co. were to build two steamers, to be, with all other Cunard ships, at the disposal of the British Admiralty for hire or purchase whenever they may be required, the Government lending the company £2,600,000 to build the ships and granting them a subsidy £150,000 a year. One was the RMS Lusitania
RMS Lusitania
RMS Lusitania was a British ocean liner designed by Leonard Peskett and built by John Brown and Company of Clydebank, Scotland. The ship entered passenger service with the Cunard Line on 26 August 1907 and continued on the line's heavily-traveled passenger service between Liverpool, England and New...

 and the RMS Mauritania
RMS Mauretania (1906)
RMS Mauretania was an ocean liner designed by Leonard Peskett and built by Swan, Hunter & Wigham Richardson at Wallsend, Tyne and Wear for the British Cunard Line, and launched on 20 September 1906. At the time, she was the largest and fastest ship in the world. Mauretania became a favourite among...

.

In June and July 1923, Marconi's shortwave
Shortwave
Shortwave radio refers to the upper MF and all of the HF portion of the radio spectrum, between 1,800–30,000 kHz. Shortwave radio received its name because the wavelengths in this band are shorter than 200 m which marked the original upper limit of the medium frequency band first used...

 transmissions were completed during nights on 97 meters from Poldhu Wireless Station
Poldhu
Poldhu is a small area in south Cornwall, England, UK, situated on the Lizard Peninsula; it comprises Poldhu Point and Poldhu Cove. It lies on the coast west of Goonhilly Downs, with Mullion to the south and Porthleven to the north...

, Cornwall
Cornwall
Cornwall is a unitary authority and ceremonial county of England, within the United Kingdom. It is bordered to the north and west by the Celtic Sea, to the south by the English Channel, and to the east by the county of Devon, over the River Tamar. Cornwall has a population of , and covers an area of...

, to his yacht Elettra in the Cape Verde Islands
Cape Verde
The Republic of Cape Verde is an island country, spanning an archipelago of 10 islands located in the central Atlantic Ocean, 570 kilometres off the coast of Western Africa...

. In September 1924, Marconi transmitted during daytime and nighttime on 32 meters from Poldhu to his yacht in Beirut
Beirut
Beirut is the capital and largest city of Lebanon, with a population ranging from 1 million to more than 2 million . Located on a peninsula at the midpoint of Lebanon's Mediterranean coastline, it serves as the country's largest and main seaport, and also forms the Beirut Metropolitan...

. Marconi, in July 1924, entered into contracts with the British General Post Office (GPO) to install telegraphy circuits from London to Australia, India, South Africa and Canada as the main element of the Imperial Wireless Chain
Imperial Wireless Chain
The Imperial Wireless Chain, also known as the Empire Wireless Chain, was a strategic international wireless telegraphy communications network, created to link the countries of the British Empire. Although the idea was conceived prior to World War I, Britain was the last of the world's Great Powers...

. The UK-to-Canada shortwave "Beam Wireless Service" went into commercial operation on 25 October 1926. Beam Wireless Services from the UK to Australia, South Africa and India went into service in 1927. Electronic components for the system were built at Marconi's New Street wireless factory in Chelmsford
Chelmsford
Chelmsford is the county town of Essex, England and the principal settlement of the borough of Chelmsford. It is located in the London commuter belt, approximately northeast of Charing Cross, London, and approximately the same distance from the once provincial Roman capital at Colchester...

.

Marconi would jointly receive the 1909 Nobel Prize in Physics
Nobel Prize in Physics
The Nobel Prize in Physics is awarded once a year by the Royal Swedish Academy of Sciences. It is one of the five Nobel Prizes established by the will of Alfred Nobel in 1895 and awarded since 1901; the others are the Nobel Prize in Chemistry, Nobel Prize in Literature, Nobel Peace Prize, and...

 with Karl Ferdinand Braun
Karl Ferdinand Braun
Karl Ferdinand Braun was a German inventor, physicist and Nobel laureate in physics. Braun contributed significantly to the development of the radio and television technology: he shared with Guglielmo Marconi the 1909 Nobel Prize in Physics.-Biography:Braun was born in Fulda, Germany, and...

 for contributions to the existing radio sciences. Marconi's demonstrations of the use of radio for wireless communications, equipping ships with life saving wireless communications, establishing the first transatlantic radio service, and building the first stations for the British short wave service, have marked his place in history. Shortly after the turn of the 20th century, the US Patent Office re-awarded Marconi a patent for radio. The was granted on June 4, 1901. Marconi's was awarded on June 11, 1901, also. This system was more advanced than his previous works. In 1943, a lawsuit regarding Marconi's early United States radio patents were resolved by the United States Supreme Court, who overturned most of these.

Naval wireless


The United States Navy Board had issued a 1899 report on the results of investigations of the Marconi system of wireless telegraphy. The report, Notes On The Marconi Wireless Telegraphy was published in full in the Electrician, and from it the following statements concerning the efficiency of the system have been taken: It was well adapted for use in squadron signalling under conditions of rain, fog, darkness and motion of speed. Wind, rain, fog, and other conditions of weather do not affect the transmission through space, but dampness may reduce the range, rapidity, and accuracy by impairing the insulation of the aerial wire and the instruments. Darkness has no effect. When two transmitters are sending at the same time, all the receiving wires within range receive the impulses from transmitters, and the tapes, although unreadable, show unmistakably that such double sending was taking place. In every case, under a great number of varied conditions, the attempted interference was complete. Marconi, although he stated to the Board before these attempts were made that he could prevent interference, never explained how nor made any attempt to demonstrate that it could be done. Between large ships (heights of masts 130 feet (39.6 m) and 140 feet (42.7 m)) and a torpedo-boat (height of mast 45 feet (13.7 m)), across open water, signals can be read up to 7 miles (11.3 km) on the torpedo-boat and 85 miles (136.8 km) on the ship
Naval ship
A naval ship is a ship used for combat purposes, commonly by a navy. Naval ships are differentiated from civilian ships by construction and purpose...

. Communication might be interrupted altogether when tall buildings of iron framing intervene. The rapidity was not greater than twelve words per minute for skilled operators. The sending apparatus and wire would injuriously affect the compass if placed near it. The exact distance were not known, and would be determined by experiment. The system was adapted for use on all vessels of the navy, including torpedo-boats and small vessels, as patrol boat
Patrol boat
A patrol boat is a relatively small naval vessel generally designed for coastal defense duties.There have been many designs for patrol boats. They may be operated by a nation's navy, coast guard, or police force, and may be intended for marine and/or estuarine or river environments...

s, scout boats, and despatch boats, but it was impracticable in a small boat. For landing parties the only feasible method of use would be to erect a pole on shore
Antenna (radio)
An antenna is an electrical device which converts electric currents into radio waves, and vice versa. It is usually used with a radio transmitter or radio receiver...

 and then communicate with the ship. The system could be adapted to the telegraphic determination of differences of longitude
Longitude
Longitude is a geographic coordinate that specifies the east-west position of a point on the Earth's surface. It is an angular measurement, usually expressed in degrees, minutes and seconds, and denoted by the Greek letter lambda ....

 in surveying
Surveying
See Also: Public Land Survey SystemSurveying or land surveying is the technique, profession, and science of accurately determining the terrestrial or three-dimensional position of points and the distances and angles between them...

. The Board respectfully recommended that the system be given a trial in the United States Navy
United States Navy
The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...

.

The HMS Hector
HMS Hector (1862)
HMS Hector was the lead ship of the armoured frigates ordered by the Royal Navy in 1861. Upon completion in 1864 she was assigned to the Channel Fleet. The ship was paid off in 1867 to refit and be re-armed. Upon recommissioning in 1868 she was assigned as the guard ship of the Fleet Reserve in...

became the first British warship to have wireless telegraphy
Wireless telegraphy
Wireless telegraphy is a historical term used today to apply to early radio telegraph communications techniques and practices, particularly those used during the first three decades of radio before the term radio came into use....

 installed when she conducted the first trials of the new equipment for the Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

. Starting in December 1899, the HMS Hector and HMS Jaseur were outfitted with wireless equipment. In 1901, HMS Jaseur
HMS Jaseur
Six ships of the Royal Navy have borne the name HMS Jaseur, the name coming from the French for the Waxwing. was a 12-gun brig-sloop that captured off the Andaman Islands in 1807. was a Cruizer-class brig-sloop launched in 1813 and sold in 1847. was a wood screw gunboat launched in 1857 and...

 received signals from the Marconi transmitter on the Isle of Wight and from the HMS Hector (25 January).

Stone Stone


John Stone Stone
John Stone Stone
John Stone Stone was an American mathematician, physicist and inventor. He labored as an early telephone engineer, was influential in developing wireless communication technology, and holds dozens of key patents in the field of "space telegraphy".-Early years:Stone was born in Dover, now Manakin...

 labored as an early telephone engineer and was influential in developing wireless communication technology, and holds dozens of key patent
Patent
A patent is a form of intellectual property. It consists of a set of exclusive rights granted by a sovereign state to an inventor or their assignee for a limited period of time in exchange for the public disclosure of an invention....

s in the field of "space telegraphy". Patents of Stone for radio, together with their equivalents in other countries, form a very voluminous contribution to the patent literature of the subject. More than seventy United States patents have been granted to this patentee alone. In many cases these specifications are learned contributions to the literature of the subject, filled with valuable references to other sources of information. A complete analysis of Stone's specifications would occupy too much space. Broadly speaking, they may be divided into four classes:
  • Those concerned with proposed methods for the achievement of syntonic telegraphy, or the isolation of receiving stations or protection of receivers from the action of vagrant waves.
  • Those describing forms of electric wave detector or cymoscope.
  • Those covering the construction of various forms of transmitting
    Transmitter
    In electronics and telecommunications a transmitter or radio transmitter is an electronic device which, with the aid of an antenna, produces radio waves. The transmitter itself generates a radio frequency alternating current, which is applied to the antenna. When excited by this alternating...

     and receiving circuit
    Receiver (radio)
    A radio receiver converts signals from a radio antenna to a usable form. It uses electronic filters to separate a wanted radio frequency signal from all other signals, the electronic amplifier increases the level suitable for further processing, and finally recovers the desired information through...

    , and the production of continuous trains of wave
    Continuous wave
    A continuous wave or continuous waveform is an electromagnetic wave of constant amplitude and frequency; and in mathematical analysis, of infinite duration. Continuous wave is also the name given to an early method of radio transmission, in which a carrier wave is switched on and off...

    s.
  • Miscellaneous specifications covering devices proposed for localizing the direction of the arriving waves and other matters.


Stone has had issued to him a large number of patents embracing a method for impressing oscillations on a radiator system and emitting the energy in the form of waves of predetermined length whatever may be the electrical dimensions of the oscillator. On February 8, 1900, he filed for a selective system in . In this system, two simple circuits are associated inductively, each having an independent degree of freedom, and in which the restoration of electric oscillations to zero potential the currents are superimposed, giving rise to compound harmonic currents which permit the resonator system to be syntonized with precision to the oscillator. Stone's system, as stated in , developed free or unguided simple harmonic electromagnetic signal waves of a definite frequency to the exclusion of the energy of signal waves of other frequencies, and an elevated conductor and means for developing therein forced simple electric vibrations of corresponding frequency. In these patents Stone devised a multiple inductive oscillation circuit with the object of forcing on the antenna circuit a single oscillation of definite frequency. In the system for receiving the energy of free or unguided simple harmonic electromagnetic signal waves of a definite frequency to the exclusion of the energy of signal waves of other frequencies, he claimed an elevated conductor and a resonant circuit associated with said conductor and attuned to the frequency of the waves, the energy of which is to be received. A coherer made on what is called the Stone system was employed in some of the portable wireless outfits of the United States Army
United States Army
The United States Army is the main branch of the United States Armed Forces responsible for land-based military operations. It is the largest and oldest established branch of the U.S. military, and is one of seven U.S. uniformed services...

. The Stone Coherer has two small steel plugs between which are placed loosely packed carbon granules. This is a self-decohering device; though not as sensitive as other forms of detectors it is well suited to the rough usage of portable outfits.

Fessenden


In late 1886, Reginald A. Fessenden began working directly for Thomas Edison at the inventor's new laboratory in West Orange, New Jersey
West Orange, New Jersey
West Orange is a township in central Essex County, New Jersey, United States. As of the 2010 United States Census, the township population was 46,207...

. Fessenden quickly made major advances, especially in receiver design, as he worked to develop audio reception of signals. Fessenden's initial United States patents were and and are companion patents. One concerns the methods and the other the devices of the same system. The United States Weather Bureau began, early in 1900, a systematic course of experimentation in wireless telegraphy, employing him as a specialist. Fessenden evolved the heterodyne
Heterodyne
Heterodyning is a radio signal processing technique invented in 1901 by Canadian inventor-engineer Reginald Fessenden where high frequency signals are converted to lower frequencies by combining two frequencies. Heterodyning is useful for frequency shifting information of interest into a useful...

 principle here where two signals combined to produce a third audible tone.

In 1900, construction began on a large radio transmitting dynamo. Fessenden, experimenting with a high-frequency spark transmitter, successfully transmitted speech on December 23, 1900 over a distance of about 1.6 kilometre (0.994196378639691 mi), the first audio radio transmission. Early in 1901 the Weather Bureau officially installed Fessenden at Wier's Point, Roanoke Island
Roanoke Island
Roanoke Island is an island in Dare County near the coast of North Carolina, United States. It was named after the historical Roanoke Carolina Algonquian people who inhabited the area in the 16th century at the time of English exploration....

, North Carolina
North Carolina
North Carolina is a state located in the southeastern United States. The state borders South Carolina and Georgia to the south, Tennessee to the west and Virginia to the north. North Carolina contains 100 counties. Its capital is Raleigh, and its largest city is Charlotte...

, and he made experimental transmissions across water to a station located about 5 miles (8 km) west of Cape Hatteras
Cape Hatteras
Cape Hatteras is a cape on the coast of North Carolina. It is the point that protrudes the farthest to the southeast along the northeast-to-southwest line of the Atlantic coast of North America...

, the distance between the two stations being almost exactly 50 miles (80.5 km). A dynamo of 1 kW output at 10 kilohertz was built in 1902. The credit for the development of this machine is due to Charles Proteus Steinmetz
Charles Proteus Steinmetz
Charles Proteus Steinmetz was a German-American mathematician and electrical engineer. He fostered the development of alternating current that made possible the expansion of the electric power industry in the United States, formulating mathematical theories for engineers...

, Caryl D. Haskins, Ernst Alexanderson
Ernst Alexanderson
Ernst Frederick Werner Alexanderson was a Swedish-American electrical engineer, who was a pioneer in radio and television development.-Background:...

, John T. H. Dempster, Henry Geisenhoner, Adam Stein, Jr., and F. P. Mansbendel.

In a paper written by Fessenden in 1902, it was asserted that important advances had been made, one of which was overcoming largely the loss of energy experienced in other systems. He also declared that syntony was not safely selecting, but that he had discovered several methods which were. In an interview with a New York Journal correspondent, Fessenden stated that in his early apparatus he did not use an air transformer at the sending end, nor a concentric cylinder for emitters and antennae, and had used capacity, but arranged in a manner entirely different from that in other systems, and that he did not employ a coherer or any form of imperfect contact. His apparatus was of solid metal, and, according to Fessenden, acted under a physical law entirely different from that which governs the receiving devices of Marconi. Fessenden asserted that he had paid particular attention to selective and multiplex
Multiplexing
The multiplexed signal is transmitted over a communication channel, which may be a physical transmission medium. The multiplexing divides the capacity of the low-level communication channel into several higher-level logical channels, one for each message signal or data stream to be transferred...

 systems, and was well satisfied with the results in that direction. On August 12, 1902, 13 patents were issued to Fessenden, covering various methods, devices, and systems for signaling without wires. These patents involved many new principles, the chef-d'oeuvre of which was a method for distributing capacity and inductance
Distributed element model
In electrical engineering, the distributed element model or transmission line model of electrical circuits assumes that the attributes of the circuit are distributed continuously throughout the material of the circuit...

 instead of localizing these coefficients of the oscillator as in previous systems.

By the summer of 1906, a machine producing 50 kilohertz
Low frequency
Low frequency or low freq or LF refers to radio frequencies in the range of 30 kHz–300 kHz. In Europe, and parts of Northern Africa and of Asia, part of the LF spectrum is used for AM broadcasting as the longwave band. In the western hemisphere, its main use is for aircraft beacon,...

 was installed at the Brant Rock station, and in the fall of 1906, the electric alternating dynamo
Alternator
An alternator is an electromechanical device that converts mechanical energy to electrical energy in the form of alternating current.Most alternators use a rotating magnetic field but linear alternators are occasionally used...

 was working regularly at 75 kilohertz, with an output of 0.5 kW.
Fessenden used this for wireless telephoning to Plymouth
Plymouth
Plymouth is a city and unitary authority area on the coast of Devon, England, about south-west of London. It is built between the mouths of the rivers Plym to the east and Tamar to the west, where they join Plymouth Sound...

, a distance of approximately 11 miles (17.7 km). In the following year machines were constructed having a frequency of 96 kilohertz and outputs of 1 kW and 2 kW. Fessenden believed that the damped wave-coherer system was essentially and fundamentally incapable of development into a practical system. He would employ a two-phase high frequency
High frequency
High frequency radio frequencies are between 3 and 30 MHz. Also known as the decameter band or decameter wave as the wavelengths range from one to ten decameters . Frequencies immediately below HF are denoted Medium-frequency , and the next higher frequencies are known as Very high frequency...

 dynamo method and the continuous production of waves
Continuous wave
A continuous wave or continuous waveform is an electromagnetic wave of constant amplitude and frequency; and in mathematical analysis, of infinite duration. Continuous wave is also the name given to an early method of radio transmission, in which a carrier wave is switched on and off...

 with changing constants of sending circuit. Fessenden would also use duplex and multiplex commutator methods. On Dec. 11, 1906, operation of the wireless transmission in conjunction with the wire lines took place. In July 1907 the range was considerably extended and speech was successfully transmitted between Brant Rock and Jamaica, Long Island, a distance of nearly 200 miles (321.9 km), in daylight and mostly over land, the mast at Jamaica being approximately 180 feet (54.9 m) high.

Fleming


In November 1904, John Ambrose Fleming
John Ambrose Fleming
Sir John Ambrose Fleming was an English electrical engineer and physicist. He is known for inventing the first thermionic valve or vacuum tube, the diode, then called the kenotron in 1904. He is also famous for the left hand rule...

 invented the two-electrode vacuum-tube rectifier, which he called the Fleming oscillation valve. He would later patent this invention. This "Fleming Valve" was much used as a receiver for long-distance wireless on account of its sensitivity. It also had another advantage—that it could not be permanently injured or set out of adjustment by any exceptionally strong stray signal, such as those due to atmospheric electricity. For this reason it was the detector par excellence for large antenna or high-power stations.

Fleming recognized the use of the rectifying properties of a wireless tube for the indication of high frequency oscillations, and used it as a electromagnetic detector. On November 7, 1905, he would be granted . Marconi used this device as a radio detector, also.

The Supreme Court of the United States
Supreme Court of the United States
The Supreme Court of the United States is the highest court in the United States. It has ultimate appellate jurisdiction over all state and federal courts, and original jurisdiction over a small range of cases...

 would eventually invalidate the patent because of an improper disclaimer and, additionally, maintained the technology in the patent was known art when filed. This invention was the first vacuum tube
Vacuum tube
In electronics, a vacuum tube, electron tube , or thermionic valve , reduced to simply "tube" or "valve" in everyday parlance, is a device that relies on the flow of electric current through a vacuum...

. Fleming's diode
Diode
In electronics, a diode is a type of two-terminal electronic component with a nonlinear current–voltage characteristic. A semiconductor diode, the most common type today, is a crystalline piece of semiconductor material connected to two electrical terminals...

 was used in radio receivers for many decades afterward, until it was superseded by solid state
Solid state (electronics)
Solid-state electronics are those circuits or devices built entirely from solid materials and in which the electrons, or other charge carriers, are confined entirely within the solid material...

 electronic technology more than 50 years later.

De Forest


Lee De Forest
Lee De Forest
Lee De Forest was an American inventor with over 180 patents to his credit. De Forest invented the Audion, a vacuum tube that takes relatively weak electrical signals and amplifies them. De Forest is one of the fathers of the "electronic age", as the Audion helped to usher in the widespread use...

 had an interest in wireless telegraphy and he invented the Audion
Audion tube
The Audion is an electronic amplifying vacuum tube invented by Lee De Forest in 1906. It was the forerunner of the triode, in which the current from the filament to the plate was controlled by a third element, the grid...

 in 1906. He was president and secretary of the De Forest Radio Telephone and Telegraph Company (1913). The De Forest System was adopted by the United States Government, and had been demonstrated to other Governments including those of Great Britain, Denmark, Germany, Russia, and British Indies, all of which purchased De Forest apparatus previous to the Great War. De Forest is one of the fathers of the "electronic age", as the Audion helped to usher in the widespread use of electronics
Electronics
Electronics is the branch of science, engineering and technology that deals with electrical circuits involving active electrical components such as vacuum tubes, transistors, diodes and integrated circuits, and associated passive interconnection technologies...

.

De Forest made the Audion tube from a vacuum tube
Vacuum tube
In electronics, a vacuum tube, electron tube , or thermionic valve , reduced to simply "tube" or "valve" in everyday parlance, is a device that relies on the flow of electric current through a vacuum...

. He also made the "Oscillion", an undamped wave transmitter. He developed the De Forest method of wireless telegraphy and founded the American De Forest Wireless Telegraph Company. De Forest was a distinguished electrical engineer and the foremost American contributor to the development of wireless telegraphy and telephony. The elements of his device takes relatively weak electrical signals and amplifies them. The Audion Detector, Audion Amplifier, and the "Oscillion" transmitter had furthered the radio art and the transmission of written or audible speech. In World War I
World War I
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

, the De Forest system was a factor in the efficiency of the United States Signal Service, and was also installed by the United States Government in Alaska.

Formative stage

Name Pro Con Earliest transmission
Henry
Joseph Henry
Joseph Henry was an American scientist who served as the first Secretary of the Smithsonian Institution, as well as a founding member of the National Institute for the Promotion of Science, a precursor of the Smithsonian Institution. During his lifetime, he was highly regarded...

Henry detected electromagnetic effects at a distance of two hundred feet. He was focused on wired telegraphy and researched self-inductance. 1829
Hughes
David E. Hughes
David Edward Hughes , was a British scientist and musician. Hughes was co-inventor of the microphone, a harpist and a professor of music.-Biography:...

In 1879, Hughes began research into radio waves. He noticed electrical interference in an induction balance he was working with. The observed effect was due to radio waves and he discovered and improved the coherer. Hughes was not trying to design equipment for wireless communication. His discovery was taken no further. 1879
Maxwell
James Clerk Maxwell
James Clerk Maxwell of Glenlair was a Scottish physicist and mathematician. His most prominent achievement was formulating classical electromagnetic theory. This united all previously unrelated observations, experiments and equations of electricity, magnetism and optics into a consistent theory...

By 1864 Maxwell had become the first person to demonstrate theoretically the existence of radio (electromagnetic) waves, which are used by all radio equipment. Maxwell did not generate or receive radio waves. None (n/a)


Early developers

Name Pro Con Earliest transmission
Branly
Edouard Branly
Édouard Eugène Désiré Branly was a French inventor, physicist and professor at the Institut Catholique de Paris. He is primarily known for his early involvement in wireless telegraphy and his invention of the Branly coherer around 1890.-Biography:The coherer was the first widely used detector for...

Researched coherers. In 1890 Branly showed that such a tube would respond to sparks produced at a distance from it. Others would expound upon the idea of using such a tube. 1890
Bose
Jagdish Chandra Bose
Acharya Sir Jagadish Chandra Bose, CSI, CIE, FRS was a Bengali polymath: a physicist, biologist, botanist, archaeologist, as well as an early writer of science fiction...

Researched coherers.

Transmitted microwaves over distance of 75 feet in 1895.

Had transmitted microwaves nearly a mile by 1896.
Did not pursue commercialization. 1895
de Moura
Early Transmission (c. 1893)

Publicly demonstrated a radio broadcast of the human voice (1900)
Exhibition of the his apparatus occurred in 1900 1900
Braun Invented closed circuit and coupled coils for transmitters. Did not recognize the significance when Hertz published his findings in 1888. 1897
Hertz By 1888, Hertz had studied and understood the work of Maxwell and, by design, produced the first clear and undisputed experimental evidence for the transmission and reception of radio waves. Hertz took this work no further, did not exploit it commercially, and famously did not consider it useful. 1888
Lodge Awarded the "syntonic" (or tuning) US Patent
Rutherford
Ernest Rutherford
Ernest Rutherford, 1st Baron Rutherford of Nelson OM, FRS was a New Zealand-born British chemist and physicist who became known as the father of nuclear physics...

Developed sensitive apparatus until he could detect electromagnetic waves over a distance of several hundred meters.
Tesla
Nikola Tesla
Nikola Tesla was a Serbian-American inventor, mechanical engineer, and electrical engineer...


Early Transmission (1893)

Tesla developed means to reliably produce radio frequency currents.

In 1891 and afterwards, lectured about high-frequency devices and demonstrated devices using power without the use of wires.

Referring to a demonstration of his wireless equipment in 1893 the IEE said "the apparatus that he employed contained all the elements of spark and continuous wave that were incorporated into radio transmitters before the advent of the vacuum tube".

By 1895, stated that he had the ability to transmit signals under 50 miles.

In 1897, Tesla applied for protection for the radio arts.
In 1898, demonstrated a radio control
Radio control
Radio control is the use of radio signals to remotely control a device. The term is used frequently to refer to the control of model vehicles from a hand-held radio transmitter...

 and secure communication
Secure communication
When two entities are communicating and do not want a third party to listen in, they need to communicate in a way not susceptible to eavesdropping or interception. This is known as communicating in a secure manner or secure communication...

 between transmitter and receiver.

After 1915, assisted the Telefunken
Telefunken
Telefunken is a German radio and television apparatus company, founded in Berlin in 1903, as a joint venture of Siemens & Halske and the Allgemeine Elektricitäts-Gesellschaft...

 engineers in constructing the Telefunken Wireless Station (the "Arco
Georg von Arco
Georg Wilhelm Alexander Hans Graf von Arco was a German physicist, radio pioneer, and one of the joint founders of the "Society for Wireless Telegraphy" which became the Telefunken company. He was an engineer and the technical director of Telefunken...

-Slaby
Adolf Slaby
Adolf Karl Heinrich Slaby was a German wireless pioneer and the first Professor of electro-technology at the Technical University of Berlin .-Education:Slaby was born in Berlin, the son of a bookbinder...

 system") in Sayville, Long Island.

Primarily because of financial difficulties, Tesla never completed his "worldwide wireless system". The Wardenclyffe Tower
Wardenclyffe Tower
Wardenclyffe Tower also known as the Tesla Tower, was an early wireless telecommunications tower designed by Nikola Tesla and intended for commercial trans-Atlantic wireless telephony, broadcasting, and to demonstrate the transmission of power without interconnecting wires...

 transceiver that he began at Shoreham
Shoreham, New York
Shoreham is an incorporated village in Suffolk County, New York, United States. The population was 417 at the 2000 census.The Incorporated Village of Shoreham is inside the Town of Brookhaven.-Geography:Shoreham is located at ....

 on Long Island, New York was eventually torn down.

According to L. Gualandi, Tesla's apparatus was not meant to be used in radio-transmission applications. Unlike Marconi's system no technical solution was present to allow the reception and transmission of long distance radio-signal.
c. 1892


Later developers

Name Pro Con Earliest transmission
Baviera
Julio Cervera Baviera
Julio Cervera Baviera was a Spanish engineer, pioneer in the development of radio, educator, explorer, and military man. He also authored various scientific and geographic books and articles.-Education:...

He was the first person to be granted a patent regarding a radiotelephonic system in 1899. His activities on this field ceased suddenly, the reasons for which are unclear to this day. 1899
DeForest
Lee De Forest
Lee De Forest was an American inventor with over 180 patents to his credit. De Forest invented the Audion, a vacuum tube that takes relatively weak electrical signals and amplifies them. De Forest is one of the fathers of the "electronic age", as the Audion helped to usher in the widespread use...

Developed the triode amplifier and the Audion tube
Audion tube
The Audion is an electronic amplifying vacuum tube invented by Lee De Forest in 1906. It was the forerunner of the triode, in which the current from the filament to the plate was controlled by a third element, the grid...

.
Late upon beginning research into space telegraphy. 1896
Fessenden
Reginald Fessenden
Reginald Aubrey Fessenden , a naturalized American citizen born in Canada, was an inventor who performed pioneering experiments in radio, including early—and possibly the first—radio transmissions of voice and music...

First audio transmission by radio (1900). Also, the first two-way transatlantic radio transmission (1906), and the first radio broadcast of entertainment and music (1906) 1900
Fleming
John Ambrose Fleming
Sir John Ambrose Fleming was an English electrical engineer and physicist. He is known for inventing the first thermionic valve or vacuum tube, the diode, then called the kenotron in 1904. He is also famous for the left hand rule...

Known for inventing the first thermionic valve.
Marconi
Guglielmo Marconi
Guglielmo Marconi was an Italian inventor, known as the father of long distance radio transmission and for his development of Marconi's law and a radio telegraph system. Marconi is often credited as the inventor of radio, and indeed he shared the 1909 Nobel Prize in Physics with Karl Ferdinand...

Marconi was the first scientist to achieve successful radio transmission. In summer 1895, Marconi sent signals 1.5 miles.
Developed Marconi's Law
Marconi's law
Marconi's law is the relation between height of antennae and maximum signalling distance. Guglielmo Marconi enunciated at one time an empirical law that, for simple vertical sending and receiving antennae of equal height, the maximum working telegraphic distance varied as the square of the height...

.

In 1896, applied for British patent protection for a radio system. In 1900, he was granted British patent No. 12,039.

Transmission over 6 km in March and May 1897.

Transatlantic transmission on 12 December 1901.

Transmission over 3,378 km in February 1902.

Transatlantic message on 17 December 1902.

In 1897 Marconi founded "Wireless Telegraph and Signal Company" and exploited the "Marconi System" of radio commercially.

He shared the 1909 Nobel Prize in Physics with Karl Ferdinand Braun, "in recognition of their contributions to the development of wireless telegraphy".
Many of Marconi's system components were developed by others. According to the Proceedings of the United States Naval Institute
United States Naval Institute
The United States Naval Institute , based at the United States Naval Academy in Annapolis, Maryland, is a private, non-profit, professional military association that seeks to offer independent, nonpartisan forums for debate of national defense issues...

, the Marconi instruments were tested around 1899 and the tests concerning his wireless system found that the "[...] coherer, principle of which was discovered some twenty years ago, [was] the only electrical instrument or device contained in the apparatus that is at all new". Oliver Lodge claimed British patent of 1900 to contain his own ideas which he failed to patent.

His 1901 transatlantic transmission is disputed.
1895
Popov Confirmed laboratory demonstration of radio on 7 May 1895. In 1896 or 1897 publicly demonstrated the sending of a signal 250 m between two campus buildings. By 1900 he had reliable communications over 25 miles. 1895
Stone
John Stone Stone
John Stone Stone was an American mathematician, physicist and inventor. He labored as an early telephone engineer, was influential in developing wireless communication technology, and holds dozens of key patents in the field of "space telegraphy".-Early years:Stone was born in Dover, now Manakin...

Influential in developing wireless communication technology

Holds dozens of key patents in the field of "space telegraphy".


Radio invention timeline


Below is a selection of pertinent events and individuals, from 1860 to 1910, related to the development of radio.

See also


People: Edwin Howard Armstrong, Greenleaf Whittier Pickard
Greenleaf Whittier Pickard
Greenleaf Whittier Pickard was a United States radio pioneer. Pickard was a researcher in the early days of wireless. He experimented with crystal detectors, antennas, wave propagation, and noise suppression...

, Ernst Alexanderson
Ernst Alexanderson
Ernst Frederick Werner Alexanderson was a Swedish-American electrical engineer, who was a pioneer in radio and television development.-Background:...

, Archie Frederick Collins
Archie Frederick Collins
Archie Frederick Collins was an early experimenter in wireless telephony and a prolific author of books and articles on a wide range of scientific and technical subjects....


Radio: Radio communication system
Radio communication system
A radio communication system sends signals by radio. Types of radio communication systems deployed depend on technology, standards, regulations, radio spectrum allocation, user requirements, service positioning, and investment....

, Timeline of radio
Timeline of radio
The timeline of radio lists within the history of radio, the technology and events that produced instruments that use radio waves and activities that people undertook...

, Oldest radio station, Birth of public radio broadcasting
Birth of public radio broadcasting
Birth of public radio broadcasting is credited to Lee de Forest. A 1907 Lee De Forest company advertisement said, -Date:On January 13, 1910, the first public radio broadcast was an experimental transmission of a live Metropolitan Opera House performance of several famous opera...

, Crystal radio
Categories: Radio People, Radio Pioneers, Discovery and invention controversies
Other: List of persons considered father or mother of a field, Radiotelegraph and Spark-Gap Transmitter
Spark-gap transmitter
A spark-gap transmitter is a device for generating radio frequency electromagnetic waves using a spark gap.These devices served as the transmitters for most wireless telegraphy systems for the first three decades of radio and the first demonstrations of practical radio were carried out using them...

s, The Great Radio Controversy
The Great Radio Controversy
The Great Radio Controversy is the second album by American rock band Tesla, released in 1989. The songs combine 1980s metal with some blues-influenced elements, as well as the occasional love ballad...

, Induction coil
Induction coil
An induction coil or "spark coil" is a type of disruptive discharge coil. It is a type of electrical transformer used to produce high-voltage pulses from a low-voltage direct current supply...

, Ruhmkorff coil, Poldhu
Poldhu
Poldhu is a small area in south Cornwall, England, UK, situated on the Lizard Peninsula; it comprises Poldhu Point and Poldhu Cove. It lies on the coast west of Goonhilly Downs, with Mullion to the south and Porthleven to the north...

, Alexanderson alternator
Alexanderson alternator
An Alexanderson alternator is a rotating machine invented by Ernst Alexanderson in 1904 for the generation of high frequency alternating current up to 100 kHz, for use as a radio transmitter...

, De Forest tube

Further reading

  • Anderson, L.I., "Priority in the Invention of Radio: Tesla vs. Marconi", Antique Wireless Association Monograph No. 4, March, 1980.
  • Anderson, L.I., "John Stone Stone on Nikola Tesla's Priority in Radio and Continuous-Wave Radiofrequency Apparatus", The A.W.A. (Antique Wireless Association) Review, Vol. 1, 1986, pp. 18–41.
  • Brand, W.E., "Rereading the Supreme Court: Tesla's Invention of Radio", Antenna, Volume 11 No. 2, May 1998, Society for the History of Technology
  • Lauer, H., & Brown, H. L. (1919). Radio engineering principles. New York: McGraw-Hill book company; [etc., etc.]
  • Rockman, H. B. (2004). Intellectual property law for engineers and scientists. New York [u.a.: IEEE Press].

External links


United States Court case

Books and articles:listed by date, earliest first

Encyclopedias

Gutenberg project

Websites