The
cavity magnetron is a high-powered
vacuum tubeIn 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...
that generates
microwaveMicrowaves, a subset of radio waves, have wavelengths ranging from as long as one meter to as short as one millimeter, or equivalently, with frequencies between 300 MHz and 300 GHz. This broad definition includes both UHF and EHF , and various sources use different boundaries...
s using the interaction of a stream of electrons with a magnetic field. The 'resonant' cavity magnetron variant of the earlier magnetron tube was invented by
John RandallSir John Turton Randall, FRS, FRSE, was a British physicist and biophysicist, credited with radical improvement of the cavity magnetron, an essential component of centimetric wavelength radar, which was one of the keys to the Allied victory in the Second World War. It is also the key component of...
and
Harry BootHenry Albert Howard "Harry" Boot was an English physicist who with Sir John Randall and James Sayers developed the cavity magnetron, which was one of the keys to the Allied victory in the Second World War.-Biography:...
in 1940 at the University of Birmingham, England. The high power of pulses from the cavity magnetron made centimeter-band
radarRadar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...
practical. Shorter wavelength radars allowed detection of smaller objects. The compact cavity magnetron tube drastically reduced the size of radar sets so that they could be installed in anti-submarine aircraft and escort ships. At present, cavity magnetrons are commonly used in
microwave ovenA microwave oven is a kitchen appliance that heats food by dielectric heating, using microwave radiation to heat polarized molecules within the food...
s and in various
radarRadar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...
applications.
Construction and operation
All cavity magnetrons consist of a hot cathode with a high (continuous or pulsed) negative potential by a high-voltage, direct-current power supply. The
cathodeA cathode is an electrode through which electric current flows out of a polarized electrical device. Mnemonic: CCD .Cathode polarity is not always negative...
is built into the center of an evacuated, lobed, circular chamber. A magnetic field parallel to the filament is imposed by a permanent magnet. The magnetic field causes the electrons, attracted to the (relatively) positive outer part of the chamber, to spiral outward in a circular path rather than moving directly to this
anodeAn anode is an electrode through which electric current flows into a polarized electrical device. Mnemonic: ACID ....
. Spaced around the rim of the chamber are cylindrical cavities. The cavities are open along their length and connect the common cavity space. These cavities act just like very highly efficient tuned circuits. As electrons sweep past these openings, they induce a resonant, high-frequency radio field in the cavity, which in turn causes the electrons to bunch into groups. The principle is very similar to blowing a stream of air across the open top of a glass pop bottle. The cavities resonate, and emit a powerful radio-frequency energy output. A portion of this field is extracted with a short antenna that is connected to a
waveguideIn electromagnetics and communications engineering, the term waveguide may refer to any linear structure that conveys electromagnetic waves between its endpoints. However, the original and most common meaning is a hollow metal pipe used to carry radio waves...
(a metal tube usually of rectangular cross section). The waveguide directs the extracted RF energy to the load, which may be a cooking chamber in a microwave oven or a high-gain
antennaAn 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...
in the case of radar.
The sizes of the cavities determine the resonant frequency, and thereby the frequency of emitted microwaves. However, the frequency is not precisely controllable. The operating frequency varies with changes in load impedance, with changes in the supply current, and with the temperature of the tube. This is not a problem in uses such as heating, or in some forms of
radarRadar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...
where the receiver can be synchronized with an imprecise magnetron frequency. Where precise frequencies are needed, other devices such as the
klystronA klystron is a specialized linear-beam vacuum tube . Klystrons are used as amplifiers at microwave and radio frequencies to produce both low-power reference signals for superheterodyne radar receivers and to produce high-power carrier waves for communications and the driving force for modern...
are used.
The magnetron is a self-oscillating device requiring no external elements other than a power supply. A well-defined threshold anode voltage must be applied before oscillation will build up; this voltage is a function of the dimensions of the resonant cavity, and the applied magnetic field. In pulsed applications there is a delay of several cycles before the oscillator achieves full peak power, and the build-up of anode voltage must be coordinated with the build-up of oscillator output.
The magnetron is a fairly efficient device. In a microwave oven, for instance, a 1.1 kilowatt input will generally create about 700 watt of microwave power, an efficiency of around 65%. (The high-voltage and the properties of the cathode determine the power of a magnetron.) Large S-band magnetrons can produce up to 2.5 megawatts peak power with an average power of 3.75 kW. Large magnetrons can be water cooled. The magnetron remains in widespread use in roles which require high power, but where precise frequency control is unimportant.
Applications
Radar
In
radarRadar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...
devices, the waveguide is connected to an antenna. The magnetron is operated with very short pulses of applied voltage, resulting in a short pulse of high power microwave energy being radiated. As in all radar systems, the radiation reflected off a target is analyzed to produce a radar map on a screen.
Several characteristics of the magnetron's power output conspire to make radar use of the device somewhat problematic. The first of these factors is the magnetron's inherent instability in its transmitter frequency. This instability is noted not only as a frequency shift from one pulse to the next, but also a frequency shift within an individual transmitter pulse. The second factor is that the energy of the transmitted pulse is spread over a wide frequency spectrum, which makes necessary its receiver to have a corresponding wide selectivity. This wide selectivity permits ambient electrical noise to be accepted into the receiver, thus obscuring somewhat the received radar echoes, thereby reducing overall radar performance. The third factor, depending on application, is the radiation hazard caused by the use of high power electromagnetic radiation. In some applications, for example a marine radar mounted on a recreational vessel, a radar with a magnetron output of 2 to 4 kilowatts is often found mounted very near an area occupied by crew or passengers. In practical use, these factors have been overcome, or merely accepted, and there are today thousands of magnetron aviation and marine radar units in service. Recent advances in aviation weather avoidance radar and in marine radar have successfully implemented semiconductor transmitters that eliminate the magnetron entirely.
Heating
In
microwave ovenA microwave oven is a kitchen appliance that heats food by dielectric heating, using microwave radiation to heat polarized molecules within the food...
s, the waveguide leads to a radio frequency-transparent port into the cooking chamber.
Lighting
In microwave-excited lighting systems, such as a
sulfur lampThe sulfur lamp is a highly efficient full-spectrum electrodeless lighting system whose light is generated by sulfur plasma that has been excited by microwave radiation. The technology was developed in the early 1990s, but, although it appeared initially to be very promising, sulfur lighting was...
, a magnetron provides the microwave field that is passed through a waveguide to the lighting cavity containing the light-emitting substance (e.g., sulfur, metal halides, etc.)
History
The first simple, two-pole magnetron was developed in 1920 by
Albert HullAlbert W. Hull is most remembered for his early invention of the magnetron.-Education and early career:...
at
General ElectricGeneral Electric Company , or GE, is an American multinational conglomerate corporation incorporated in Schenectady, New York and headquartered in Fairfield, Connecticut, United States...
's Research Laboratories (Schenectady, New York), as an outgrowth of his work on the magnetic control of
vacuum tubeIn 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...
s in an attempt to work around the patents held by
Lee De ForestLee 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...
on electrostatic control.
Hull's magnetron was not originally intended to generate VHF (very-high-frequency) electromagnetic waves. However, in 1924, Czech physicist August Žáček (1886–1961) and German physicist Erich Habann (1892–1968) independently discovered that the magnetron could generate waves of 100 megahertz to 1 gigahertz. Žáček, a professor at Prague's Charles University, published first; however, he published in a journal with a small circulation and thus attracted little attention. Habann, a student at the University of Jena, investigated the magnetron for his doctoral dissertation of 1924. Throughout the 1920s, Hull and other researchers around the world worked to develop the magnetron. Most of these early magnetrons were glass vacuum tubes with multiple anodes. However, the two-pole magnetron, also known as a split-anode magnetron, had relatively low efficiency. The cavity version (properly referred to as a
resonant-cavity magnetron) proved to be far more useful. An early multi-cavity version of the magnetron was reported by Bucharest University Professor
Theodor V. IonescuTheodor V. Ionescu, Prof. Dr. Doc. was a Romanian physicist and inventor who made remarkable discoveries in plasma physics, ionosphere physics, ion coupling electrons in dense plasmas, masers, magnetron amplifiers, and Zeeman effects related to controlled nuclear fusion and quantum emission...
. and followed in 1937-1940 by a similar multi-cavity magnetron built by the British physicist,
Sir John Turton Randall, FRSEJohn Randall is the name of:*John Randall , mayor of Annapolis, Maryland and colonel in the American Revolution*Sir John Randall , British physicist, developer of the cavity magnetron...
together with a team of British coworkers for the British and American, military radar installations in WWII.
While
radarRadar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...
was being developed during
World War IIWorld War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
, there arose an urgent need for a high-power
microwaveMicrowaves, a subset of radio waves, have wavelengths ranging from as long as one meter to as short as one millimeter, or equivalently, with frequencies between 300 MHz and 300 GHz. This broad definition includes both UHF and EHF , and various sources use different boundaries...
generator that worked at shorter
wavelengthIn physics, the wavelength of a sinusoidal wave is the spatial period of the wave—the distance over which the wave's shape repeats.It is usually determined by considering the distance between consecutive corresponding points of the same phase, such as crests, troughs, or zero crossings, and is a...
s (around 10 cm (3 GHz)) rather than the 150 cm (200 MHz) that was available from tube-based generators of the time. It was known that a multi-cavity resonant magnetron had been developed and patented in 1935 by
Hans HollmannHans Erich Hollmann was a German electronic specialist who made several breakthroughs in the development of radar....
in
BerlinBerlin is the capital city of Germany and is one of the 16 states of Germany. With a population of 3.45 million people, Berlin is Germany's largest city. It is the second most populous city proper and the seventh most populous urban area in the European Union...
, and independently, in 1935, by physicist
Theodor V. IonescuTheodor V. Ionescu, Prof. Dr. Doc. was a Romanian physicist and inventor who made remarkable discoveries in plasma physics, ionosphere physics, ion coupling electrons in dense plasmas, masers, magnetron amplifiers, and Zeeman effects related to controlled nuclear fusion and quantum emission...
in Romania. However, the German military considered the frequency drift of Hollman's device to be undesirable, and based their radar systems on the
klystronA klystron is a specialized linear-beam vacuum tube . Klystrons are used as amplifiers at microwave and radio frequencies to produce both low-power reference signals for superheterodyne radar receivers and to produce high-power carrier waves for communications and the driving force for modern...
instead. But klystrons could not achieve the high power output that magnetrons eventually reached. This was one reason that German
night fighterA night fighter is a fighter aircraft adapted for use at night or in other times of bad visibility...
radars were not a match for their British counterparts.
In 1940, at the
University of BirminghamThe University of Birmingham is a British Redbrick university located in the city of Birmingham, England. It received its royal charter in 1900 as a successor to Birmingham Medical School and Mason Science College . Birmingham was the first Redbrick university to gain a charter and thus...
in the
United KingdomThe United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
,
John RandallSir John Turton Randall, FRS, FRSE, was a British physicist and biophysicist, credited with radical improvement of the cavity magnetron, an essential component of centimetric wavelength radar, which was one of the keys to the Allied victory in the Second World War. It is also the key component of...
and
Harry BootHenry Albert Howard "Harry" Boot was an English physicist who with Sir John Randall and James Sayers developed the cavity magnetron, which was one of the keys to the Allied victory in the Second World War.-Biography:...
produced a working prototype similar to Hollman's cavity magnetron, but added liquid cooling and a stronger cavity. Randall and Boot soon managed to increase its power output 100 fold. Instead of abandoning the magnetron due to its frequency instability, they sampled the output signal and synchronized their receiver to whatever frequency was actually being generated. In 1941, the problem of frequency instability was solved by coupling alternate cavities within the magnetron.
Because
FranceThe French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
had just fallen to the Nazis and Britain had no money to develop the magnetron on a massive scale, Churchill agreed that
Sir Henry TizardSir Henry Thomas Tizard FRS was an English chemist and inventor and past Rector of Imperial College....
should offer the magnetron to the Americans in exchange for their financial and industrial help (the
Tizard MissionThe Tizard Mission officially the British Technical and Scientific Mission was a British delegation that visited the United States during the Second World War in order to obtain the industrial resources to exploit the military potential of the research and development work completed by the UK up...
). An early 6 kW version, built in England by the General Electric Company Research Laboratories,
WembleyWembley is an area of northwest London, England, and part of the London Borough of Brent. It is home to the famous Wembley Stadium and Wembley Arena...
,
LondonLondon 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...
(not to be confused with the similarly named American company General Electric), was given to the US government in September 1940. At the time the most powerful equivalent microwave producer available in the US (a klystron) had a power of only ten watts. The cavity magnetron was widely used during
World War IIWorld War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
in microwave radar equipment and is often credited with giving Allied radar a considerable performance advantage over
GermanGermany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
and
JapanJapan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
ese radars, thus directly influencing the outcome of the war. It was later described by America as "the most valuable cargo ever brought to our shores".
The Bell Telephone Laboratories made a producible version from the magnetron delivered to America by the Tizard Mission, and before the end of 1940, the
Radiation LaboratoryThe Radiation Laboratory, commonly called the Rad Lab, was located at the Massachusetts Institute of Technology in Cambridge, Massachusetts and functioned from October 1940 until December 31, 1945...
had been set up on the campus of the
Massachusetts Institute of TechnologyThe Massachusetts Institute of Technology is a private research university located in Cambridge, Massachusetts. MIT has five schools and one college, containing a total of 32 academic departments, with a strong emphasis on scientific and technological education and research.Founded in 1861 in...
to develop various types of radar using the magnetron. By early 1941, portable centimetric airborne radars were being tested in American and British planes. In late 1941, the
Telecommunications Research EstablishmentThe Telecommunications Research Establishment was the main United Kingdom research and development organization for radio navigation, radar, infra-red detection for heat seeking missiles, and related work for the Royal Air Force during World War II and the years that followed. The name was...
in Great Britain used the magnetron to develop a revolutionary airborne, ground-mapping radar codenamed H2S. The
H2S radarH2S was the first airborne, ground scanning radar system. It was developed in Britain in World War II for the Royal Air Force and was used in various RAF bomber aircraft from 1943 to the 1990s. It was designed to identify targets on the ground for night and all-weather bombing...
was in part developed by
Alan BlumleinAlan Dower Blumlein was a British electronics engineer, notable for his many inventions in telecommunications, sound recording, stereo, television and radar...
and
Bernard LovellSir Alfred Charles Bernard Lovell OBE, FRS is an English physicist and radio astronomer. He was the first Director of Jodrell Bank Observatory, from 1945 to 1980.-Early Life:...
.
Centimetric radar, made possible by the cavity magnetron, allowed for the detection of much smaller objects and the use of much smaller antennas. The combination of small-cavity magnetrons, small antennas, and high resolution allowed small, high quality radars to be installed in aircraft. They could be used by maritime patrol aircraft to detect objects as small as a submarine periscope, which allowed aircraft to attack and destroy submerged submarines which had previously been undetectable from the air. Centimetric contour mapping radars like
H2SH2S was the first airborne, ground scanning radar system. It was developed in Britain in World War II for the Royal Air Force and was used in various RAF bomber aircraft from 1943 to the 1990s. It was designed to identify targets on the ground for night and all-weather bombing...
improved the accuracy of Allied bombers used in the
strategic bombing campaignStrategic bombing during World War II is a term which refers to all aerial bombardment of a strategic nature between 1939 and 1945 involving any nations engaged in World War II...
. Centimetric gun-laying radars were likewise far more accurate than the older technology. They made the big-gunned Allied battleships more deadly and, along with the newly developed
proximity fuzeA proximity fuze is a fuze that is designed to detonate an explosive device automatically when the distance to target becomes smaller than a predetermined value or when the target passes through a given plane...
, made anti-aircraft guns much more dangerous to attacking aircraft. The two coupled together and used by anti-aircraft batteries, placed along the flight path of German
V-1 flying bombThe V-1 flying bomb, also known as the Buzz Bomb or Doodlebug, was an early pulse-jet-powered predecessor of the cruise missile....
s on their way to
LondonLondon 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...
, are credited with destroying many of the flying bombs before they reached their target.
Since then, many millions of cavity magnetrons have been manufactured; while some have been for radar the vast majority have been for
microwave ovenA microwave oven is a kitchen appliance that heats food by dielectric heating, using microwave radiation to heat polarized molecules within the food...
s. The use in radar itself has dwindled to some extent, as more accurate signals have generally been needed and developers have moved to klystron and traveling-wave tube systems for these needs.
Health hazards
Among more speculative hazards, at least one in particular is well known and documented. As the lens of the
eyeThe human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...
has no cooling blood flow, it is particularly prone to overheating when exposed to microwave radiation. This heating can in turn lead to a higher incidence of
cataractA cataract is a clouding that develops in the crystalline lens of the eye or in its envelope, varying in degree from slight to complete opacity and obstructing the passage of light...
s in later life. A microwave oven with a warped door or poor microwave sealing can be hazardous.
There is also a considerable electrical hazard around magnetrons, as they require a high voltage power supply.
Some magnetrons have
beryllium oxideBeryllium oxide , also known as beryllia, is an inorganic compound with the formula BeO. This colourless solid is a notable electrical insulator with a higher thermal conductivity than any other non-metal except diamond, and actually exceeds that of some metals. As an amorphous solid, beryllium...
(beryllia) ceramic insulators, which are dangerous if crushed and inhaled, or otherwise ingested. Single or chronic exposure can lead to
berylliosisBerylliosis, or chronic beryllium disease , is a chronic allergic-type lung response and chronic lung disease caused by exposure to beryllium and its compounds. As an occupational lung disease, it is most classically associated with beryllium mining or manufacturing of fluorescent light bulbs...
, an incurable lung condition. In addition, beryllia is listed as a confirmed human carcinogen by the
IARCThe International Agency for Research on Cancer is an intergovernmental agency forming part of the World Health Organisation of the United Nations....
; therefore, broken ceramic insulators or magnetrons should not be directly handled.
See also
- Cyclotron
In technology, a cyclotron is a type of particle accelerator. In physics, the cyclotron frequency or gyrofrequency is the frequency of a charged particle moving perpendicularly to the direction of a uniform magnetic field, i.e. a magnetic field of constant magnitude and direction...
– An atomic accelerator that also directs particles in a spiral with a transverse magnetic field.
- Klystron
A klystron is a specialized linear-beam vacuum tube . Klystrons are used as amplifiers at microwave and radio frequencies to produce both low-power reference signals for superheterodyne radar receivers and to produce high-power carrier waves for communications and the driving force for modern...
– A device for amplifying or generating microwaves with greater precision and control than is available from the magnetron.
- Traveling-wave tube – Another microwave amplifier device, capable of greater bandwidths than a klystron.
- Crossed-field amplifier
A crossed-field amplifier is a specialized vacuum tube, first introduced in the mid-1950s and frequently used as a microwave amplifier in very-high-power transmitters....
– A device combining characteristics of magnetrons and TWTs, resulting in a high-powered, narrow-band amplifier.
- Backward wave oscillator
A backward wave oscillator , also called carcinotron or backward wave tube, is a vacuum tube that is used to generate microwaves up to the terahertz range. It belongs to the traveling-wave tube family...
- A wide-band tunable oscillator, M or O-type
- Free-electron laser – A device for amplifying or generating microwaves, infrared light, UV, and X-Rays.
- Maser
A maser is a device that produces coherent electromagnetic waves through amplification by stimulated emission. Historically, “maser” derives from the original, upper-case acronym MASER, which stands for "Microwave Amplification by Stimulated Emission of Radiation"...
– A device for generating microwaves that produces a very low noise and stable signal, a predecessor of the laser.
- Laser
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of photons. The term "laser" originated as an acronym for Light Amplification by Stimulated Emission of Radiation...
– A device for generating coherent light, an evolution of the maser.
- Sputter deposition
Sputter deposition is a physical vapor deposition method of depositing thin films by sputtering, that is ejecting, material from a "target," that is source, which then deposits onto a "substrate," such as a silicon wafer...
– An important industrial application using the same principle of crossed electric and magnetic fields as cavity balls.
- Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...
- H2S radar
H2S was the first airborne, ground scanning radar system. It was developed in Britain in World War II for the Royal Air Force and was used in various RAF bomber aircraft from 1943 to the 1990s. It was designed to identify targets on the ground for night and all-weather bombing...
- Rad Lab
The Radiation Laboratory, commonly called the Rad Lab, was located at the Massachusetts Institute of Technology in Cambridge, Massachusetts and functioned from October 1940 until December 31, 1945...
- Sir John Turton Randall, FRSE
Sir John Turton Randall, FRS, FRSE, was a British physicist and biophysicist, credited with radical improvement of the cavity magnetron, an essential component of centimetric wavelength radar, which was one of the keys to the Allied victory in the Second World War. It is also the key component of...
- Theodor V. Ionescu
Theodor V. Ionescu, Prof. Dr. Doc. was a Romanian physicist and inventor who made remarkable discoveries in plasma physics, ionosphere physics, ion coupling electrons in dense plasmas, masers, magnetron amplifiers, and Zeeman effects related to controlled nuclear fusion and quantum emission...
- Hans Hollmann
Hans Erich Hollmann was a German electronic specialist who made several breakthroughs in the development of radar....
- Harry Boot
Henry Albert Howard "Harry" Boot was an English physicist who with Sir John Randall and James Sayers developed the cavity magnetron, which was one of the keys to the Allied victory in the Second World War.-Biography:...
- Albert Hull
Albert W. Hull is most remembered for his early invention of the magnetron.-Education and early career:...
- Alan Blumlein
Alan Dower Blumlein was a British electronics engineer, notable for his many inventions in telecommunications, sound recording, stereo, television and radar...
- Bernard Lovell
Sir Alfred Charles Bernard Lovell OBE, FRS is an English physicist and radio astronomer. He was the first Director of Jodrell Bank Observatory, from 1945 to 1980.-Early Life:...
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