Greenleaf Whittier Pickard
Encyclopedia
Greenleaf Whittier Pickard (February 14, 1877, Portland, Maine
Portland, Maine
Portland is the largest city in Maine and is the county seat of Cumberland County. The 2010 city population was 66,194, growing 3 percent since the census of 2000...


- January 8, 1956, Newton, Massachusetts
Newton, Massachusetts
Newton is a city in Middlesex County, Massachusetts, United States bordered to the east by Boston. According to the 2010 U.S. Census, the population of Newton was 85,146, making it the eleventh largest city in the state.-Villages:...

) was a United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 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...

 pioneer. Pickard was a researcher in the early days 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...

. He experimented with crystal detectors, antennas, wave propagation, and noise suppression. Crystal detectors are used in crystal radio receiver
Crystal radio receiver
thumb|Boy listening to a modern crystal radioA crystal radio receiver, also called a crystal set or cat's whisker receiver, is a very simple radio receiver, popular in the early days of radio. It needs no battery or power source and runs on the power received from radio waves by a long wire antenna...

s and loop antennas used with many types of receivers.
On August 30, 1906 he filed a patent for a silicon
Silicon
Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...

 crystal
Crystal
A crystal or crystalline solid is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions. The scientific study of crystals and crystal formation is known as crystallography...

 detector, which was granted on November 20, 1906. Pickard's detector was revolutionary in that he found that a fine pointed wire known as a "cat's whisker", in delicate contact with a mineral produced the best semiconductor
Semiconductor
A semiconductor is a material with electrical conductivity due to electron flow intermediate in magnitude between that of a conductor and an insulator. This means a conductivity roughly in the range of 103 to 10−8 siemens per centimeter...

 effect.
On June 10, 1907, he filed a patent for a Magnetic Aerial (a loop aerial) which was granted on January 21, 1908. Pickard's loop antenna was revolutionary in that he found that it had directional properties that could be used to reduce interference to the intended wireless communications. Greenleaf Whittier Pickard was named after his great-uncle, the American Quaker John Greenleaf Whittier
John Greenleaf Whittier
John Greenleaf Whittier was an influential American Quaker poet and ardent advocate of the abolition of slavery in the United States. He is usually listed as one of the Fireside Poets...

 (1807-1892). Pickard was president of the Institute of Radio Engineers
Institute of Radio Engineers
The Institute of Radio Engineers was a professional organization which existed from 1912 until January 1, 1963, when it merged with the American Institute of Electrical Engineers to form the Institute of Electrical and Electronics Engineers .-Founding:Following several attempts to form a...

in 1913.
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