Greenleaf Whittier Pickard (February 14, 1877,

Portland, Maine Portland is the largest city in the U.S. state of Maine and the seat of Cumberland County. Portland's population was 68,408 in April 2020. The Greater Portland metropolitan area is home to over half a million people, the 104th-largest metropo ...

– January 8, 1956,

Newton, Massachusetts Newton is a city in Middlesex County, Massachusetts, United States. It is approximately west of downtown Boston. Newton resembles a patchwork of thirteen villages, without a city center. According to the 2020 U.S. Census, the population of ...

) was a

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...

radio Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a tr ...

pioneer. Pickard was a researcher in the early days of

wireless Wireless communication (or just wireless, when the context allows) is the transfer of information between two or more points without the use of an electrical conductor, optical fiber or other continuous guided medium for the transfer. The most ...

. While not the earliest discoverer of the rectifying properties of contact between certain solid materials, he was largely responsible and most famous for the development of the

crystal detector A crystal detector is an obsolete electronic component used in some early 20th century radio receivers that consists of a piece of crystalline mineral which rectifies the alternating current radio signal. It was employed as a detector (dem ...

, the earliest type of diode detector.G. W. Pickard, "How I Invented the Crystal Detector". ''Electrical Experimenter'', vol. VII, no. 4, p. 325, Aug. 1919
/ref> The crystal detector was the central component in many early

radio receiver In radio communications, a radio receiver, also known as a receiver, a wireless, or simply a radio, is an electronic device that receives radio waves and converts the information carried by them to a usable form. It is used with an antenna. Th ...

s from around 1906 until about 1920. Pickard also experimented with antennas, radio wave propagation and noise suppression. On August 30, 1906 he filed a patent for a

silicon Silicon is a chemical element with the symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic ...

crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macro ...

detector, which was granted on November 20, 1906. 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 had directional properties that could be used to reduce interference to the intended wireless communications. On June 21, 1911 he filed a patent on a crystal detector incorporating a springy low inertia wire of about 24 gauge formed with a loop or helix and pointed to make contact with the crystal. Crystal detectors incorporating this construction would become the most widely used and popularly known by the term ''cat whisker detector''. This patent was granted on July 21, 1914. Greenleaf Whittier Pickard was named after his great-uncle, the American Quaker

John Greenleaf Whittier John Greenleaf Whittier (December 17, 1807 – September 7, 1892) was an American Quaker poet and advocate of the abolition of slavery in the United States. Frequently listed as one of the fireside poets, he was influenced by the Scottish poet ...

(1807-1892). Pickard was president of the

Institute of Radio Engineers The Institute of Radio Engineers (IRE) was a professional organization which existed from 1912 until December 31, 1962. On January 1, 1963, it merged with the American Institute of Electrical Engineers (AIEE) to form the Institute of Electrical ...

in 1913.

Patents

* - ''Electrostatic separation'' * - ''Electrostatic separation'' * - ''Electrostatic separation'' * - ''Electrostatic separation'' * - ''Means for receiving intelligence communicated by electric waves'' (silicon detector), 1906 * - ''Electrostatic separator'', 1907 * - ''Means for receiving intelligence communicated by electric waves'' (

copper sulfate Copper sulfate may refer to: * Copper(II) sulfate, CuSO4, a common compound used as a fungicide and herbicide * Copper(I) sulfate Copper(I) sulfate, also known as cuprous sulfate, is an inorganic compound with the chemical formula Cu2 SO4. It ...

solution detector), 1907 * - ''Intelligence intercommunication by magnetic wave component'' (loop antenna), 1908 * - ''Means for receiving intelligence communicated by electric waves'' (spring-loaded detector contact), 1908 * - ''Oscillation receiver'' (fused zinc oxide detector), 1908 * - ''Oscillation receiver'' (polished silicon detector, 1908 * - ''Oscillation detecting means'' (

molybdenite Molybdenite is a mineral of molybdenum disulfide, Mo S2. Similar in appearance and feel to graphite, molybdenite has a lubricating effect that is a consequence of its layered structure. The atomic structure consists of a sheet of molybdenum ato ...

detector), 1908 * - ''Oscillation detector and rectifier'' ("plated"

silicon carbide Silicon carbide (SiC), also known as carborundum (), is a hard chemical compound containing silicon and carbon. A semiconductor, it occurs in nature as the extremely rare mineral moissanite, but has been mass-produced as a powder and crystal s ...

detector with DC bias), G.W. Pickard, 1909 * - ''Oscillation receiver'' (fractured surface red zinc oxide ( zincite) detector), 1909 * - ''Oscillation device'' (iron pyrite detector), 1909 * - ''Electrical Space Communication'' (interference mitigation), 1909 * - ''Telephone receiving apparatus'' (protective piece and adjustable diaphragm distance), 1910 * - ''Detector for wireless telegraphy and telephony'' (looped or humped springy wire detector contact), 1914 * - ''Oscillation detectors'' (pairs of minerals), 1914 * - ''Valve detector for wireless'' (vacuum tube with conducting shield to drain static), 1915 * - ''Receiver for wireless telephony and telegraphy'' (interrupted or switched circuit instead of rectifier), 1916 * - ''Means for receiving intelligence communicated by electric waves'' (receiving circuit, divided from #836531), 1917 * - ''Optical selection of split mica sheets'' * - ''Distinguishing dielectric sheets'' * - ''Electrical reactance and method and apparatus'' * - ''Radio Receiving Apparatus'' (multiple loop antennas), 1920 * - ''Extreme loading condenser'' ''Reissued'' * - ''Means for receiving intelligence communicated by electric waves''

References

;Citations {{DEFAULTSORT:Pickard, Greenleaf Whittier Radio pioneers IEEE Medal of Honor recipients People from Portland, Maine 1877 births 1956 deaths