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Greenleaf Whittier Pickard (February 14, 1877, Portland, Maine - January 8, 1956, Newton, Massachusetts) was a United States radio pioneer. Pickard was a researcher in the early days of wireless. He was responsible for the development of the crystal detector, (cat's whisker detector), a radio wave detector which was the central component in early radio receivers called crystal radios, which were the most widely used radio receivers until about 1920 and continued to be used until World War 2. He also experimented with antennas, radio wave propagation, and noise suppression. On August 30, 1906 he filed a patent for a silicon crystal detector, which was granted on November 20, 1906.〔http://www.bellsystemmemorial.com/belllabs_transistor1.html. 17:42, 15 March 2006.〕 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 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 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 (1807-1892). Pickard was president of the Institute of Radio Engineers 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 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 detector), 1908 * - ''Oscillation detector and rectifier'' ("plated" silicon carbide 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 * - ''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'' 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Greenleaf Whittier Pickard」の詳細全文を読む スポンサード リンク
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