Karl Ferdinand Braun (6 juin 1850 - 20 avril 1918) était un physicien et inventeur allemand, prix Nobel de physique. Braun a contribué de façon notable au développement de la radio et de la télévision de la technologie. En 1897, il construit le premier tube cathodique (CR
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Karl Ferdinand Braun (June 6, 1850 - April 20, 1918) was a German inventor, physicist and Nobel laureate in physics. Braun contributed significantly to the development of the radio and television technology. In 1897 he built the first cathode-ray tube (CRT) and cathode ray tube oscilloscope. During the development of radio, he also worked on wireless telegraphy. His 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. Around 1898, he invented a crystal diode rectifier or cat's whisker diode. Braun's circuit afforded a much longer sustained oscillation because the energy encountered less losses swinging between coil and Leyden Jars. And by means of inductive antenna coupling the radiator was better matched to the generator. The resultant stronger and less bandwidth consuming signals bridged a much longer distance. In 1909 Braun shared the Nobel Prize for physics with Marconi for "contributions to the development of wireless telegraphy." Braun went to the United States at the beginning of World War I (before the U.S. had entered the war) to help defend the German wireless station at Sayville, New York, against attacks by the British-controlled Marconi Corporation. After the US entered the war, Braun was being detained, but could move freely within Brooklyn, New York. Braun died in his house in Brooklyn, before the war ended in 1918. He was 67 years old.
