Karl Ferdinand Braun (German: [ˈfɛʁdinant ˈbʁaʊ̯n] ; 6 June 1850 – 20 April 1918) was a German applied physicist who shared the 1909 Nobel Prize in Physics with Guglielmo Marconi for their contributions to the development of radio. With his two circuit system, long range radio transmissions and modern telecommunications were made possible. His invention of the phased array antenna in 1905 led to the development of radar, smart antennas, and MIMO. Braun built the first cathode-ray tube in 1897, which led to the development of television, and the first semiconductor diode in 1874, which co-started the development of electronics and electronic engineering. Braun was a co-founder of Telefunken, one of the pioneering communications and television companies. He has been called the "father of television" (shared with inventors like Paul Nipkow), the "great-grandfather of every semiconductor ever manufactured," and a co-father of radiotelegraphy, together with Marconi, laying the foundation for all modern wireless systems.
Biography
Education and career
Karl Ferdinand Braun was born on 6 June 1850 in Fulda. In 1868, Braun started studying physics, chemistry, and mathematics at the University of Marburg. The following year, he transferred to the University of Berlin and became an assistant to Heinrich Gustav Magnus. After Magnus' death in 1870, Braun continued his training with Georg Hermann Quincke. In 1872, he received his Ph.D. with a thesis on vibrating strings, and subsequently followed Quincke to the University of Würzburg as an assistant. In 1874, Braun accepted a teaching appointment at the Thomasschule in Leipzig. In 1876, he returned to the University of Marburg as Extraordinary Professor of Theoretical Physics, and in 1880 was invited to fill a similar post at the University of Strassburg. He was made Professor of Physics at the Karlsruhe Institute of Technology in 1883, and was invited by the University of Tübingen in 1885. In 1895, he returned to Strassburg as Principal of the Physics Institute.
Radio work In 1897, Braun joined the line of wireless pioneers. His major contributions to the development of radio were the introduction of a closed tuned circuit in the generating part of the transmitter, 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 detector . Wireless telegraphy claimed his full attention in 1898, and for many years after that he applied himself almost exclusively to the task of solving its problems. He had written extensively on wireless subjects and was well known through his many contributions to The Electrician and other scientific journals. In 1899, he applied for the patent Wireless electro transmission of signals over surfaces. Also in 1899, he is said to have applied for a patent on Electro telegraphy by means of condensers and induction coils. Pioneers working on wireless devices eventually came to a limit of distance they could cover; connecting the antenna directly to the spark gap produced only a heavily damped pulse train. There were only a few cycles before oscillations ceased. 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 1905, Braun invented the phased array antenna; he described in his Nobel Prize lecture how he carefully arranged three antennas to transmit a directional signal. This invention led to the development of radar, smart antennas, and MIMO. Braun's British patent on tuning was used by Guglielmo Marconi in many of his tuning patents. Marconi used Braun's patents (among others). Marconi would later admit to Braun himself that he had "borrowed" portions of Braun's work. In 1909, Braun and Marconi were jointly awarded the Nobel Prize in Physics "in recognition of their contributions to the development of wireless telegraphy"; the prize awarded to Braun depicts this design. He experimented initially at the University of Strassburg, not long before he bridged a distance of 42 km to Mutzig. In spring 1899, Braun, accompanied by his colleagues Cantor and Zenneck, went to Cuxhaven to continue their experiments at the North Sea. On 24 September 1900, radio telegraphy signals were exchanged regularly with the island of Heligoland over a distance of 62 km. Light vessels in the river Elbe and a coast station at Cuxhaven commenced a regular radio telegraph service.
Later life and death In 1914, Braun went to New York in the United States to be a witness for the defense in a lawsuit regarding a patent claim by the Marconi Company against Telefunken's wireless station in Sayville. He was a Lutheran. After the U.S. declared war on Germany in 1917, Braun was detained as an enemy alien. He was allowed to move freely within Brooklyn, where he died of a heart attack the following year on 20 April at the age of 67.
Inventions and discoveries
Semiconductor In 1874, Braun discovered the asymmetric conduction properties of certain materials, which became the foundation for the point-contact rectifier. This discovery showed that certain metal-semiconductor junctions could conduct electricity more easily in one direction than the other, a crucial property for diodes. Braun's work with semiconductors led to the development of the first point-contact diode, often credited as a basic semiconductor device that allowed the rectification of alternating current into direct current. This is important because it was one of the first real-world applications of semiconducting materials, paving the way for future semiconductor devices that would later evolve into modern diodes, transistors, and other semiconductor technology. Braun's discoveries were instrumental in the early development of electronics and helped lay the groundwork for the semiconductor industry we know today.
Cathode-ray tube
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