Karl Ferdinand Braun

For those of a similar name, see Carl Braun.

Karl Ferdinand Braun
Born	(1850-06-06)6 June 1850 Fulda, Electorate of Hessen, Germany
Died	Brooklyn, New York, U.S.
Nationality	German
Fields	Physics
Institutions	University of Karlsruhe, University of Marburg, University of Strassburg, University of Tübingen, University of Würzburg
Alma mater	University of Marburg, University of Berlin
Doctoral advisor	A. Kundt, G. H. Quincke
Doctoral students	L. I. Mandelshtam, A. Schweizer
Known for	Cathode ray tube, Cat's whisker diode
Notable awards	Nobel Prize in Physics (1909)

24 September 1900: Bargman, Braun and telegraphist at wireless station Helgoland

Karl Ferdinand Braun (6 June 1850 – 20 April 1918) was a German inventor, physicist and Nobel laureate in physics. Braun contributed significantly to the development of radio and television technology: he shared with Guglielmo Marconi the 1909 Nobel Prize in Physics.

Biography

Braun was born in Fulda, Germany, and educated at the University of Marburg and received a Ph.D. from the University of Berlin in 1872. In 1874 he discovered that a point-contact semiconductor rectifies alternating current. He became director of the Physical Institute and professor of physics at the University of Strassburg in 1895.

In 1897 he built the first cathode-ray tube (CRT) and cathode ray tube oscilloscope. CRT became the cornerstone in developing fully electronic television. In the early 21-st century the CRT technology started to be replaced by flat screen technologies (such as liquid crystal display (LCD), light emitting diode (LED) and plasma displays) on television sets and computer monitors. The CRT is still called the "Braun tube" in German-speaking countries (Braunsche Röhre) and in Japan (ブラウン管: Buraun-kan).

During the development of radio, he also worked on wireless telegraphy. In 1897 Braun joined the line of wireless pioneers. 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. Wireless telegraphy claimed Dr. Braun's full attention in 1898, and for many years after that he applied himself almost exclusively to the task of solving its problems. Dr. Braun had written extensively on wireless subjects and was well known through his many contributions to the Electrician and other scientific journals. In 1899, he would apply for the patents, Electro telegraphy by means of condensers and induction coils and Wireless electro transmission of signals over surfaces.

Around 1898, he invented a crystal diode rectifier or cat's whisker diode. 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.

Braun invented the phased array antenna in 1905. 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 Marconi in many of his tuning patents. Guglielmo 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 shared the Nobel Prize for physics with Marconi for "contributions to the development of wireless telegraphy." The prize awarded to Braun in 1909 depicts this design. Braun experimented at first at the University of Strasbourg. Not before long he bridged a distance of 42 km to the city of 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. Lightvessels in the river Elbe and a coast station at Cuxhaven commenced a regular radio telegraph service.

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 detained, but could move freely within Brooklyn, New York. Braun died in his house in Brooklyn, before the war ended in 1918.

SID Karl Ferdinand Braun Prize

In 1987 the Society for Information Display created the Karl Ferdinand Braun Prize, awarded for an outstanding technical achievement in display technology.

Patents

• U.S. Patent 0,750,429, Wireless Electric Transmission of Signals Over Surfaces
• U.S. Patent 0,763,345, Means for Tuning and Adjusting Electric Circuits

See also

• History of radio
• Invention of radio
• Edouard Branly

References

Footnotes

• In the anime adaptation of the 2009 Japanese visual novel, Steins;Gate, the character Yūgo Tennōji, a.k.a. 'Mr. Braun', uses the pseudonym 'FB', after Karl Ferdinand Braun.

General

• K.F. Braun: "On the current conduction in metal sulphides (title translated from German into English)", Ann. Phys. Chem., 153 (1874), 556. (In German) An English translation can be found in "Semiconductor Devices: Pioneering Papers", edited by S.M. Sze, World Scientific, Singapore, 1991, pp. 377–380.
• Keller, Peter A.: The cathode-ray tube: technology, history, and applications. New York: Palisades Press, 1991. ISBN 0-9631559-0-3.
• Keller, Peter A.: "The 100th Anniversary of the Cathode-Ray Tube," Information Display, Vol. 13, No. 10, 1997, pp. 28–32.
• F. Kurylo: "Ferdinand Braun Leben und Wirken des Erfinders der Braunschen Röhre Nobelpreis 1909", München: Moos Verlag, 1965. (In German)

External links

• Karl Ferdinand Braun at the Mathematics Genealogy Project
• "Ferdinand Braun – Biography". Nobel Lectures. Physics 1901-1921, Elsevier Publishing Company, Amsterdam, 1967.
• Naughton, Russell, "Karl Ferdinand Braun, Dr : 1850 - 1918".
• "Karl Ferdinand Braun ". Biographies of Famous Electrochemists and Physicists Contributed to Understanding of Electricity.
• "Karl Ferdinand Braun, 1850-1918". (German) (English translation)
• The Ferdinand-Braun-Institut fuer Hoechstfrequenztechnik Berlin, Germany
• Alfred Thomas Story A Story of Wireless Telegraphy. D. Appleton and company 1904