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Braun, KF

Karl Ferdinand Braun

Achievements: Oscilliscope. Radio.

Born: June 6, 1850; Fulda, Hesse-Kassel, Prussia (now Germany)

Died: April 20, 1918; Brooklyn, NY (Aged 67)

Field & Discipline: Science; Physics; Physicist

Language: German

Father: Konrad Braun

Mother: Franziska Gohring

Siblings: Unknown

Spouse: Amelie Buhler (m. 1885)

Children: Two sons; two daughters

Education: Fulda Gymnasium; University of Marburg (1867-69); University of

Berlin (1869-72)

Major Work:

“Wireless Telegraphy Through Water and Air” (1901)

Life & Times:

Karl Ferdinand Braun wrote a dissertation on the vibration of elastic rods and strings, and received his Ph.D. in 1872. After two years as an assistant at Wurzburg University, Braun spent two further years (1874-76) as headmaster of the St. Thomas Gymnasium in Leipzig.

In 1874, Braun published his discovery that crystals of mineral metal sulfides, such as galena and pyrite, act as rectifiers, conducting electric currents in only one direction. Although his discovery did not find an immediate application, this came about 50 years later when the principles he discovered were employed in the crystal rectifiers ("cat's whiskers") used in the crystal radio receivers of the early 20th century.

In 1876 Braun returned to Marburg as professor of theoretical physics. In 1880 he went to the University of Strasbourg, where as professor of theoretical physics he lectured on electrostatics, magnetism, galvanism, and thermoelectrity. In 1883 he moved on to the Technical High School at Karlsruhe, as professor of physics.

In 1885 he transferred to the University of Tubingen (his place at Karlsruhe being filled by [was succeeded by] Hertz*), as professor of experimental physics, and directed the creation of the new Physics Institute. In 1895 Braun returned to settle at the University of Strasbourg as professor of physics and director of the Physics Institute.

In 1897 Braun invented and published a paper on the Braun tube, or oscilloscope, which gave a picture of the oscillations of high-frequency alternating currents. In his [invented] oscilloscope* - an adaptation of the [developed] cathode-ray tube* invented by [adapted invention of] Crookes* in 1878, Braun used an alternating electromagnetic current to move a fixed beam of electrons within an evacuated cathode-ray tube, the trace of which - as a linear wave pattern made by the currents fluctuations on the flouorescent surface (or screen) of the tube - could be graphed by means of a rotating mirror, thus making the controlled flow of voltage visible.

The Braun tube became a valuable laboratory instrument – most immediately aiding the work at Kiel of the German physicist [his work related to] Lenard* on cathode rays (electron rays produced in a vacuum) - and was the forerunner of more sophisticated oscilloscopes which became essential tools in electrical research and technology, including modern television, video and radar display tubes.

In the late 1890s Braun also began to study radio transmission, inspired by the Italian electrical engineer [inspired by] Marconi's*1896 patent for a radio transmitter that had a broadcasting range of eight to twelve miles. Braun was puzzled by Marconi's difficulties in increasing the range of his transmitter, which he believed should be possible by increasing its electrical power.

His investigations, aided by his oscilloscope, revealed that there was an upper limit to the efficiency of a particular component in the antenna of the system of the Marconi transmitter, known as the Hertz oscillator. This was an electric sparking apparatus used to generate Hertzian waves (periodic oscillations) that travel through the air and, up to a point, both Marconi and Braun had found that increasing the size of the "spark gap" increased the range of transmission. However, Braun discovered that when the spark gap exceeded a certain size, waves were produced that interfered with one another, and weakened transmission.

By 1898, Braun had developed a transmitter using a sparkless antenna (aerial) circuit, in which the power from the transmitter was magnetically coupled (using electromagnetic induction - huge wire coils, or condensers, that converted the electricity into magnetic fields) indirectly to the antenna circuit, instead of the antenna being connected directly to

the power circuit.

This invention greatly increased the broadcasting range of a radio transmitter, and this practice of isolating the antenna from the transmitter circuit (the principle of magnetic coupling) has been applied to all later transmission technologies, for radio, radar, television and other wireless media.

Braun also redesigned the radio receiver so that it, too, operated with condensers, but used direct coupling between the condenser circuit and the aerial. In this way, through resonance the oscillations from the transmitting station produced the maximum effect at the receiving station, with the added advantage that the waves at the receiving station were of the same period as those emitted by the transmitter (tuned to the same frequency). As a result, it was possible to select the frequency to which the receiver responded so that it was not affected by signals of different frequencies from other transmitters.

Braun took out a patent for his sparkless invention (known as the Braun transmitter) in 1899 and founded a company, Professor Braun's Telegraph Company, to market later inventions. Among these was his unidirectional broadcasting antenna and his crystal detector (a forerunner of the transistor, invented in 1947 by [anticipated] Shockley*, [anticipated] Bardeen* and [anticipated] Brattain* at the Bell Telephone Laboratories), a great advance over the [improved the coherer of] (Branly-)Lodge* coherer used by Marconi.

In 1901 Braun published an important set of papers on wireless telegraphy titled “Wireless Telegrahy Through Water and Air,” and the following year he demonstrated the first functional transmission and reception of directional wireless communication, using a directional transmitter and a directional receiver.

In 1909, because his work on Marconi's transmitter made radio practical for telecommunications, Braun shared with Marconi the Nobel Prize for Physics for the invention of "wireless telegraphy,” and in 1914, he travelled to New York City in order to testify in a patent litigation concerning radio broadcasting. :Legal delays and intermittent ill health kept him in New York until 1917, when the United States entered World War I.

As a German Braun was detained in the U.S., and died in a Brooklyn hospital.

Extra Connections: His work related to that of [work related to] Swinton* , [work related to] Zworykin*, [work related to] JL Baird* and [work related to] Watson-Watt*

His was a major contribution to the development of [key developer of] TV*

Assessment: Ferdinand Braun was a German theoretical physicist whose research into the behaviour of electricity led him to produce several ground-breaking applications..

Oneliner: Ferdinand Braun, inventor of the oscilloscope

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