The German physicist Ferdinand Braun (1850-1918) received the Nobel Prize in Physics for his work on wireless telegraphy.

Karl Ferdinand Braun was born in Fulda, Germany, on June 6, 1850, the son of Konrad and Franziska (Gohring) Braun. Upon graduation from his local gymnasium, he entered the University of Marburg, later completing his Ph.D. at the University of Berlin in 1872 with a dissertation on the vibrations of elastic rods and strings.

Braun's career began at the University of Würzburg in 1872, where he worked as assistant to George Hermann Quincke, the eminent German physicist and authority on elastic vibrations--of which light (electromagnetic radiation) was thought to be a species. Braun remained with Quincke two years, publishing in 1874 the results of his research on mineral metal sulfides. He discovered that these crystals would conduct electrical currents in one direction only. This finding was important in electrical research and in measuring another property of substances, electrical conductivity. However, there were no immediate practical applications, and not until the early 20th century was the phenomenon employed in crystal radio receivers.

Braun next took a lectureship at the St. Thomas Gymnasium in Leipzig, a post he also held for two years. Then, from 1876 to 1880 he was extraordinary professor at the University of Marburg, his alma mater. In 1880 his itinerant career took him outside of Germany, to the University of Strasbourg in France, where he remained for three years engaged in research, leaving in 1883; he returned again in 1895 as professor of physics and director of the physics institute. In the intervening years, however, he worked in Germany. For three years he was professor of physics at the Technical High School in Karlsruhe, and in the year he left (1885), he also married Amelie Bühler; they had two sons and two daughters. This must have domesticated him, for he remained at his next job, in Tübingen, for ten years, helping to found the Physical Institute there.

After 1890 Braun produced much of the work for which he was later to become famous. Here, his skill as an inventor combined with his grasp of theoretical principles to effect two significant technological achievements--the coupled transmitter and coupled receiver for improved wireless performance (1899 patent) and the cathode-ray oscilloscope (1897).

Braun was attracted to the study of wireless transmission by the question of why it was so difficult to increase the range of transmission to more than 15 kilometers. Though he expected to extend the range of transmission through a mere increase in the production of the transmitter's power, his experience with Hertz oscillators proved that any attempt to increase the power output by increasing the length of the spark gap would find a limit beyond which the power output would only decrease. Braun found his answer in the creation of a sparkless antenna circuit--power from the transmitter was magnetically coupled through the transformer effect to an antenna circuit rather than directly linking it to the power circuit. Related to this work and complementing it was his investigation of aspects of radiotelegraphy, including directional transmission of electromagnetic waves, work on crystal detectors, and use of radio transmissions as beacons for navigation. For these achievements Braun received with Guglielmo Marconi of Italy in 1909 a Nobel Prize for his contributions to wireless telegraphy.

Braun also introduced the first oscilloscope by the use of alternating voltage to shift an electron beam (as it was later understood) within a cathode tube. The trace remaining on the tube's surface corresponded to the amplitude and frequency of the alternating-current voltage. Braun then made use of a rotating mirror to graph the trace he had produced. This invention proved to be an essential instrument in subsequent electronic research.

Despite his great achievements--in fact because of them--Braun's final years were not happy ones. In early 1915, only a few months after the outbreak of World War I, he travelled to the United States to testify on behalf of the Telefunken Co. in litigation involving radio broadcasting. There he remained until the United States entered the war, when it became impossible for him to leave. Though he lived with his son Konrad in New York City, which must have provided some comfort, he was unable to pursue his scientific interests. Deprived of a laboratory, and with little independent means, he spent his last years in inactivity, dying in Brooklyn on April 20, 1918.

Further Reading

• Biographical information on Braun can be gleaned from several sources. Most extensive is the Dictionary of Scientific Biography, vol. II, Charles Gillispie, editor (1973). Also helpful is Who's Who in Science: Antiquity to Present, 1st. ed., edited by Allen G. Debus (1968). There is Heathcote, Nobel Winners in Physics, 1901-1950 (1953), but it contains little information on Braun's life.
• Kurylo, Friedrich, Ferdinand Braun, a life of the Nobel prizewinner and inventor of the cathode-ray oscilloscope, Cambridge, Mass.: MIT Press, 1981.