1900 to 1920: North American and European Technology

The passage of electrical current from a heated filament to a metal plate, called Thomas Edison Effect, was studied by English engineer John Fleming, Maxwell student and Marconi consultant. In 1904 he made the first thermionic tube, a diode with electrons flowing in only one direction. The name “tube” has its origin by the electric current control, similar to a hydraulic tube.


Lee De Forest em 1915

Lee De Forest, North American researcher, put a grid on Fleming tube, creating, in 1907, the triode tube, amplifying the received signals many times. Forest’s tube, called Audion, is the radio tubes’ base.

In the middle of 1906, a friend of Forest made a device to reproduce a brighter light in a kerosene lantern, called Radiolite.

Forest was looking for a name to his equipment, not happy about wireless, because it was a negative name and it was not able to be properly translated to other languages. Impressed by Radiolite, he approved radio, from “radiant” (in all directions) and also because of the reference to a grower and his seeds. From this last one, came the name broadcasting, “hand sowing”.

In July, 18, 1907, on board of Thelma yatch, Forest transmitted songs and voices, considered by many people, the first broadcasting show. He transmitted, in 1910, an Enrico Caruso performance, at the Metropolitan Opera, in other to make the new way popular. At that time, transmission was reduced to a few receivers.

The night before Christmas, in 1906, in the state of Massachusetts, United States, Reginald Fessenden produces a broadcasting radio “show”, with announcement and music.

The greatest radio circuit creator, the North American Edwin Armstrong, was responsible for the Regenerative Circuit, in 1912, and for the Super Heterodyne Circuit development (1918), as it’s used on the radio so far.


Receptor regenerativo de Armstrong, 1912

Armstrong also created the Frequency Modulation – FM (1933), broadcasted in the year of 1939, in Alpine, New Jersey.

At 6 p.m. on November 2, 1920, some men, directed by Frank Conrad, changed the history’s way. In a stadium, KDKA, the first licensed radio station, starts commercial radio broadcasting, in Pittsburgh, USA. The radio station, property of Westinghouse, transmitted the Harding versus Cox election on the presidential race.  

As it happened with the radio invention, the polemic continues: Argentineans claims the first show transmission to be theirs. In August, 27, 1920, in the Coliseo Theater, in Buenos Aires, Sociedad Radio Argentina transmitted Richard Wagner opera, the Parsifal.






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