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The first commercial AM Audion vacuum tube radio transmitter, built in 1914 by Lee De Forest who invented the Audion in 1906. During the mid-1920s, amplifying vacuum tubes revolutionized radio receivers and transmitters. John Ambrose Fleming developed a vacuum tube diode. Lee de Forest placed a screen, added a "grid" electrode, creating the triode.
Before the discovery of electromagnetic waves and the development of radio communication, there were many wireless telegraph systems proposed and tested. [4] In April 1872 William Henry Ward received U.S. patent 126,356 for a wireless telegraphy system where he theorized that convection currents in the atmosphere could carry signals like a telegraph wire. [5]
1920s: Radio was first used to transmit pictures visible as television. 1926: Official Egyptian decree to regulate radio transmission stations and radio receivers. [40] Early 1930s: Single sideband (SSB) and frequency modulation (FM) were invented by amateur radio operators. By 1940, they were established commercial modes.
The next year the company used the same concept to begin establishing the first radio network. [107] The WEAF and WJZ chains. At the same time in early 1922 that it announced the beginning of advertisement-supported broadcasting, AT&T also introduced its plans for the development of the first radio network. [104]
1922: J. McWilliams Stone invents the first portable radio receiver. George Frost builds the first "car radio" in his Ford Model T. 1923 The 15-year-old Manfred von Ardenne is granted his first patent for an electron tube having a plurality of electrodes. Siegmund Loewe (1885–1962) builds with the tube his first radio receiver "Loewe Opta-".
In 1983, KDAY-AM became the first radio station to play wall-to-wall rap music, thanks to an ambitious new music director and some soon-to-be famous DJs. When L.A. invented rap radio: The rise of KDAY
Reginald Aubrey Fessenden (October 6, 1866 – July 22, 1932) was a Canadian electrical engineer and inventor who received hundreds of patents in fields related to radio and sonar between 1891 and 1936 (seven of them after his death).
In 1945 on the 50th anniversary of Popov's experiment the old Soviet Union made 7 May a new holiday, Radio Day, the day they claim Popov invented radio. Historians note this holiday may be more due to Cold War era politics than historical evidence. [14] [1] [3] Radio Day is still officially marked in Russia and Bulgaria.