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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.
Radio waves were first predicted by the theory of electromagnetism that was proposed in 1867 by Scottish mathematical physicist James Clerk Maxwell. [5] His mathematical theory, now called Maxwell's equations, predicted that a coupled electric and magnetic field could travel through space as an "electromagnetic wave".
The early history of radio is the history of technology that produces and uses radio instruments that use radio waves. Within the timeline of radio, many people contributed theory and inventions in what became radio. Radio development began as "wireless telegraphy". Later radio history increasingly involves matters of broadcasting.
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.
Although they often faced obstacles and policy limitations, beginning in the early 1900s a few women were able to participate in the pioneering development of radio communication. Anna Nevins began working for United Wireless in 1906 , and is shown here at the station atop the Waldorf-Astoria Hotel in New York City in 1909.
A new type of stellar object has been discovered releasing energetic bursts of radio waves every 22 minutes. An unusual object has been releasing pulses of radio waves in space for decades ...
The first practical radio transmitters and receivers invented in 1894–1895 by Guglielmo Marconi used radiotelegraphy. [5] It continued to be the only type of radio transmission during the first few decades of radio, called the "wireless telegraphy era" up until World War I , when the development of amplitude modulation (AM) radiotelephony ...