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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".
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]
Early experiment demonstrating refraction of microwaves by a paraffin lens by John Ambrose Fleming in 1897. After their discovery many scientists and inventors experimented with transmitting and detecting "Hertzian waves" (it would take almost 20 years for the term "radio" to be universally adopted for this type of electromagnetic radiation). [8]
The discovery of electromagnetic waves in space led to the development of radio in the closing years of the 19th century. The electron as a unit of charge in electrochemistry was posited by G. Johnstone Stoney in 1874, who also coined the term electron in 1894. [ 135 ]
As the gaps made and broke contact, the radio wave was audible as a tone in a crystal set. The telegraph key often directly made and broke the 2000 volt supply. One side of the spark gap was directly connected to the antenna. Receivers with thermionic valves became commonplace before spark-gap transmitters were replaced by continuous wave ...
“The object we’ve discovered is spinning way too slowly to produce radio waves — it’s below the death line,” Hurley-Walker said. “Assuming it’s a magnetar, it shouldn’t be possible ...
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Don't look now, but Earth is being bombarded with mysterious, invisible light. Among the typical array of radio signals and microwaves cast out by distant stars, black holes and other celestial ...