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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]
In early radio, and to a limited extent much later, the transmission signal of the radio station was specified in meters, referring to the wavelength, the length of the radio wave. This is the origin of the terms long wave , medium wave , and short wave radio. [ 51 ]
A spark-gap transmitter for generating radio frequency electromagnetic waves. Such devices served as the transmitters for most early wireless systems. 24 December 1906: Reginald Fessenden uses an Alexanderson alternator and rotary spark-gap transmitter to make the first radio audio broadcast, from Brant Rock, Massachusetts.
Jansky and his rotating directional radio antenna (early 1930s), the world's first radio telescope. At Bell Telephone Laboratories, Jansky built a directional antenna designed to receive radio waves at a frequency of 20.5 MHz (wavelength about 14.6 meters). It had a diameter of approximately 100 ft. (30 meters) and stood 20 ft. (6 meters) tall.
Drawing of Popov's radio wave based lightning detector Along with his teaching duties at the naval school, Popov pursued related areas of research. Trying to solve a problem with the failure in the electrical wire insulation on steel ships (which turned out to be a problem with electrical resonance ) led him to further explore oscillations of ...
Mysterious fast radio bursts, or millisecond-long bright flashes of radio waves from space, have intrigued astronomers since the first detection of the phenomenon in 2007. The enigmatic signals ...
Scientists have tracked an intense radio signal coming from deep in space to its origin – and been left shocked by what they found.. For years, researchers have been looking to explain fast ...
A new type of stellar object has been discovered releasing energetic bursts of radio waves every 22 minutes. ... pulses of radio waves in space for decades. ... an object 15,000 light-years from ...