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Radio waves are a type of electromagnetic radiation with the lowest frequencies and the longest wavelengths in the electromagnetic spectrum, typically with frequencies below 300 gigahertz (GHz) and wavelengths greater than 1 millimeter (3⁄64 inch), about the diameter of a grain of rice.
A French ship-to-shore radio station in 1904. The invention of radio communication was preceded by many decades of establishing theoretical underpinnings, discovery and experimental investigation of radio waves, and engineering and technical developments related to their transmission and detection. These developments allowed Guglielmo Marconi ...
History of radio. 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 ...
Radio is the technology of communicating using radio waves. [1][2][3] Radio waves are electromagnetic waves of frequency between 3 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmitter connected to an antenna which radiates oscillating electrical energy, often characterized as a wave.
The High-frequency Active Auroral Research Program (HAARP) is a University of Alaska Fairbanks program which researches the ionosphere – the highest, ionized part of Earth's atmosphere. The most prominent instrument at HAARP is the Ionospheric Research Instrument (IRI), a high-power radio frequency transmitter facility operating in the high ...
Aleksandr Popov (physicist) Alexander Stepanovich Popov (sometimes spelled Popoff; Russian: Александр Степанович Попов; March 16 [O.S. March 4] 1859 – January 13 [O.S. December 31, 1905] 1906) was a Russian physicist who was one of the first people to invent a radio receiving device. [1][2][3] Popov's work as a teacher ...
The history of radar (where radar stands for radio detection and ranging) started with experiments by Heinrich Hertz in the late 19th century that showed that radio waves were reflected by metallic objects. This possibility was suggested in James Clerk Maxwell 's seminal work on electromagnetism.
Radio receiver. A portable battery-powered AM/FM broadcast receiver, used to listen to audio broadcast by local radio stations. A modern communications receiver, used in two-way radio communication stations to talk with remote locations by shortwave radio. Girl listening to vacuum tube console radio in the 1940s.