In radio communication, used in radio and television broadcasting, cell phones, two-way radios, wireless networking, and satellite communication, among numerous other uses, radio waves are used to carry information across space from a transmitter to a receiver, by modulating the radio signal (impressing an information signal on the radio wave by varying some aspect of the wave) in the transmitter. In radar, used to locate and track objects like aircraft, ships, spacecraft and missiles, a beam of radio waves emitted by a radar transmitter reflects off the target object, and the reflected waves reveal the object's location to a receiver that is typically colocated with the transmitter. In radio navigation systems such as GPS and VOR, a mobile navigation instrument receives radio signals from multiple navigational radio beacons whose position is known, and by precisely measuring the arrival time of the radio waves the receiver can calculate its position on Earth. In wireless radio remote control devices like drones, garage door openers, and keyless entry systems, radio signals transmitted from a controller device control the actions of a remote device. (Full article...)
The National Broadcasting Company's NBC Radio Network (also known as the NBC Red Network from 1927 to 1942) was an American commercial radio network which was in continuous operation from 1926 through 1999. Along with the NBC Blue Network, it was one of the first two nationwide networks established in the United States. Its major competitors were the Columbia Broadcasting System (CBS), founded in 1927, and the Mutual Broadcasting System, founded in 1934. In 1942, NBC was required to divest one of its national networks, so it sold NBC Blue, which was soon renamed the American Broadcasting Company (ABC). After this separation, the Red Network continued as the NBC Radio Network.
For the first 61 years of its existence, this network was owned by the Radio Corporation of America (RCA) with New York City radio station WEAF (renamed WNBC in 1946, WRCA in 1954 and again as WNBC in 1960) as its flagship station. Following the emergence of television as the dominant entertainment medium and much of NBC Radio's talent migrating both to CBS and NBC television, the network made multiple investments in programming in hopes of retaining relevance. These included the weekend program umbrella Monitor (1955–1975), the all-news focused NBC News and Information Service (1975–1977) and the talk radio service NBC Talknet, all of which encountered varying degrees of success and failure. (Full article...)
Image 5Frequency spectrum of a typical modulated AM or FM radio signal. It consists of a component C at the carrier wave frequency with the information (modulation) contained in two narrow bands of frequencies called sidebands (SB) just above and below the carrier frequency. (from Radio)
Image 6Rotating marine radar antenna on a ship (from Radio)
Image 8Neighborhood wireless WAN router on telephone pole (from Radio)
Image 9Animated diagram of a half-wave dipole antenna receiving a radio wave. The antenna consists of two metal rods connected to a receiver R. The electric field (E, green arrows) of the incoming wave pushes the electrons in the rods back and forth, charging the ends alternately positive (+) and negative (−). Since the length of the antenna is one half the wavelength of the wave, the oscillating field induces standing waves of voltage (V, represented by red band) and current in the rods. The oscillating currents (black arrows) flow down the transmission line and through the receiver (represented by the resistance R). (from Radio wave)
Image 11Around 1920, radio broadcasting started to get popular. The Brox Sisters, a popular singing group, gathered around the radio at the time. (from History of radio)
Image 13Animation of a half-wave dipoleantenna radiating radio waves, showing the electric field lines. The antenna in the center is two vertical metal rods connected to a radio transmitter (not shown). The transmitter applies an alternating electric current to the rods, which charges them alternately positive (+) and negative (−). Loops of electric field leave the antenna and travel away at the speed of light; these are the radio waves. In this animation the action is shown slowed down tremendously. (from Radio wave)
Image 16In the 1920s, the United States government publication, "Construction and Operation of a Simple Homemade Radio Receiving Outfit", showed how almost any person handy with simple tools could a build an effective crystal radio receiver. (from History of radio)
Image 18British Post Office engineers inspect Guglielmo Marconi's wireless telegraphy (radio) equipment in 1897. (from History of radio)
Image 19Radio communication. Information such as sound is converted by a transducer such as a microphone to an electrical signal, which modulates a radio wave produced by the transmitter. A receiver intercepts the radio wave and extracts the information-bearing modulation signal, which is converted back to a human usable form with another transducer such as a loudspeaker. (from Radio)
Image 24Donald Manson working as an employee of the Marconi Company (England, 1906) (from History of radio)
Image 25Diagram of the electric fields (E) and magnetic fields (H) of radio waves emitted by a monopole radio transmitting antenna (small dark vertical line in the center). The E and H fields are perpendicular, as implied by the phase diagram in the lower right. (from Radio wave)
Image 26Motorola SCR-536 from WW2, the first walkie-talkie (from Radio)
Image 27Advertisement placed on November 5, 1919, Nieuwe Rotterdamsche Courant announcing PCGG's debut broadcast scheduled for the next evening (from Radio broadcasting)
Image 28Heinrich Rudolf Hertz (1856–1894) proved the existence of electromagnetic radiation (from History of radio)
... that two state representatives got into a fight in the parking lot of Miami's Radio Mambí after one's father insulted the other's on the air?
... that X-radiographs of Jan Lievens's circa 1629–1630 Self-Portrait showed that the artist made "transformative revisions to his appearance" in the portrait?
RadioDecember 12, 2006 "...to create, expand, and maintain Wikipedia articles related to radio, including radio propagation and reception, radio programming, radio personalities, and the business of radio." (Example: Mutual Broadcasting System)
Radio StationsFebruary 15, 2005 "...to coordinate the activities of creating and maintaining articles about radio stations." (Example: Pulse FM Kingborough & Huon)
PodcastingJanuary 21, 2007 "...to make Wikipedia's knowledge of notable Podcast and podcast-related information as complete as possible." (Example: Podcast)
Amateur Radio(Inactive), August 24, 2006 "...to improve Wikipedia's articles related to Amateur radio, maintain the amateur radio category and its sub-categories for clean organization, and to produce and maintain templates for Amateur radio-related topic identification." (Example: Amateur radio)
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