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...)
Under Federal Communications Commission (FCC) regulations, a local marketing agreement must give the company operating the station (the "senior" partner) under the agreement control over the entire facilities of the station, including the finances, personnel and programming of the station. Its original licensee (the "junior" partner) still remains legally responsible for the station and its operations, such as compliance with relevant regulations regarding content. Occasionally, a "local marketing agreement" may refer to the sharing or contracting of only certain functions, in particular advertising sales. This may also be referred to as a time brokerage agreement (TBA), local sales agreement (LSA), management services agreement (MSA), or most commonly, a joint sales agreement (JSA) or shared services agreement (SSA). JSAs are counted toward ownership caps for television and radio stations. In Canada, local marketing agreements between domestic stations require the consent of the Canadian Radio-television and Telecommunications Commission (CRTC), although Rogers Media has used a similar arrangement to control a U.S.-based radio station in a border market. (Full article...)
The following are images from various radio-related articles on Wikipedia.
Image 1Radio 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 2Advertisement placed on November 5, 1919 in the Nieuwe Rotterdamsche Courant, announcing PCGG's debut broadcast scheduled for the next evening. (from Radio broadcasting)
Image 3Motorola SCR-536 from WW2, the first walkie-talkie (from Radio)
Image 5Animated 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 results in oscillation of the electrons in the rods, 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 6Animation 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 7Comparison of AM and FM modulated radio waves (from Radio)
Image 8In 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 9Frequency 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 20Around 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 26Diagram 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 27Oliver Lodge's 1894 lectures on Hertz demonstrated how to transmit and detect radio waves. (from History of radio)
... that the Armenian Radio jokes are neither about radio nor are they Armenian?
... 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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