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. In radio navigation systems such as GPS and VOR, a mobile receiver accepts radio signals from 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...)
Different parts of the radio spectrum are allocated by the ITU for different radio transmission technologies and applications; some 40 radiocommunication services are defined in the ITU's Radio Regulations (RR). In some cases, parts of the radio spectrum are sold or licensed to operators of private radio transmission services (for example, cellular telephone operators or broadcast television stations). Ranges of allocated frequencies are often referred to by their provisioned use (for example, cellular spectrum or television spectrum). Because it is a fixed resource which is in demand by an increasing number of users, the radio spectrum has become increasingly congested in recent decades, and the need to utilize it more effectively is driving modern telecommunications innovations such as trunked radio systems, spread spectrum, ultra-wideband, frequency reuse, dynamic spectrum management, frequency pooling, and cognitive radio. (Full article...)
The following are images from various radio-related articles on Wikipedia.
Image 1Advertisement placed on November 5, 1919, Nieuwe Rotterdamsche Courant announcing PCGG's debut broadcast scheduled for the next evening. (from Radio broadcasting)
Image 2In 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 5Diagram 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 6Around 1920, radio broadcasting started to get popular. A group of women gathered around the radio at the time. (from History of radio)
Image 7Animation 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 enormously. (from Radio wave)
Image 11Donald Manson working as an employee of the Marconi Company (England, 1906) (from History of radio)
Image 12Oliver Lodge's 1894 lectures on Hertz demonstrated how to transmit and detect radio waves (from History of radio)
Image 13Heinrich Rudolf Hertz (1856-1894) proved the existence of electromagnetic radiation (from History of radio)
Image 14British Post Office engineers inspect Guglielmo Marconi's wireless telegraphy (radio) equipment in 1897. (from History of radio)
Image 15Reginald Fessenden (around 1906) (from History of radio)
Image 16Animated 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)
... that Travancore Radio's first English-language broadcaster, Indira Joseph Venniyoor, was paid 69 rupees (then equivalent to US$14.50) for her broadcasts in 1949?
... that San Francisco's "KYOU Radio" was the first terrestrial radio station to broadcast a program format consisting of podcasts?
... that listeners to ESPN's sports podcasts are "13 years younger than" ESPN Radio listeners, according to a company executive?
... that during the trial of Francis Gary Powers, Kansas radio station KBTO presented summaries of Radio Moscow broadcasts alongside other international reports?
... that the relative rarity of the radiodontTitanokorys(video featured) in Marble Canyon suggests that the deposits in which it was found may represent the outermost edge of its distribution in life?
When a radio comedian's program is finally finished it slinks down Memory Lane into the limbo of yesteryear's happy hours. All that the comedian has to show for his years of work and aggravation is the echo of forgotten laughter.
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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