Radio is the technology of communicating using radio waves. 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 the waves. They can be received by other antennas connected to a radio receiver; this is the fundamental principle of radio communication. In addition to communication, radio is used for radar, radio navigation, remote control, remote sensing, and other applications.
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...)
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Governor of New York Thomas E. Dewey and former governor of Minnesota Harold Stassen engaged in the first United States presidential debate on May 17, 1948. The two candidates were competing for the Republican Party nomination for the 1948 presidential election and held the debate shortly before the Oregon primary election. It focused on a single issue: whether the United States should outlaw the American Communist Party. Stassen argued that it should, while Dewey argued that it should not. The debate was broadcast over radio on approximately 900 networks, with an estimated 40–80 million listeners.
Dewey was the front-runner for the Republican nomination in 1948, but Stassen gained a surge of support as some states held primary elections. Stassen challenged Dewey to a public debate throughout the process. As the Oregon primary election approached, Stassen was the favorite to win its delegates. Dewey agreed to a debate in Portland on the condition that he could set the terms, such as forgoing a live audience. (Full article...)
The following are images from various radio-related articles on Wikipedia.
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Image 1November 5, 1919 Nieuwe Rotterdamsche Courant advertisement, announcing PCGG's debut broadcast scheduled for the next evening, using narrow-band frequency modulation (FM). (from Radio broadcasting)
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Image 2Broadcasting tower in Trondheim, Norway (from Radio broadcasting)
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Image 3Diagram 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)
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Image 4Comparison of AM and FM modulated radio waves (from Radio)
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Image 5Wildlife officer tracking radio-tagged mountain lion (from Radio)
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Image 6Animation of a half-wave dipole antenna 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)
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Image 7The Regency TR-1, which used Texas Instruments' NPN transistors, was the world's first commercially produced transistor radio in 1954. Size: 3×5×1.25 inch (7.6×12.7×3.2 cm) (from History of radio)
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Image 8Charles Logwood broadcasting at 2XG in New York City in 1916. (from Radio broadcasting)
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Image 9Radio waves symbol (from Radio wave)
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Image 10Volkswagen's RNS-510 receiver supports Sirius Satellite Radio. (from Radio)
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Image 11Rotating marine radar antenna on a ship (from Radio)
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Image 12The first commercial AM Audion vacuum tube radio transmitter, built in 1914 by Lee De Forest who invented the Audion ( triode) in 1906 (from History of radio)
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Image 13Early pioneers of radio science and technology in the United States including Charles Steinmetz, David Sarnoff, Irving Langmuir and Alfred Goldsmith in 1921, photographed next to the antenna feed wires of the New Brunswick Marconi Station, one of the first transatlantic radio links. Photo includes Albert Einstein as a visiting guest. (from History of radio)
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Image 14Reginald Fessenden (around 1906) (from History of radio)
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Image 15Localizer antenna array at Heathrow Airport, London (from Radio)
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Image 17An early iPhone with its GPS navigation app in use. (from Radio)
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Image 18Heinrich Rudolf Hertz (1856–1894) proved the existence of electromagnetic radiation. (from History of radio)
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Image 19Control room and radio studio of the Finnish broadcasting company Yleisradio (YLE) in the 1930s. (from Radio broadcasting)
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Image 20A laptop (with Wi-Fi module) and a typical home wireless router (on the right) connecting it to the Internet. The laptop shows its own photo (from Radio)
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Image 21Radio 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)
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Image 22Around 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)
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Image 23Oliver Lodge's 1894 lectures on Hertz demonstrated how to transmit and detect radio waves. (from History of radio)
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Image 24Animated 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)
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Image 25In 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)
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Image 26Early experiment demonstrating refraction of microwaves by a paraffin lens by John Ambrose Fleming in 1897 (from History of radio)
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Image 27Frequency spectrum of a typical modulated AM or FM radio signal. It consists of a component C at the carrier wave frequency  with the modulated information contained in two narrow bands of frequencies called sidebands ( SB) just above and below the carrier frequency. The bandwidth ( BW) is the amount of spectrum occupied by the sidebands. (from Radio)
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Image 28Use of a sound broadcasting station (from Radio broadcasting)
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Image 29Worldwide presence of Radio Maria broadcasters (from Radio broadcasting)
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Image 30Neighborhood wireless WAN router on telephone pole (from Radio)
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Image 31British Post Office engineers inspect Guglielmo Marconi's wireless telegraphy (radio) equipment in 1897. (from History of radio)
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Image 32Donald Manson working as an employee of the Marconi Company (England, 1906) (from History of radio)
List articles
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Radio is the most intimate and socially personal medium in the world.
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ELF 3 Hz/100 Mm 30 Hz/10 Mm
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SLF 30 Hz/10 Mm 300 Hz/1 Mm
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ULF 300 Hz/1 Mm 3 kHz/100 km
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VLF 3 kHz/100 km 30 kHz/10 km
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LF 30 kHz/10 km 300 kHz/1 km
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MF 300 kHz/1 km 3 MHz/100 m
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HF 3 MHz/100 m 30 MHz/10 m
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VHF 30 MHz/10 m 300 MHz/1 m
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UHF 300 MHz/1 m 3 GHz/100 mm
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SHF 3 GHz/100 mm 30 GHz/10 mm
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EHF 30 GHz/10 mm 300 GHz/1 mm
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THF 300 GHz/1 mm 3 THz/0.1 mm
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Community radio, Music radio, Old-time radio, Radio comedy, Radio documentary, Radio drama, Sports radio, Talk Radio, Top 40
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BBC Radio, Blue Network, Columbia Broadcasting System, Mutual Broadcasting System, National Broadcasting Company, Sirius Satellite Radio, XM Satellite Radio
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Fred Allen, Gracie Allen, Don Ameche, Jack Benny, Edgar Bergen, Jagadish Chandra Bose, George Burns, Charlamagne tha God, Ronald Colman, Jim Connors, Frank Conrad, Norman Corwin, Charles Coughlin, Frankie Crocker, Ebro Darden, Alice Faye, Stan Freberg, Sean Hannity, Vaughn Harper, Phil Harris, Bob Hope, Hal Jackson, Spike Jones, Tom Joyner, Hans von Kaltenborn, Larry Elder, Larry King, Kay Kyser, Frances Langford, Rush Limbaugh, Guglielmo Marconi, Angie Martinez, Elizabeth McLeod, J. Carrol Naish, Ozzie Nelson, Arch Oboler, Dorothy Parker, Virginia Payne, Harold Peary, David Sarnoff, Red Skelton, Kate Smith, Stephen A. Smith, Howard Stern, Nikola Tesla, Jonathan Toubin, Lurene Tuttle, Rudy Vallée, Fred Waring, Orson Welles, Wendy Williams, Angela Yee
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Abbott and Costello, Amos 'n' Andy, Arch Oboler's Plays, The Breakfast Club, Burns and Allen, Cavalcade of America, CBS Radio Mystery Theater, Dragnet, Duffy's Tavern, Ebro in the Morning, Fibber McGee and Molly, The Goldbergs, The Howard Stern Show, Inner Sanctum Mysteries, The Jack Benny Program, Life with Luigi, Lights Out, Lux Radio Theater, Opie and Anthony, The Archers, The Hitchhiker's Guide to the Galaxy, The Phil Harris-Alice Faye Show, Quiz Kids, The Screen Guild Theater, The Shadow, Suspense, Theater Guild on the Air, Twenty Questions, The Whistler, Yours Truly, Johnny Dollar, Tom Joyner Morning Show, Rush Limbaugh Show
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| Technology
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Amateur radio, AM broadcasting, FM broadcasting, International broadcasting, Internet Radio, Digital Radio Mondiale, HD Radio, Digital Audio Broadcasting, GNU Radio, Software-defined radio, Transistor radio, Vacuum tube, Pirate radio
Top 40
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Radio promotion
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- Radio December 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 Stations February 15, 2005 "...to coordinate the activities of creating and maintaining articles about radio stations." (Example: Pulse FM Kingborough & Huon)
- Podcasting January 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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