The following outline is provided as an overview of and topical guide to radio:

Radio 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 connec ...

– transmission of signals by modulation of

electromagnetic waves In physics, electromagnetic radiation (EMR) is a self-propagating wave of the electromagnetic field that carries momentum and radiant energy through space. It encompasses a broad spectrum, classified by frequency or its inverse, wavelength, ran ...

with

frequencies Frequency is the number of occurrences of a repeating event per unit of time. Frequency is an important parameter used in science and engineering to specify the rate of oscillatory and vibratory phenomena, such as mechanical vibrations, audio ...

below those of

visible light Light, visible light, or visible radiation is electromagnetic radiation that can be perceived by the human eye. Visible light spans the visible spectrum and is usually defined as having wavelengths in the range of 400–700 nanometres (nm ...

.Dictionary of Electronics By Rudolf F. Graf (1974). Page 467. Electromagnetic radiation travels by means of oscillating

electromagnetic field An electromagnetic field (also EM field) is a physical field, varying in space and time, that represents the electric and magnetic influences generated by and acting upon electric charges. The field at any point in space and time can be regarde ...

s that pass through the air and the

vacuum A vacuum (: vacuums or vacua) is space devoid of matter. The word is derived from the Latin adjective (neuter ) meaning "vacant" or "void". An approximation to such vacuum is a region with a gaseous pressure much less than atmospheric pressur ...

of space. Information is carried by systematically changing ( modulating) some property of the radiated waves, such as

amplitude The amplitude of a periodic variable is a measure of its change in a single period (such as time or spatial period). The amplitude of a non-periodic signal is its magnitude compared with a reference value. There are various definitions of am ...

frequency Frequency is the number of occurrences of a repeating event per unit of time. Frequency is an important parameter used in science and engineering to specify the rate of oscillatory and vibratory phenomena, such as mechanical vibrations, audio ...

, phase, or pulse width. When radio waves pass an electrical conductor, the oscillating fields induce an alternating current in the conductor. This can be detected and transformed into sound or other signals that carry information.

Essence of radio

Broadcasting Broadcasting is the data distribution, distribution of sound, audio audiovisual content to dispersed audiences via a electronic medium (communication), mass communications medium, typically one using the electromagnetic spectrum (radio waves), ...

Wireless Wireless communication (or just wireless, when the context allows) is the transfer of information (''telecommunication'') between two or more points without the use of an electrical conductor, optical fiber or other continuous guided transm ...

Radio broadcasting Radio broadcasting is the broadcasting of audio signal, audio (sound), sometimes with related metadata, by radio waves to radio receivers belonging to a public audience. In terrestrial radio broadcasting the radio waves are broadcast by a lan ...

Applications

Amateur radio Amateur radio, also known as ham radio, is the use of the radio frequency radio spectrum, spectrum for purposes of non-commercial exchange of messages, wireless experimentation, self-training, private recreation, radiosport, contesting, and emer ...

Direction finding Direction finding (DF), radio direction finding (RDF), or radiogoniometry is the use of radio waves to determine the direction to a radio source. The source may be a cooperating radio transmitter or may be an inadvertent source, a naturall ...

AM broadcasting AM broadcasting is radio broadcasting using amplitude modulation (AM) transmissions. It was the first method developed for making audio radio transmissions, and is still used worldwide, primarily for medium wave (also known as "AM band") transm ...

FM broadcasting FM broadcasting is a method of radio broadcasting that uses frequency modulation (FM) of the radio broadcast carrier wave. Invented in 1933 by American engineer Edwin Armstrong, wide-band FM is used worldwide to transmit high fidelity, high-f ...

Shortwave broadcasting Shortwave radio is radio transmission using radio frequencies in the shortwave bands (SW). There is no official definition of the band range, but it always includes all of the high frequency band (HF), which extends from 3 to 30 MHz (app ...

Radar Radar is a system that uses radio waves to determine the distance ('' ranging''), direction ( azimuth and elevation angles), and radial velocity of objects relative to the site. It is a radiodetermination method used to detect and track ...

Radio astronomy Radio astronomy is a subfield of astronomy that studies Astronomical object, celestial objects using radio waves. It started in 1933, when Karl Jansky at Bell Telephone Laboratories reported radiation coming from the Milky Way. Subsequent observat ...

Radio navigation Radio navigation or radionavigation is the application of radio waves to geolocalization, determine a position of an object on the Earth, either the vessel or an obstruction. Like radiolocation, it is a type of Radiodetermination-satellite servi ...

Radiotelephone A radiotelephone (or radiophone), abbreviated RT, is a radio communication system for conducting a conversation; radiotelephony means telephony by radio. It is in contrast to ''radiotelegraphy'', which is radio transmission of telegrams (messag ...

Satellite radio Satellite radio is defined by the International Telecommunication Union (ITU)'s ITU Radio Regulations (RR) as a '' broadcasting-satellite service''. The satellite's signals are broadcast nationwide, across a much wider geographical area than te ...

Software-defined radio Software-defined radio (SDR) is a radio communication system where components that conventionally have been implemented in analog hardware (e.g. mixers, filters, amplifiers, modulators/ demodulators, detectors, etc.) are instead implemented ...

Two-way radio A two-way radio is a radio transceiver (a radio that can both transmit and receive radio waves), which is used for bidirectional person-to-person voice communication with other users with similar radios, in contrast to a broadcast receiver, whi ...

(Aviation, Land-based commercial, Government, Marine) ** Mission critical communication TETRA and P25 *

Wireless power transfer Wireless power transfer (WPT; also wireless energy transmission or WET) is the transmission of electrical energy without wires as a physical link. In a wireless power transmission system, an electric power source, electrically powered transmitte ...

Types of radio broadcasting

Campus radio Campus radio (also known as college radio, university radio or student radio) is a type of radio station that is run by the students of a college, university or other educational institution. Programming may be exclusively created or produced ...

Commercial radio Commercial broadcasting (also called private broadcasting) is the broadcasting of television programs and radio programming by privately owned corporate media, as opposed to state sponsorship, for example. It was the United States' first model ...

Community radio Community radio is a radio service offering a third model of radio broadcasting in addition to commercial broadcasting, commercial and public broadcasting. Community broadcasting, Community stations serve geographic communities and communities o ...

International broadcasting International broadcasting consists of radio and television transmissions that purposefully cross international boundaries, often with then intent of allowing expatriates to remain in touch with their countries of origin as well as educate, inform ...

Internet radio Internet radio, also known as online radio, web radio, net radio, streaming radio, e-radio and IP radio, is a digital audio service transmitted via the Internet. Broadcasting on the Internet is usually referred to as webcasting since it is not ...

Music radio Music radio is a radio format in which music is the main broadcast content. After television replaced old time radio's dramatic content, music formats became dominant in many countries. Radio drama and comedy continue, often on public radio. M ...

Pirate radio Pirate radio is a radio station that broadcasts without a valid license, whether an invalid license or no license at all. In some cases, radio stations are considered legal where the signal is transmitted, but illegal where the signals are rec ...

Public radio Public broadcasting (or public service broadcasting) is radio, television, and other electronic media outlets whose primary mission is public service with a commitment to avoiding political and commercial influence. Public broadcasters receive ...

Radio broadcasting topics

Disc jockey A disc jockey, more commonly abbreviated as DJ, is a person who plays recorded music for an audience. Types of DJs include Radio personality, radio DJs (who host programs on music radio stations), club DJs (who work at nightclubs or music fes ...

Radio documentary A radio documentary is a spoken word radio format devoted to non-fiction narrative. It is broadcast on radio as well as distributed through media such as tape, CD, and podcast A podcast is a Radio program, program made available in digital ...

Radio format A radio format or programming format (not to be confused with broadcast programming) describes the overall content broadcast on a radio station. The radio format emerged mainly in the United States in the 1950s, at a time when Radio broadcasting, ...

Radio personality A radio personality is a person who has an on-air position in radio broadcasting. A radio personality who hosts a radio show is also known as a radio host (North American English), radio presenter (British English) or radio jockey. Radio personali ...

Radio programming Radio programming is the process of organising a schedule of radio content for commercial broadcasting and public broadcasting by radio stations. History The original inventors of radio, from Guglielmo Marconi's time on, expected it to be use ...

History of radio

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 bega ...

* Invention of radio *

Wireless telegraphy Wireless telegraphy or radiotelegraphy is the transmission of text messages by radio waves, analogous to electrical telegraphy using electrical cable, cables. Before about 1910, the term ''wireless telegraphy'' was also used for other experimenta ...

Spark-gap transmitter A spark-gap transmitter is an obsolete type of transmitter, radio transmitter which generates radio waves by means of an electric spark."Radio Transmitters, Early" in Spark-gap transmitters were the first type of radio transmitter, and were the m ...

Alexanderson alternator An Alexanderson alternator is a rotating machine, developed by Ernst Alexanderson beginning in 1904, for the generation of high-frequency alternating current for use as a radio transmitter. It was one of the first devices capable of generating th ...

Antique radio An antique radio is a radio receiving set that is collectible because of its age and rarity. Types of antique radio Morse receivers The first radio receivers used a coherer and sounding board, and were only able to receive continuous wave (CW) ...

Coherer The coherer was a primitive form of radio signal detector used in the first radio receivers during the wireless telegraphy era at the beginning of the 20th century. Its use in radio was based on the 1890 findings of French physicist Édouard Bra ...

Continuous wave A continuous wave or continuous waveform (CW) is an electromagnetic wave of constant amplitude and frequency, typically a sine wave, that for mathematical analysis is considered to be of infinite duration. It may refer to e.g. a laser or particl ...

* Crystal radio *

Vacuum tube A vacuum tube, electron tube, thermionic valve (British usage), or tube (North America) is a device that controls electric current flow in a high vacuum between electrodes to which an electric voltage, potential difference has been applied. It ...

Amplitude modulation Amplitude modulation (AM) is a signal modulation technique used in electronic communication, most commonly for transmitting messages with a radio wave. In amplitude modulation, the instantaneous amplitude of the wave is varied in proportion t ...

Old-time radio The Golden Age of Radio, also known as the old-time radio (OTR) era, was an era of radio in the United States where it was the dominant electronic home entertainment medium. It began with the birth of commercial radio broadcasting in the earl ...

Radioteletype Radioteletype (RTTY) is a telecommunications system consisting originally of two or more electromechanical teleprinters in different locations connected by radio rather than a wired link. Radioteletype evolved from earlier landline teleprinter ...

* Table of years in radio (events by year) * Timeline of radio

Radio science

Radio science One way of outlining the subject of ''radio science'' is listing the topics associated with it by authoritative bodies. Union of Radio Science International (URSI) The International Union of Radio Science has several commissions corresponding t ...

Antenna (radio) In radio-frequency engineering, an antenna (American English) or aerial (British English) is an electronic device that converts an alternating current, alternating electric current into radio waves (transmitting), or radio waves into an elect ...

Carrier current Carrier current transmission, originally called wired wireless, employs guided low-power Radio frequency, radio-frequency signals, which are transmitted along electrical conductors. The transmissions are picked up by receivers that are either conne ...

Electromagnetic radiation In physics, electromagnetic radiation (EMR) is a self-propagating wave of the electromagnetic field that carries momentum and radiant energy through space. It encompasses a broad spectrum, classified by frequency or its inverse, wavelength ...

Radio frequency Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around to around . This is roughly between the u ...

(electricity and electromagnetic waves) *

Radio spectrum The radio spectrum is the part of the electromagnetic spectrum with frequencies from 3 Hz to 3,000 GHz (3 THz). Electromagnetic waves in this frequency range, called radio waves, are widely used in modern technology, particula ...

(electromagnetic waves) *

Radio propagation Radio propagation is the behavior of radio waves as they travel, or are wave propagation, propagated, from one point to another in vacuum, or into various parts of the atmosphere. As a form of electromagnetic radiation, like light waves, radio w ...

Receiver (radio) In radio, radio communications, a radio receiver, also known as a receiver, a wireless, or simply a radio, is an electronic device that receives radio waves and converts the information carried by them to a usable form. It is used with an ante ...

Transmitter In electronics and telecommunications, a radio transmitter or just transmitter (often abbreviated as XMTR or TX in technical documents) is an electronic device which produces radio waves with an antenna (radio), antenna with the purpose of sig ...

Types of radio emissions The International Telecommunication Union uses an internationally agreed system for classifying radio frequency signals. Each type of radio emission is classified according to its Bandwidth (signal processing), bandwidth, method of modulation, n ...

Radio technology

* Antenna matching unit *

Batteryless radio A batteryless radio is a type of radio receiver that does not require the use of a battery (electricity), battery to provide it with electrical power. Originally this referred to units which could be used directly by AC mains supply (mains radio ...

Digital radio Digital radio is the use of digital technology to transmit or receive across the radio spectrum. Digital transmission by radio waves includes digital broadcasting, and especially digital audio radio services. This should not be confused with In ...

* DTV radio *

Preselector A preselector is a name for an electronic device that connects between a radio antenna and a radio receiver. The preselector is a band-pass filter that blocks troublesome out-of-tune frequencies from passing through from the antenna into ...

* Radio frequency power amplifier * Radio software * Shortwave radio receiver *

Superheterodyne receiver A superheterodyne receiver, often shortened to superhet, is a type of radio receiver that uses frequency mixing to convert a received signal to a fixed intermediate frequency (IF) which can be more conveniently processed than the original car ...

Tuner (radio) In electronics and radio, a tuner is a type of receiver subsystem that receives RF transmissions, such as AM or FM broadcasts, and converts the selected carrier frequency into a form suitable for further processing or output, such as to a ...

* TV radio

Radio stations

* Radio stations in Africa * Radio stations in Asia * Radio stations in Europe * Radio stations in North America * Radio stations in Oceania * Radio stations in South America

Persons influential in the field of radio

Michael Faraday Michael Faraday (; 22 September 1791 – 25 August 1867) was an English chemist and physicist who contributed to the study of electrochemistry and electromagnetism. His main discoveries include the principles underlying electromagnetic inducti ...

(predictions) *

James Clerk Maxwell James Clerk Maxwell (13 June 1831 – 5 November 1879) was a Scottish physicist and mathematician who was responsible for the classical theory of electromagnetic radiation, which was the first theory to describe electricity, magnetism an ...

(theoretical work) *

Heinrich Rudolf Hertz Heinrich Rudolf Hertz (; ; 22 February 1857 – 1 January 1894) was a German physicist who first conclusively proved the existence of the electromagnetic waves predicted by James Clerk Maxwell's equations of electromagnetism. Biography Heinric ...

(experimental demonstrations) *

Oliver Lodge Sir Oliver Joseph Lodge (12 June 1851 – 22 August 1940) was an English physicist whose investigations into electromagnetic radiation contributed to the development of Radio, radio communication. He identified electromagnetic radiation indepe ...

(techniques for transmitting and receiving radio waves) *

Guglielmo Marconi Guglielmo Giovanni Maria Marconi, 1st Marquess of Marconi ( ; ; 25 April 1874 – 20 July 1937) was an Italian electrical engineer, inventor, and politician known for his creation of a practical radio wave-based Wireless telegraphy, wireless tel ...

(adapted radio waves for use in signalling) *

Reginald Fessenden Reginald Aubrey Fessenden (October 6, 1866 – July 22, 1932) was a Canadian-American electrical engineer and inventor who received hundreds of List of Reginald Fessenden patents, patents in fields related to radio and sonar between 1891 and 1936 ...

(developed

amplitude modulation Amplitude modulation (AM) is a signal modulation technique used in electronic communication, most commonly for transmitting messages with a radio wave. In amplitude modulation, the instantaneous amplitude of the wave is varied in proportion t ...

(AM) radio and first voice transmission) *

Edwin Howard Armstrong Edwin Howard Armstrong (December 18, 1890 – February 1, 1954) was an American electrical engineer and inventor who developed FM (frequency modulation) radio and the superheterodyne receiver system. He held 42 patents and received numerous awa ...

(developed

frequency modulation Frequency modulation (FM) is a signal modulation technique used in electronic communication, originally for transmitting messages with a radio wave. In frequency modulation a carrier wave is varied in its instantaneous frequency in proporti ...

(FM) )

Alternatives

Cable FM Cable radio is radio broadcasting into homes and businesses via a cable. This can be a coaxial cable used for television, or a telephone line. It is generally used for the same reason as cable TV was in its early days when it was "community ante ...

Free-space optical communication Free-space optical communication (FSO) is an optical communication technology that uses light propagating in free space to wirelessly transmit data for telecommunications or computer networking over long distances. "Free space" means air, oute ...

(FSO) *

Other

* Bandstacked * * Years in radio

References

External links

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