Shortwave relay station

Shortwave relay stations are transmitter sites used by international broadcasters to extend their coverage to areas that cannot be reached easily from their home state. E.g., the BBC operates an extensive net of relay stations.[1]

These days the programs are fed to the relay sites by satellite, cable/optical fiber or the Internet. Frequencies, transmitter power and antennas depend on the desired coverage. Some regional relays even operate in the medium wave or FM bands.[2]

Relay stations are also important to reach listeners in countries that practice radio jamming. Depending on the effect of the shortwave dead zone the target countries can jam the programs only locally, e.g. for bigger cities. For this purpose Radio Free Europe/Radio Liberty with studios in Munich, Germany operated a relay station in Portugal, in the extreme west of Europe, to reach then-communist Eastern Europe.[3]

ALLISS antenna as viewed underneath

Variations in design

Two and only one broadcasting technology couples all of the components of a traditional shortwave relay station into one unit: the ALLISS module. For persons totally unfamiliar with the concepts of how shortwave relay stations operate this design may be the most understandable.

The ALLISS module is a fully rotatable antenna system for high power (typically 500 kW only) shortwave radio broadcasting—it essentially is a self contained shortwave relay station.

Most of the world's shortwave relay stations do not use this technology, due to its cost (15m EUR per ALLISS module: Transmitter + Antenna + Automation equipment).

Planning and design

A traditional shortwave relay station—depending on how many transmitters and antennas that it will have—may take up to two years to plan. After planning is completed, it may take up to five years to construct the relay station.

The historically long design and planning cycle for shortwave relay stations ended in the 1990s. Many advanced software planning tools (not related to the relay station design proper) became available. Choosing a series of sites for a relay station is about 100 times faster using Google Earth, for example. With the modern graphical version of Ioncap, simplified propagation studies can completed in less than a week for any chosen site.

In some cases, existing relay stations can have their designs more or less duplicated, thus speeding up development time. However, there is one general exception to this: the ALLISS Module. From initial planning to deployment of ALLISS Modules may take a mere 1.5 years to 9 months depending on the number of modules deployed at one time in a particular sector of a country.

How relay stations operate

These are considered general operating parameters:

  • 20 hours per day, but geopolitical reasons may dictate some stations run 24 hours per day (a 168-hour week)
  • Generally 360 days per year, depending on the number of redundant transmitters and antennas
  • Relay Stations generally consume from 250 kilowatts (kW) to 10 megawatts (MW)
  • A single 100 kW SW transmitter consumes 225 kW RMS as a general rule
  • A single 300 kW SW transmitter consumes 625 kW RMS as a general rule
  • Modulator efficiency: Class-B modulators have about a 65% efficiency level, but digital (PDM or PSM or hybrid variants) modulators have about an 85% efficiency level as a general rule (for Amplitude Modulation)
  • Broadcast times and frequencies are under ITU regulation

How relay stations are designed

General requirements of shortwave relay stations:

  • Road access (fairly universal)
  • HVAC mains access building or transformer in the transmitter building itself
  • Staff quarters (if the relay station is not fully automated)
  • Incoming audio processing centre, but since the mid-1980s this has evolved into one to five rack units
  • Transmitter hall (50 kW, 100 kW, 250 kW, 300 kW, 500 kW shortwave transmitter)
  • Switch matrix (but these are not typically used by ALLISS modules)
  • Baluns (but their use is not always required nor universal)
  • antenna tuners (sometimes called ATUs or roller coasters because of their appearance)
  • Feeder lines (coax cable and open feeder lines are the most common feeders in use)
  • HRS-type antennas, or occasionally log-periodic (horizontal)
  • In parts of the developing world log-periodic (horizontal) antennas are used to provide less directional gain to a target area.

Where the broadcast programs go

  • generally to target areas that are more than 300 km from the transmitter site
  • most shortwave relay station target areas are 1500 km to 3500 km from the transmitter site

Mobile relay stations

The IEEE Book series "The History of International Broadcasting" (Volume I) describes mobile shortwave relay stations used by the German propaganda ministry during WWII, to avoid them being located by radio direction finding and bombed by the Allies. They consisted of a generator truck, transmitter truck and an antenna truck, and are thought to have had a radiated power of about 50 kW. Radio Industry Zagreb (RIZ Transmitters) currently produces mobile shortwave transmitters.

Notable sites : Issoudun

05issoudun alliss Volga

Volga ALLISS Module

06issoudun alliss Gange

Ganges ALLISS Module

02issoudun feeders+rideaux

Former RFI Issoudun Relay station feeders and curtain arrays

01issoudun rideaux E

Former RFI Issoudun Relay curtain arrays

The International broadcasting center of TDF (Télédiffusion de France) is at Issoudun/Saint-Aoustrille. As of 2011, Issoudun is utilized by TDF for shortwave transmissions. The site uses 12 rotary ALLISS antennas fed by 12 transmitters of 500 kW each to transmit shortwave broadcasts by Radio France Internationale (RFI), along with other broadcast services.

See also


  1. ^ BBC Cyprus relay. Retrieved 2011-04-01.
  2. ^ How to listen to the BBC. Retrieved 2011-04-01.
  3. ^ Radio Free Europe. Retrieved 2011-04-01.

1worldspace, known for most of its existence simply as 'WorldSpace', is a defunct satellite radio network that in its heyday provided service to over 170,000 subscribers in eastern and southern Africa, the Middle East, and much of Asia with 96% coming from India. It was profitable in India, with 450,000 subscribers.Timbre Media along with Saregama India planned to relaunch the company.The satellites AfriStar and AsiaStar however are now being used by the Yazmi USA, LLC run by WorldSpace's former CEO Noah A. Samara. The company claims to have built the first satellite-to-tablet content delivery system. The system primarily aims at providing educational services to rural areas in developing countries. The first pilots of the technology are said to be taking place in India (with 30,000 licenses) and the sub-Saharan region in Africa, with the latest trials in two schools in South Africa, in Rietkol, in Mpumalanga Province, and at Heathfield, in Western Cape.


ALLISS is a fully rotatable antenna system for high power shortwave radio broadcasting in the 6 MHz to 26 MHz range. An ALLISS module is a self-contained shortwave relay station that is used for international broadcasting.

Ascension Island

Ascension Island is an isolated volcanic island, 7°56' south of the Equator in the South Atlantic Ocean. It is about 1,600 kilometres (1,000 mi) from the coast of Africa and 2,250 kilometres (1,400 mi) from the coast of Brazil. It is governed as part of the British Overseas Territory of Saint Helena, Ascension and Tristan da Cunha, of which the main island, Saint Helena, is around 1,300 kilometres (800 mi) to the southeast. The territory also includes the sparsely-populated Tristan da Cunha archipelago, some 3,730 kilometres (2,300 mi) to the south, about halfway to the Antarctic Circle.

The island is named after the day of its recorded discovery, Ascension Day. It was an important safe haven and coaling station to mariners and for commercial airliners during the days of international air travel by flying boats. During World War II it was an important naval and air station, especially providing antisubmarine warfare bases in the Battle of the Atlantic. Ascension Island was garrisoned by the British Admiralty from 22 October 1815 to 1922.

The island is the location of RAF Ascension Island, which is a Royal Air Force station, a European Space Agency rocket tracking station, an Anglo-American signals intelligence facility and the BBC World Service Atlantic Relay Station. The island was used extensively as a staging point by the British military during the Falklands War. Ascension Island hosts one of four ground antennas (others are on Kwajalein Island, Diego Garcia, and Cape Canaveral) that assist in the operation of the Global Positioning System (GPS) navigational system. NASA operates a Meter Class Autonomous Telescope (MCAT) on Ascension Island for tracking orbital debris, which is potentially hazardous to operating spacecraft and astronauts, at a facility called the John Africano NASA/AFRL Orbital Debris Observatory.


Bonaire (pronounced or ; Dutch: Bonaire, pronounced [boːˈnɛːr(ə)]; Papiamento: Boneiru, pronounced [buˈneiru]) is an island in the Leeward Antilles in the Caribbean Sea. Its capital is Kralendijk, located near the ocean on the lee side of the island. Aruba, Bonaire and Curaçao form the ABC islands located 80 km (50 miles) off the coast of Venezuela. Unlike much of the Caribbean region, the ABC islands lie outside Hurricane Alley. The islands have an arid climate that attracts visitors seeking warm, sunny weather year round. Bonaire is a popular snorkeling and scuba diving destination because of its multiple shore diving sites and easy access to the island's fringing reefs.

As of 1 January 2016, the island's population totaled approximately 19,408 permanent residents, an increase of 500 from 2015. The island's total land area is 288 square kilometres (111 sq mi); it is 38.6 kilometres (24.0 mi) long from north to south, and ranges from 4.8–8 kilometres (3.0–5.0 mi) wide from east to west. A short 0.80 kilometres (0.50 mi) west of Bonaire across the sea is the uninhabited islet Klein Bonaire with a total land area of 6 km2 (2.3 sq mi). Klein has low growing vegetation, no trees, and is bordered by white sandy beaches and a fringing reef. The reefs, beaches and on-island reserves located on both Bonaire and Klein Bonaire are under the protection of the Bonaire National Marine Park, and managed by Stichting Nationale Parken Bonaire (STINAPA).Bonaire was part of the Netherlands Antilles until the country's dissolution in 2010, when the island became a special municipality (officially “public body”) within the country of the Netherlands. It is one of the three BES islands in the Caribbean, along with Sint Eustatius and Saba. An 80% majority of Bonaire's population are Dutch nationals, and nearly 60% of its residents were born in the former Netherlands Antilles and Aruba.

Broadcast relay station

A broadcast relay station, also known as a satellite station, relay transmitter, broadcast translator (U.S.), re-broadcaster (Canada), repeater (two-way radio) or complementary station (Mexico), is a broadcast transmitter which repeats (or transponds) the signal of a radio or television station to an area not covered by the originating station. It expands the broadcast range of a television or radio station beyond the primary signal's original coverage or improves service in the original coverage area. The stations may be (but are not usually) used to create a single-frequency network. They may also be used by an FM or AM radio station to establish a presence on the other band.

A re-broadcaster may be owned by a community group, rather than the owner of the primary station. WHLS/WHLX in Port Huron, Michigan purchased a translator and switched to an alternative rock format shortly afterwards without mentioning the original FM translator, except for its legally required top-of-the-hour ID. No AM frequencies have been mentioned.


Broadcasting is the distribution of audio or video content to a dispersed audience via any electronic mass communications medium, but typically one using the electromagnetic spectrum (radio waves), in a one-to-many model. Broadcasting began with AM radio, which came into popular use around 1920 with the spread of vacuum tube radio transmitters and receivers. Before this, all forms of electronic communication (early radio, telephone, and telegraph) were one-to-one, with the message intended for a single recipient. The term broadcasting evolved from its use as the agricultural method of sowing seeds in a field by casting them broadly about. It was later adopted for describing the widespread distribution of information by printed materials or by telegraph. Examples applying it to "one-to-many" radio transmissions of an individual station to multiple listeners appeared as early as 1898.Over the air broadcasting is usually associated with radio and television, though in recent years, both radio and television transmissions have begun to be distributed by cable (cable television). The receiving parties may include the general public or a relatively small subset; the point is that anyone with the appropriate receiving technology and equipment (e.g., a radio or television set) can receive the signal. The field of broadcasting includes both government-managed services such as public radio, community radio and public television, and private commercial radio and commercial television. The U.S. Code of Federal Regulations, title 47, part 97 defines "broadcasting" as "transmissions intended for reception by the general public, either direct or relayed". Private or two-way telecommunications transmissions do not qualify under this definition. For example, amateur ("ham") and citizens band (CB) radio operators are not allowed to broadcast. As defined, "transmitting" and "broadcasting" are not the same.

Transmission of radio and television programs from a radio or television station to home receivers by radio waves is referred to as "over the air" (OTA) or terrestrial broadcasting and in most countries requires a broadcasting license. Transmissions using a wire or cable, like cable television (which also retransmits OTA stations with their consent), are also considered broadcasts but do not necessarily require a license (though in some countries, a license is required). In the 2000s, transmissions of television and radio programs via streaming digital technology have increasingly been referred to as broadcasting as well.


CKCX was the callsign used for the Canadian Broadcasting Corporation's shortwave transmitter complex near Sackville, New Brunswick at the Tantramar Marshes. The Sackville Relay Station was operated by Radio Canada International and broadcast its programming around the world as well as relay transmissions from several foreign shortwave broadcasters. Domestically, it transmitted broadcasts on 9.625 MHz to northern Quebec by CBC North, the James Bay Cree Communications Society and Taqramiut Nipingat, the Inuit communications society of the Nunavik region of northern Quebec. The CKCX designation was assigned after CBC Radio's CBA, under whose licence the Sackville complex originally operated, moved to Moncton in 1968. Sackville was also used by Radio Japan, China Radio International, Voice of Vietnam, BBC World Service, Deutsche Welle and Radio Korea as part of a transmitter time exchange agreement.

Carnarvon, Western Australia

Carnarvon is a coastal town situated approximately 900 kilometres (560 mi) north of Perth, Western Australia. It lies at the mouth of the Gascoyne River on the Indian Ocean. The popular Shark Bay world heritage area lies to the south of the town and the Ningaloo Reef and the popular tourist town of Exmouth lie to the north. Within Carnarvon is the Mungullah Aboriginal Community. Inland, Carnarvon has strong links with the town of Gascoyne Junction and the Burringurrah Community. At the 2016 census, Carnarvon had a population of 4,426.

Curtain array

Curtain arrays are a class of large multielement directional wire radio transmitting antennas, used in the shortwave radio bands. They are a type of reflective array antenna, consisting of multiple wire dipole antennas, suspended in a vertical plane, often in front of a "curtain" reflector made of a flat vertical screen of many long parallel wires. These are suspended by support wires strung between pairs of tall steel towers, up to 300 ft (90 m) high. They are used for long-distance skywave (or skip) transmission; they transmit a beam of radio waves at a shallow angle into the sky just above the horizon, which is reflected by the ionosphere back to Earth beyond the horizon. Curtain antennas are mostly used by international short wave radio stations to broadcast to large areas at transcontinental distances.Because of their powerful directional characteristics, curtain arrays are often used in government propaganda radio stations to beam propaganda broadcasts over national borders into other nations. For example, curtain arrays were used by Radio Free Europe and Radio Liberty to broadcast into Eastern Europe.

Index of radio propagation articles

This is an index to articles about terms used in discussion of radio propagation.

National Radio and Television Administration

The National Radio and Television Administration (NRTA), formerly the State Administration of Radio, Film, and Television (SARFT, 1998–2013) and the State Administration of Press, Publication, Radio, Film and Television (SAPPRFT, 2013–2018), is a ministry-level executive agency directly under the State Council of the People's Republic of China. Its main task is the administration and supervision of state-owned enterprises engaged in the television and radio industries.

It directly controls state-owned enterprises at the national level such as China Central Television, China National Radio, China Radio International, as well as other movie and television studios and others non-business organizations.

It is also responsible for censoring any materials that offend the sensibilities of the Chinese government or Chinese cultural standards. An example of such activity is the summer 2007 controversy over the television talent show First Heartthrob.


Novosibirsk (Russian: Новосиби́рск, IPA: [nəvəsʲɪˈbʲirsk]) is the third-most populous city in Russia, after Moscow and St. Petersburg. It is the most populous city in Asian Russia, with a population of 1,612,833 as of the 2018 Census, and is the administrative center of Novosibirsk Oblast as well as of the Siberian Federal District.

The city is located in the southwestern part of Siberia on the banks of the Ob River adjacent to the Ob River Valley, near the large water reservoir formed by the dam of the Novosibirsk Hydro Power Plant. It is split into ten districts and occupies an area of 502.1 square kilometres (193.9 sq mi). It is about 2,800 kilometres (1,700 mi) east from Moscow, 600 kilometres (370 mi) east from Omsk, 1,400 kilometres (870 mi) east from Yekaterinburg, and 645 kilometres (401 mi) west of Krasnoyarsk.

Radio Canada International

Radio Canada International (RCI) is the international broadcasting service of the Canadian Broadcasting Corporation (CBC). Prior to 1970, RCI was known as the CBC International Service. The broadcasting service was also previously referred to as the "Voice of Canada". In June 2012, shortwave services were terminated and RCI became accessible exclusively via the Internet. It also reduced to services in five languages (in contrast with the 14 languages it used in 1990). CBC also ended production of RCI news.

Radio Nepal

Radio Nepal (Nepali: रेडियो नेपाल) is the state-owned Radio broadcasting organisation of Nepal, which was established on 2 April 1951. Initially, the transmission lasted for 4 hours and 30 minutes through a 250-watt short-wave transmitter. Over the years, Radio Nepal has strengthened its institutional capacity considerably and diversified itself in terms of programme format, technical efficiency and coverage. Radio Nepal airs programmes on short wave medium wave (AM) and FM frequencies.

Regular broadcasts last for sixteen hours every day, which includes two hours of regional broadcasts between 9:30 and 11:00 in the morning and 18:05 and 18:30 in the evening. However, on public holidays, there is an additional two hours, extending the total duration to eighteen hours. FM Kathmandu, the first FM channel covering Kathmandu valley and adjoining areas, was started in 1995 from its premises at Singha Durbar, Kathmandu.

On 19th May 2016, An environmental song, Melancholy was recorded by 365 renowned Nepali singers and musicians in a single day at Radio Nepal studio. This song was attempt Guinness World Records is conceptualized, written, music composed and directed by Environmentalist Nipesh DHAKA.

Radio Netherlands Worldwide

Radio Netherlands Worldwide (RNW; Dutch: Radio Nederland Wereldomroep) was a public radio and television network based in Hilversum, producing and transmitting programmes for international audiences outside the Netherlands. Radio Netherlands Worldwide also distributed content via web and e-mail technology from as early as 1992.

Its services in Dutch ended on 10 May 2012. English and Indonesian languages ceased on 29 June 2012 due to steep budgets cuts imposed by the Dutch government and a concomitant change in focus. The last programme broadcast on shortwave was a daily half-hour show in Spanish for Cuba named El Toque (The Touch) on 1 August 2014.Due to government directives, the service implemented a new mandate in 2013 to promote free speech. In 2017, the Ministry of Foreign Affairs altered the organisation's mission, cut the budget by nearly half and made 70% of the staff redundant. RNW Media now works to build digital communities for social change.

Shortwave radio

Shortwave radio is radio transmission using shortwave radio frequencies. There is no official definition of the band, but the range always includes all of the high frequency band (HF), and generally extends from 1.7–30 MHz (176.3–10.0 m); from the high end of the medium frequency band (MF) just above the mediumwave AM broadcast band, to the end of the HF band.

Radio waves in the shortwave band can be reflected or refracted from a layer of electrically charged atoms in the atmosphere called the ionosphere. Therefore, short waves directed at an angle into the sky can be reflected back to Earth at great distances, beyond the horizon. This is called skywave or "skip" propagation. Thus shortwave radio can be used for very long distance communication, in contrast to radio waves of higher frequency which travel in straight lines (line-of-sight propagation) and are limited by the visual horizon, about 64 km (40 miles). Shortwave radio is used for broadcasting of voice and music to shortwave listeners over very large areas; sometimes entire continents or beyond. It is also used for military over-the-horizon radar, diplomatic communication, and two-way international communication by amateur radio enthusiasts for hobby, educational and emergency purposes, as well as for long distance aviation and marine communications.

Subcarrier signals

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