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LongwaveLongwave radio frequencies are those below 500 kHz, which correspond to wavelengths longer than 600 meters. They have the property of following the curvature of the earth, making them ideal for continuous, continental communications. Unlike shortwave radio, longwave signals do not reflect or refract using the ionosphere, so there are fewer phase-caused fadeouts. The earliest radio transmitters, including the Alexanderson alternator, were all longwave transmitters. In Europe, North Africa and Asia, longwave radio frequencies between 153 and 279 kHz are used for domestic and international broadcasting. In the Americas, frequencies between 200 and 430 kHz are used for non-directional beacons, and do not necessarily follow the same 9 kHz spacing that other areas do. The frequency of 60 kHz is used by several nations, such as the USA, UK, and Japan, for extremely accurate time and precision frequency signals. (77.5 kHz is used in Germany.) Many commercial appliances (such as self-setting clocks) sold since approximately 2000 have a VLF receiver capable of receiving these signals, which penetrate indoors more effectively than mediumwave or shortwave signals. Radio signals below 50 kHz are capable of penetrating ocean depths to approximately 200 meters. The United States, Russian, British, Swedish, and Indian navies communicate with submarines on these frequencies. In addition, Royal Navy nuclear submarines carrying ballistic missiles are allegedly under standing orders to monitor the BBC Radio 4 transmission on 198 kHz in waters near the U.K. It is rumoured that they are to construe a sudden halt in transmission as an indicator that the U.K. is under attack, whereafter their sealed orders take effect. As aerials are usually used: mast antennas which are fed at the bottom and which are insulated against ground, mast antennas fed by the guy ropes (such masts are usually grounded), T-aerials, L-aerials and long wire aerials. In future the use of Cross-field-antenna is to be expected, if they work. T-aerials and L-aerials are depending on the requirements mounted on as well grounded as insulated masts or towers. The height of aerials differ from usage: for NDBs the height is just around 10 metres, while for more powerful navigation transmitters as DECCA masts with a height around 100 metres are used. T-aerials have a height between 50 and 200 metres, while mast aerials are usually taller than 150 metres. The height of mast aerials for LORAN-C is around 190 metres for such with radiation powers below 500 kW and around 400 metres for such with powers more than 1000 kilowatts. The first type of LORAN-C aerials is insulated against ground. Longwave broadcasting stations use mast antennas with heights of more than 150 metres or T-aerials. The mast antennas can be ground-fed insulated masts or upper-fed grounded masts. It is also possible to use cage aerials on grounded masts. Nearly all longwave aerials are not as high as the quater of the radiated wavelength. The only longwave transmission aerial realized with a height corresponding to the half of the radiated wavelength was Warszaw Radio Mast. For broadcasting stations often directional aerials are required. They consist of multiple masts, which need not to be from the same height. Some longwave aerials consist of multiple mast antennas arranged in a circle with or without a mast antenna in the centre. Such aerials focus the transmitted power toward ground and gave a large zone of fading free reception. Because they are very expensive, they are barely used. One aerial of this kind was used by transmitter Orlunda in Sweden. Longwave transmitting antennas take up large amounts of space, and have been the cause of controversy in the United States and Europe due to fears over proximity to high-power radio waves. List of longwave broadcasting transmitters List of the most important longwave broadcasting transmitters (Source: http://de.wikipedia.org/wiki/Langwelle ). | Frequency | Name of transmitter | Country | Location | Kind of aerial | Power | Remarks | | rowspan=3 valign=top | 153 kHz | Deutschlandfunk | Germany | Donebach | directional aerial, two guyed steel framework masts, 363 m high, fed at the top | 500 kW | night 250 kW | | Radio Romania | Romania | Brasov | | 1200 kW | | | NRK Finnmark | Norway | Ingoy | omnidirectional aerial, guyed steel framework mast of 362 m height | 100 kW | | | 162 kHz | France Inter | France | Allouis | two guyed steel framework masts, height 350 m, fed on the top | 2000 kW | | | rowspan=2 valign=top | 171 kHz | Radio Medi | Morocco | Nador | | 1200 kW | | | Radio Rossiya | Russia | Kaliningrad | | 1200 kW | | | 177 kHz | DeutschlandRadio Berlin | Germany | Zehlendorf near Oranienburg | reusen aerial mounted on 359.7 m high guyed mast, triangle aerial on 3 150 m high guyed steel framework masts | 500 kW | | | 183 kHz | Europe 1 | Germany | Felsberg | directional aerial, 4 insulated guyed steel framework masts, heights: 282 m, 280 m, 26 m and 270 m | 2000 kW | French Program | | 189 kHz | RUV | Iceland | Hellissandur | omnidirectional aerial, guyed steel framework mast, height 412 m | 300 kW | | | 189 kHz | RAI | Italia | Caltanissetta | omnidirectional aerial, guyed steel framework mast, height 282 m | 10 kW | inactive since August 2004 | | rowspan=4 valign=top | 198 kHz | BBC Radio 4 | United Kingdom | Droitwich | T-aerial on 2 guyed steel framework masts with a height of 213 metre | 500 kW | BBC World Service | | BBC Radio 4 | United Kingdom | Burghead | Guyed steel framework mast | 50 kW | | | BBC Radio 4 | United Kingdom | Westerglen | Guyed steel framework mast, height 152 m | 50 kW | | | Radio Polonia | Poland | Raszyn | Guyed insulated mast, 335 m high | 500 kW | only active at daytime | | 207 kHz | Deutschlandfunk | Germany | Aholming | directional aerial, two guyed steel framework masts, 265 m high, fed at the top | 500 kW | night 250 kW | | 216 kHz | Radio Monte Carlo | France | Roumoules | directional aerial, 3 300 metre high guyed steel framework masts, 330 metre high guyed steel framework mast as backup aerial | 1200 kW | Transmitter site exterritorial, exclave of Monaco | | 225 kHz | Radio Polonia | Poland | Solec Kujawski | 2 guyed radio masts fed on the top, heights 330 m and 289 m | 1000 kW | Earlier tranmitter site Konstantynow | | 234 kHz | RTL | Luxemburg | Beidweiler | directional aerial, 3 guyed grounded steel framework masts, 290 m high, with vertikal reusens | 2000 kW | Spare transmitter site Junglinster | | 243 kHz | Danmarks Radio | Danmark | Kalundborg | Alexanderson aerial, carried from 2 118 Meter high freestanding steel framework towers | 300 kW | | | rowspan=2 valign=top | 252 kHz | RTA Algier | Algeria | Tipaza | | 1500 kW | French programme; during nighttime half transmitter-power | | RT Radio 1 | Ireland | Clarkestown | Guyed steel framework mast, insulated against ground, height 248 m | 500 kW | Earlier used by Atlantic 252 and TeamTalk 252 | | rowspan=2 valign=top | 261 kHz | Transmitter Burg | Germany | Burg | Reusen aerial on 324 m high guyed steel framework mast, 210 m high steel tube mast, insulated against ground, omnidirectional radiation | 200 kW | inactive at the moment | | Radio Rossiya | Russia | Taldom | | 2500 kW | Most powerful transmitter in the world | | 270 kHz | ČRO 1 - Radiožurnl | Czech Republic | Topolna | two grounded guyed steel framework mast with reusen aerials, height 257 m, directional radiation with maximum of radiation in East-West direction | 500 kW | | | rowspan=2 valign=top | 279 kHz | Musicmann279 | Isle of Man | 5 km off Ramsey | Crossed field antenna | 500 kW | Tests planned to begin in early 2005 pending a summer 2005 launch | | BR1 | Belarus | Minsk | | 500 kW | | See also - Electromagnetic spectrum: Shortwave, Low frequency, Groundwave, Skywave
- Radio: AM radio, BBC Radio 4, BBC Light Programme, Radio clock, Office de Radiodiffusion Tlvision Franaise, Warsaw radio mast, Digital Radio Mondiale, International broadcasting,
- Shipping: Satellite navigation system, Navigation, Shipping Forecast
- Lists: List of music videos by year, List of wave topics
- Other: 1 E3 m, National Institute of Standards and Technology, Fail-Safe
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