Longwave
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The longwave radio band is the range of frequencies approximately lying between 12 and 1000 kHz[1] (corresponding to wavelengths between 20000 and 250 metres respectively), although the term also applies to subsets of this range (for example commercial longwave broadcasting is understood to range from 148.5 and 283.5 kHz, i.e. wavelengths between 2000 and 1000 metres).
This range encompasses the low-frequency (LF) band (30 kHz–300 kHz).
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[edit] Band propagation characteristics
Longwave signals 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 and less severe interference-caused fadeouts. Instead, the D-layer of the ionosphere and the surface of the earth serve as a waveguide directing the signal[citation needed].
[edit] Historical significance
Essentially all radio transmitters before 1924 were longwave transmitters[citation needed]. Propagation of shorter wavelengths was not understood until the shortwave experiments by amateur radio operators in 1923 and by Marconi in 1924. Spark-gap transmitters were used prior to World War I, until the development of powerful Radio alternators by General Electric just prior to the war. Vacuum tubes began to be used to generate radio frequencies in the mid-1920s.
After 1924, use of longwave radio for long distance communication began to decline, as much less expensive shortwave transmitters began to carry increasingly heavy volumes of long distance communication. A period of explosive growth of shortwave communications began in 1927, leading to rapid decline in longwave radio usage.
[edit] Broadcasting
In Europe, North Africa, Russia and Mongolia (ITU Region 1), longwave radio frequencies in the band 148.5 to 283.5 kHz are used for domestic and international broadcasting. Carrier frequencies are multiples of 9 kHz ranging from 153 to 279 kHz. There are two exceptions in Germany, where two stations are offset by 3 kHz either side of 180 kHz. Historically LW stations operated on frequencies as high as 413 kHz (although the highest carrier frequency currently in use for LW broadcasting is 279 kHz). Some stations derive their carrier frequencies from an atomic clock. It can be therefore used as frequency standard.
Several countries transmitted radio programming over power lines or telephone lines using LW frequencies. These systems were known variously as Linjesender, Telefonrundspruch or Wire Broadcasting however these systems were phased out with the introduction of ISDN and later ADSL and it is believed that there are no longer any in operation[citation needed].
[edit] ITU Region 2 note
In the Americas (ITU Region 2), there is no longwave broadcast band. In North America during the 1970s the longwave frequencies 167, 179 and 191 kHz were used for a short-lived network of civil defence emergency broadcasting stations with stations at Ault, Colorado and Cambridge, Kansas[citation needed], as well as station WGU-20 in Chase, MD.
Nowadays the 160-190 kHz range is used there for Part 15 Lowfers amateur and experimental stations. The 190-435 kHz band is used for navigational beacons.
[edit] List of longwave broadcasting transmitters
List of the most important longwave broadcasting transmitters (Source: http://de.wikipedia.org/wiki/Langwelle and World Radio TV Handbook).
| Frequency | Station name | Country | Location | Aerial type | Power | Remarks |
|---|---|---|---|---|---|---|
| 153 kHz | Deutschlandfunk |  Germany |
Donebach | Directional aerial, two guyed steel lattice masts, 363 m high, fed at the top | 500 kW | Night: 250 kW |
| Radio Romania |  Romania |
Braşov | T-aerial on 2 guyed steel lattice masts with a height of 250 metres | 1200 kW | ||
| NRK Finnmark |  Norway |
Ingoy | Omnidirectional aerial, guyed steel lattice mast of 362 m height, fed at the top, ex-Omega equipment | 100 kW | ||
| Chaine 1 |  Algeria |
Kenadsa / Bechar | Three guyed steel lattice masts, height 357 m. | 2000 kW | ||
| 162 kHz | France Inter |  France |
Allouis | Two guyed steel lattice masts, height 350 m, fed on the top | 2000 kW | Time signal phase-modulated |
| TRT |  Turkey |
Agri | 1000 kW | |||
| 171 kHz | Medi 1 |  Morocco |
Nador | Directional aerial consisting of three guyed steel lattice masts, 380 metres tall | 2000 kW | |
| Radio Rossii |  Russia |
Bolshakovo near Kaliningrad | 600 kW | |||
| Radio Rossii |  Ukraine |
Krasne near Lwow | 150/75 kW | inactive at present | ||
| 177 kHz | Deutschlandradio Kultur | Germany |
Zehlendorf near Oranienburg | Omnidirectional aerial, cage aerial mounted on 359.7 m high guyed mast, triangle aerial on 3 150 m high guyed steel lattice masts | 500 kW | Since August 29th, 2005 between 2 and 5 a.m. CET DRM-Mode
Non-standard frequency (not divisible by 9) |
| 180 kHz | TRT | Turkey |
Polatli | 1200 kW | Turkish Programme | |
| 183 kHz | Europe 1 | Germany |
Felsberg-Berus | Directional aerial, four ground insulated steel lattice masts. Heights of 270 m, 276 m, 280 m and 282 m. Spare aerial: two ground insulated steel lattice masts of 234 m height. | 2000 kW | French progamme. The most Powerful Longwave transmitter in Germany. |
| 189 kHz | RÚV |  Iceland |
Gufuskalar near Hellissandur | Slight oval bi-directivity aerial, top loaded parallel connected triangular loops, mast as a common member, all guys insulated except two radiating diametrically opposed grounded top guys, loops closed by copper straps in the ground from two conducting guy grounding points to base of the guyed steel lattice mast insulated against ground, height 412m | 300 kW | RÚV national programs 1 and 2 Rás 1 and Rás 2 |
| RAI |  Italy |
Caltanissetta | Omnidirectional aerial, guyed steel lattice mast, height 282 m | 10 kW | Inactive since August 2004 | |
| 198 kHz | BBC Radio 4 |  United Kingdom |
Droitwich (SFN) | T-aerial on 2 guyed steel lattice masts insulated against ground with a height of 213 metres | 500 kW | Relays BBC World Service after the end of its own programmes. |
| BBC Radio 4 | United Kingdom |
Burghead (SFN) | Omnidirectional aerial, guyed steel lattice mast | 50 kW | ||
| BBC Radio 4 | United Kingdom |
Westerglen (SFN) | Omnidirectional aerial, guyed steel lattice mast, height 152 m | 50 kW | ||
| Chaine 1 | Algeria |
Berkaoui / Ouargla | Three guyed steel lattice masts. | 2000 kW | ||
| Polskie Radio Parlament/Program 1 |  Poland |
Raszyn | Omnidirectional aerial, guyed steel lattice mast insulated against ground, 335 m high | 500 kW | Only active during the daytime | |
| Radio Majak | Russia |
Sankt Petersburg - Olgino | Omnidirectional aerial, 205 m high guyed steel lattice mast | 150 kW | ||
| 207 kHz | RÚV | Iceland |
Eiðar near Egilsstaðir | Omnidirectional aerial, steel lattice mast insulated against ground, height 220 m | 100 kW | RÚV national programs 1 and 2 Rás 1 and Rás 2 |
| Deutschlandfunk | Germany |
Aholming | Directional aerial, two guyed steel lattice masts, 265 m high, fed at the top | 500 kW | Night: 250 kW | |
| Ukrainian Radio | Ukraine |
Brovary | two guyed steel lattice masts insulated against ground, 150 m high, each equipped with a cage antenna at its lower part | 600 kW | ||
| 216 kHz | Radio Monte Carlo |  Monaco |
Roumoules | Directional aerial, 3 300 metre high guyed steel lattice masts, 330 metre high guyed steel lattice mast as backup aerial | 1200 kW | Transmitter site exterritorial, exclave of Monaco |
| 225 kHz | Polskie Radio Program 1 | Poland |
Solec Kujawski | Directional aerial, 2 guyed radio masts fed on the top, heights 330 m and 289 m | 1000 kW | Earlier transmitter site Konstantynów |
| 234 kHz | RTL |  Luxembourg |
Beidweiler | Directional aerial, 3 guyed grounded steel lattice masts, 290 m high, with vertical cage aerials | 2000 kW | Spare transmitter site Junglinster |
| Radio 1 | Russia |
Krasny Bor transmitter | Omnidirectional aerial, 271.5 metres tall guyed mast with cage antenna | 1200 kW | May be inactive at present | |
| 243 kHz | Danmarks Radio |  Denmark |
Kalundborg | Alexanderson aerial, carried from 2 118 Meter high free-standing steel lattice towers | 300 kW | Stop 15 February 2007 |
| 252 kHz | Chaine 1 | Algeria |
Tipaza | Omnidirectional aerial, single guyed lattice steel mast, height 355 m | 1500 kW | French programme; during night-time half transmitter-power |
| RTÉ Radio 1 |  Ireland |
Clarkestown | Omnidirectional aerial, guyed steel lattice mast, insulated against ground, height 248 m | 500 kW | Now the only AM transmitter for RTÉ Radio 1. Decreases power at night to 100kW. | |
| 261 kHz | Transmitter Burg | Germany |
Burg | Omnidirectional aerial, cage aerial on 324 m high guyed, grounded steel lattice mast, 210 m high steel tube mast, insulated against ground | 200 kW | Inactive at the moment, formerly used by Radio Wolga and Radioropa Info |
| Radio Rossii | Russia |
Taldom | Omnidirectional aerial, central mast, 275 metre tall, surrounded by 5 guyed masts on a circle around | 2500 kW | Most powerful transmitter in the world | |
| Radio Horizont |  Bulgaria |
Vakarel | One of the few Blaw-Knox Towers in Europe, 215m high | 75 kW | ||
| 270 kHz | ČRO 1 - Radiožurnál |  Czech Republic |
Topolna | Directional aerial (maximum of radiation in East-West direction), two grounded 257 m high guyed steel lattice mast with cage aerials | 500 kW | |
| 279 kHz | Belaruskaje Radyjo 1 (BR1) |  Belarus |
Sasnovy | 500 kW | ||
| Radio Mayak (RUS) | Russia |
Yekaterinburg | Omnidirectional aerial, guyed steel lattice mast of 256 m height, fed at the top | 150 kW |
[edit] References
[edit] See also
- Low frequency: for other uses (military, commercial and amateur) of this part of the radio spectrum (30-300 kHz)
- Electromagnetic spectrum: Very low frequency, Shortwave, Groundwave, Skywave
- Radio broadcasting: AM radio, BBC Radio 4, BBC Light Programme, Radio clock, Office de Radiodiffusion Télévision Française, Warsaw radio mast, Digital Radio Mondiale, International broadcasting,
- Shipping: Satellite navigation system, Navigation, Shipping Forecast
- Lists: List of wave topics
- Other: 1 E3 m, National Institute of Standards and Technology, Fail-Safe, WGU-20
[edit] Further reading
- Tomislav Stimac, "Definition of frequency bands (VLF, ELF... etc.)". IK1QFK Home Page.
- The Medium Wave Circle - The premier club for MW/LW enthusiasts
- Medium Wave News - Published regularly since 1954
- Euro-African Medium Wave Guide
- "Longwave Club of America".
- [1] - LF activity of British radio amateur G3XDV
- Klawitter, G.; Oexner, M., Herold, K. (2000). "8.2 Langwellenrundfunk", Langwelle und Längstwelle (in German). Meckenheim: Siebel Verlag GmbH, 116-131. ISBN 3-89632-043-2.
- Busch, Heinrich (2001-11-14), Luftschiff Graf Zeppelin LZ127, <http://www.seefunknetz.de/lz127.htm> (German)
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