In radio, longwave refers to parts of the radio spectrum with relatively long wavelengths. The term is a historic one dating from the early 20th century, when the radio spectrum was considered to consist of long, medium and short wavelengths. Most modern radio systems and devices use wavelengths which would then have been considered 'ultra-short'.
In contemporary usage, the term longwave is not defined precisely and its meaning varies across the world. Most commonly it refers to radio wavelengths longer than 1000 meters (frequencies less than 300 kHz), including the ITU's low frequency (LF) (30–300 kHz) and very low frequency (VLF) (3–30 kHz) bands. Sometimes part of the medium frequency (MF) band (300–3000 kHz) is included.
In Europe, Africa and large parts of Asia (ITU Region 1), where a range of frequencies between 148.5 and 283.5 kHz is used for AM broadcasting (in addition to the medium wave band), the term longwave usually refers specifically to this broadcasting band.
The Region 1 longwave broadcast band falls wholly within the low frequency band of the radio spectrum (30–300 kHz). Broader definitions of longwave may extend below and/or above it. In the US, the Longwave Club of America is interested in "frequencies below the AM broadcast band", i.e., all frequencies below 535 kHz. (Lower frequencies correspond to longer wavelengths.)
Non-directional beacons transmit continuously for the benefit of radio direction finders in marine and aeronautical navigation. They identify themselves by a callsign in Morse code. They can occupy any frequency in the range 190–1750 kHz. In North America they occupy 190–535 kHz. In ITU Region 1 the lower limit is 280 kHz.
There are stations in the range 40–80 kHz that transmit time signals to radio clocks. For example:
- WWVB in Colorado on 60 kHz.
- DCF77 in Frankfurt am Main, Germany on 77.5 kHz.
- JJY in Japan on 40 & 60 kHz.
- 66.66 kHz in Taldom transmitter, Russia.
- BPC in Lintong, China 68.5 kHz.
- MSF time and 60 kHz frequency standard transmitted from Anthorn in the UK
Radio controlled clocks receive their time calibration signals with built-in longwave receivers. They use longwave, rather than shortwave or mediumwave, because the distance that a longwave signal travels is nearly constant.
Longwaves travel by groundwaves that hug the surface of the earth, rather than mediumwaves or shortwaves, whose signals can travel as skywaves, ‘bouncing’ off different layers of the ionosphere at different times of day, which makes the time lag different for every signal received. The delay between when the longwave signal was sent from the transmitter (and the coded time was correct) and when the signal is received by the clock (when the coded time is slightly late) depends on the overland distance between the clock and the transmitter and the speed of light through the air, which is also very nearly constant. Since the time lag is essentially the same, a single constant shift forward from the time coded in the signal can compensate for all longwave signals received at any one location from the same time signal station.
In North America during the 1970s the frequencies 167, 179 and 191 kHz were assigned to the short-lived Public Emergency Radio of the United States. Nowadays 136 kHz and the 160–190 kHz range is used in the United States for Part 15 LowFER amateur and experimental stations, and the 190–435 kHz band is used for navigational beacons.
Swedish station SAQ, located at the Varberg Radio Station facility in Grimeton, is the last remaining operational Alexanderson alternator transmitter. Although the station ended regular service in 1996, it has been maintained as a World Heritage Site and makes at least two demonstration transmissions yearly, on 17.2 kHz.
Typically, a larger area can be covered by a longwave broadcast transmitter than a medium-wave one. This is because ground-wave propagation suffers less attenuation due to limited ground conductivity at lower frequencies.
Carrier frequencies are exact multiples of 9 kHz ranging from 153 to 279 kHz, except for a French language station Europe #1 in Germany. This station did keep to correctly spaced channels spacing for 4 months—only 7 years ago—and all Mongolian transmitters are spaced at 10 kHz.
Until the 1970s, some longwave stations in northern and eastern Europe and the Soviet Union operated on frequencies as high as 433 kHz.
Some stations, for instance Droitwich in the UK, derive their carrier frequencies from an atomic clock. They can be therefore used as frequency standards. Droitwich also broadcasts a low bit-rate data channel, using narrow-shift phase-shift keying of the carrier, for Radio Teleswitch Services.
Long distance reception
Because longwave signals can travel very long distances, some radio amateurs and shortwave listeners engage in an activity called DXing. DXers attempt to listen in to far away transmissions, and they often will send a reception report to the sending station to let them know where they were heard. After receiving a report, the sending station may mail the listener a QSL card to acknowledge this reception.
The longest distance over which a longwave signal has been received is 18,451 kilometres (11,465 mi). It occurred on July 27, 2015, when Mike Thayne of England, received Radio NL on 358 kHz from New Zealand. 
List of longwave broadcasting transmitters
List of stations currently operating:
|Freq. (kHz)||Station name||Language||Country||Location||Aerial type||Power (kW)||Coordinates||Remarks|
|153||Radio Antena Satelor||Romanian||Romania||Brașov||T-aerial on 2 guyed steel lattice masts, height: 250 metres.||200||;|
|NRK P1||Norwegian||Norway||Ingøy||Omnidirectional aerial, guyed steel lattice mast 362 m tall, fed at the top, ex-Omega equipment.||100||The transmitter is important for the fishing fleet in the Barents Sea.|
|Chaîne 1||Arabic||Algeria||Kenadsa||Three 357 metres tall guyed masts.||500||Active with very low modulation and power.|
|162||France Inter||French||France||Allouis||Two guyed lattice steel masts, height: 350 m, fed on the top.||1000/2000||;||Time signal phase-modulated.The transmitter is planned to go off air at the end of 2016.|
|164||MNB Radio 1||Mongolian||Mongolia||Ulan Bator||259 metres tall cable-stayed steel truss mast.||500||Broadcasts from 21:00 to 14:00 UTC.|
|171||Médi 1||Arabic and French||Morocco||Nador||Directional aerial consisting of three guyed steel lattice masts, 380 metres tall.||1600||; ;|
|183||Europe 1||French||Germany||Felsberg-Berus||Directional aerial, four ground insulated steel lattice masts 270 m, 276 m, 280 m and 282 m tall. Spare aerial: two ground insulated steel lattice masts, height: 234 m.||2000||Main antenna:; ; ; , Spare antenna: ;||DRM tests after 00:00 UTC.|
|189||RÚV Rás 1/RÚV Rás 2||Icelandic||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|
|198||BBC Radio 4||English||United Kingdom||Droitwich (SFN)||T-aerial on 2 guyed steel lattice masts insulated against ground with a height of 213 metres.||500||;||All four transmitters carry Radio teleswitch PSK data. Droitwich relays BBC World Service from 01:00 to 05:20 UTC.|
|Burghead (SFN)||Omnidirectional aerial, guyed steel lattice mast, height 154 m.||50|
|Westerglen (SFN)||Omnidirectional aerial, guyed steel lattice mast, height 152 m.|
|Dartford Tunnel (SFN)||0.004|
|207||RÚV Rás 1/RÚV Rás 2||Icelandic||Iceland||Eiðar near Egilsstaðir||Omnidirectional aerial, steel lattice mast insulated against ground, height 221 m.||100|
|SNRT Al Idaâ Al-Watania||Arabic||Morocco||Azilal Demnate||304.8 metres tall guyed mast||400|
|209||MNB Radio 1||Mongolian||Mongolia||Choibalsan||Cable-stayed steel truss mast, height: 275.84 metres||75||Broadcasts from 21:00 to 14:00 UTC.|
|Dalanzadgad||Broadcasts from 21:00 to 14:00 UTC.|
|Olgii||Omnidirectional antenna, 352.5 metres high guyed mast||30||Broadcasts from 21:00 to 14:00 UTC.|
|216||Radio Monte Carlo Info||French||Monaco||Roumoules||Directional aerial, 3 300 metre high guyed steel lattice masts, 330 metre high guyed steel lattice mast as backup aerial.||700/1400||; ; , Backup antenna:||Transmitter located in France. In operation from 5:30 to 23:00 CET.|
|225||Polskie Radio Jedynka||Polish||Poland||Solec Kujawski||Directional aerial, 2 guyed radio masts fed on the top, heights 330 m and 289 m.||1000||Earlier Konstantynów was used ( )|
|227||MNB Radio 1||Mongolian||Mongolia||Altai||Cable-stayed steel truss mast.||75||Broadcasts from 21:00 to 14:00 UTC.|
|234||RTL||French||Luxembourg||Beidweiler||Directional aerial, 3 guyed grounded steel lattice masts, 290 m high, with vertical cage aerials.||1500/2000||; ;||Spare transmitter site Junglinster ( ; ; )|
|243||DR Langbølge||Danish||Denmark||Kalundborg||Semi-directional Alexanderson antenna 153/333 degrees, two grounded 118 m steel lattice radiating towers with interconnecting top wire capacitance.||50||;||Transmitting in time slots only.|
|252||Chaîne 3||Arabic||Algeria||Tipaza||Omnidirectional aerial, single guyed lattice steel mast, height 355 m.||750/1500||Half transmitter power during night.|
|RTÉ Radio 1||English||Ireland||Clarkstown||Omnidirectional aerial, guyed steel lattice mast, insulated against ground, height 248 m.||100/300||The only AM transmitter for RTÉ Radio 1. Power is decreased at night to 100 kW. It is tentatively scheduled to cease broadcasting on May 1, 2017.|
|270||ČRo Radiožurnál||Czech||Czech Republic||Topolná||Directional aerial (maximum of radiation in East-West direction), two grounded 257 m high guyed steel lattice mast with cage aerials.||50||;||Broadcasting from Monday to Friday 5:00-24:00 CET and 6:00-24:00 CET at weekends.|
|279||BR Pershy Kanal/BR Radyjo Stalitsa||Belarusian||Belarus||Sasnovy||353.5 metres tall guyed mast||500|
|TR1 Watan Radio||Turkmen||Turkmenistan||Ashgabat||Cable-stayed steel truss mast||150|
List of stations that have closed or are otherwise inactive:
|Freq. kHz||Station name||Country||Location||Aerial type||Power kW||Coordinates||Remarks|
|Deutschlandfunk||Germany||Donebach||Directional aerial, two guyed steel lattice masts, 363 m high, fed at the top||500||;||closed|
|YuFM||Russia||Taldom transmitter||Omnidirectional aerial, guyed steel lattice mast of 257 m height||300||closed|
|Radio Rossii||Popova near Komsomolsk-na-Amure||1200||closed|
|162||TRT Radyo 4||Turkey||Agri||Two guyed lattice steel masts, height 250 m||1000||;||inactive|
|Radio Tashkent 1||Uzbekistan||Tashkent||150||closed|
|Radio Rossii||Russia||Norilsk||Omnidirectional antenna, 205 m high antenna||150||?||closed|
|Radio Yuldash, Radio Rossii||Ufa||closed|
|Voice of Russia||Russia||Oktyabrsky||257 m metres tall antenna.||1200||closed|
|Radio Rossii||Russia||Bolshakovo near Kaliningrad||Omnidirectional antenna, 257 m high guyed lattice steel mast with cage antenna ( ARRT-antenna)||600||closed|
|Radio Ukraine 1||Ukraine||Krasne near Lwów||Omnidirectional antenna, 259 m high guyed lattice steel mast with cage antenna ( ARRT-antenna)||150/75||inactive|
|Radio Rossii||Russia||Raduga||Omnidirectional antenna, 255 m high guyed lattice steel mast with cage antenna ( ARRT-antenna)||250||closed|
|Radio 1||Russia||Murmansk||Omnidirectional antenna, 257 m high guyed lattice steel mast with cage antenna ( ARRT-antenna)||150||closed|
|Radio 1||Russia||Noginsk||Omnidirectional antenna, 242 m high guyed lattice steel mast with cage antenna ( ARRT-antenna)||150||closed|
|Radio 1||Russia||Ezhva near Syktyvkar||Omnidirectional antenna, 257 m high guyed lattice steel mast with cage antenna ( ARRT-antenna)||150||closed|
|Radio Rossii||Russia||Tulagino near Yakutsk||Omnidirectional antenna, circle antenna with 1 central and 6 ring masts||150||; ; ; ; ; ;||closed|
|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||closed|
|180||TRT Radyo 2||Turkey||Polatli||Omnidirectional antenna, 250 m high guyed latice steel mast||1200||inactive|
|Radio Rossii||Russia||Yelizovo near Petropavlovsk-Kamchatskiy||Omnidirectional antenna, 255 m high guyed lattice steel mast||150||closed|
|Radio Mayak||Russia||Kruchina near Chita||Omnidirectional antenna, 200 m high guyed lattice steel mast||150||inactive|
|Kazakh Radio 1||Kazakhstan||Alma-Ata||250||closed|
|Rai Radio 1||Italy||Caltanissetta||Omnidirectional aerial, guyed steel lattice mast, height 282 m||10||closed|
|Sveriges Radio P1||Sweden||Orlunda||300||closed|
|Radio Rossii||Russia||Kostantinogradovka near Blagoveshchensk||Omnidirectional aerial, 257 m high guyed lattice steel mast with cage antenna ( ARRT-antenna)||1200||closed|
|Polskie Radio Parlament/Radio Polonia||Poland||Raszyn||Omnidirectional aerial, guyed steel lattice mast insulated against ground, 335 m high||200||closed|
|Radio Mayak||Russia||Saint Petersburg - Olgino||Omnidirectional aerial, 205 m high guyed steel lattice mast||150||inactive|
|Radio Mayak||Russia||Angarsk||Before 2001: T-antenna spun between 2 205 m tall guyed steel lattice mast||250||, possibly||closed|
|Radio Mayak||Russia||Avsyunino||Omnidirectional antenna, 257 m high guyed lattice steel mast with cage antenna ( ARRT-antenna)||150||inactive|
|Kyrgyzstan||Krasnaya Rechka near Bishkek||150||closed|
|RNE Radio 5||Spain||Logroño||Directional antenna, 300 metres tall.||>100||closed|
|Radio Ukraine 1||Ukraine||Brovary||Omnidirectional antenna, 259.6 m high guyed lattice steel mast with cage antenna ( ARRT-antenna)||600||closed|
|Jordan Radio||Jordan||Al Karanah||?||;||closed|
|Radio Mayak||Russia||Tynda||Omnidirectional aerial, steel lattice mast insulated against ground, height 244 m||150||closed|
|Deutschlandfunk||Germany||Aholming||Directional aerial, two guyed steel lattice masts, 265 m high, fed at the top||500||;||closed|
|NRK P1||Norway||Lambertseter near Oslo||200||closed|
|Radio Rossii||Russia||Krasnoyarsk||Omnidirectional antenna, guyed lattice steel mast, 210 m tall||150||closed|
|Radio Rossii||Russia||Atamanovka||Directional antenna||150||closed|
|Radio Rossii||Russia||Birobidzhan||2 guyed masts, 260 m high||30||;||closed|
|225||TRT GAP||Turkey||Van||Omnidirectional antenna, 250 m high guyed lattice steel mast||600||inactive|
|Radio Rossii||Russia||Surgut||Omnidirectional antenna, 257 m high guyed lattice steel mast with cage antenna ( ARRT-antenna)||1000||closed|
|Libya||Yafran near Tripoli||1000||closed|
|Radio 1||Russia||Krasny Bor transmitter near Sankt-Peterburg||Omnidirectional aerial, 271.5 metres tall guyed mast with cage antenna||1200||closed|
|Radio Rossii||Russia||Koskovo near Murmansk||Omnidirectional aerial, 210 m tall guyed mast||250||inactive|
|Radio 1||Russia||Novosemeykino near Samara||Four 205 metres tall towers insulated against ground arranged in a square||2000||; ; ;||closed|
|Radio Rossii||Russia||Raduzhnyy near Magadan||Omnidirectional aerial, 259 m high guyed lattice steel mast with cage antenna ( ARRT-antenna)||1000||closed|
|Radio Rossii||Russia||Odinsk near Irkutsk||Omnidirectional aerial, 259 m high guyed lattice steel mast with cage antenna ( ARRT-antenna)||500||closed|
|Radio 1||Russia||Koskovo near Arkhangelsk||Omnidirectional aerial, 257 m high guyed lattice steel mast with cage antenna ( ARRT-antenna)||500||closed|
|243||TRT Radyo 4||Turkey||Erzurum||Omnidirectional antenna, 185 m high guyed lattice steel mast||200||inactive|
|Radio Rossii||Russia||Razdolnoye near Ussuriysk||Omnidirectional antenna, 259 m high guyed lattice steel mast with cage antenna ( ARRT-antenna)||1000||closed|
|Kazakh Radio 1||Kazakhstan||Karaganda||Omnidirectional aerial, guyed steel lattice mast of 254 m height||1000||closed|
|Kazakh Radio 2||Kazakhstan||Alma-Ata||1000||closed|
|Yle Radio 1||Finland||Lahti||200||,||closed|
|Radio Rossii||Russia||Kazan||Omnidirectional aerial, 152 m high guyed lattice steel mast with cage antenna ( ARRT-antenna)||100||closed|
|261||Radioropa Info||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||inactive|
|Radio Rossii||Russia||Taldom||Omnidirectional antenna, circle antenna with 1 central and 5 ring masts, height of central mast 275 m||2500||; ; ; ; ;||closed|
|Radio Rossii||Russia||Kruchina near Chita||Omnidirectional antenna, guyed lattice steel mast, 260 m high||150||closed|
|Radio Rossii||Russia||Tyumen||Omnidirectional antenna, guyed lattice steel mast, 220 m high||150||closed|
|Radio Rossii||Russia||Vorkuta||Omnidirectional antenna, guyed lattice steel mast, 220 m high||50||closed|
|Radio Horizont||Bulgaria||Vakarel||One of the few Blaw-Knox Towers in Europe, 215 m high||75||closed|
|Radio Rossii||Russia||Orenburg||Omnidirectional aerial, guyed steel lattice mast of 137 m height||25||closed|
|Radio 1||Russia||Khabarovsk||2 guyed steel lattice masts, height: 164 m||150||;||closed|
|Radio Rossii||Russia||Gorno-Altaisk||Omnidirectional antenna, 143m high guyed lattice steel mast||50||closed|
|Radio Rossii||Russia||Selenginsk||Omnidirectional aerial, 260 m high guyed lattice steel mast with cage antenna (ARRT-antenna)||150||closed|
|Radio Rossii||Russia||Vestochka near Yuzhno-Sakhalinsk||Omnidirectional antenna, guyed lattice steel mast, 258 m high||1000||closed|
|Radio Rossii||Russia||Yekaterinburg||Omnidirectional aerial, guyed steel lattice mast of 256 m height, fed at the top||150||closed|
- 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, Ground wave, Skywave, Medium wave
- Radio broadcasting: AM broadcasting, BBC Radio 4, BBC Light Programme, Radio clock, Office de Radiodiffusion-Télévision Française, Warsaw radio mast, Digital Radio Mondiale, International broadcasting,
- Shipping: Global navigation satellite system, Navigation, Shipping Forecast
- Lists: Index of wave articles
- Other: 1 kilometre, National Institute of Standards and Technology, Fail-safe, WGU-20
Notes and references
- "long wave". Cambridge Online Dictionary. Cambridge Univ. Press, UK. 2011. Retrieved December 29, 2012. External link in
- "long wave". MacMillan Online Dictionary. MacMillan Publishers. 2009. Retrieved December 29, 2012.
- Graf, Rudolf F. Graf (1999). Modern Dictionary of Electronics, 7th Ed. US: Newnes. p. 437. ISBN 0750698667.
- The World Book Dictionary. US: World Book, Inc. 2003. p. 1232. ISBN 0716602997.
- "About LWCA". Longwave Club of America. Retrieved 2010-01-05.
- SAQ Transmission. Radiostation Grimeton SAQ. Retrieved April 5, 2015.
- Ground-wave propagation curves for frequencies between 10 kHz and 30 MHz. ITU-R Recommendation P.368-9
- Guide to Broadcasting Stations (17th ed.). Butterworth. 1973. p. 18. ISBN 0-592-00081-8.
- de:Langwellenrundfunk[better source needed]
- World Radio TV Handbook
- 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
- How to receive DRM from Kalundborg longwave station
- Reception of long wave and very long wave with ferrite antennas 5-50 kHz
- Klawitter, G.; Oexner, M.; Herold, K. (2000). "8.2 Langwellenrundfunk". Langwelle und Längstwelle (in German). Meckenheim: Siebel Verlag GmbH. pp. 116–131. ISBN 3-89632-043-2.
- Busch, Heinrich (2001-11-14). "Luftschiff Graf Zeppelin LZ127". (German)
- European and Asian Longwave Stations - Medium Wave Radio
- List of long- and mediumwave transmitters with GoogleMap-Links to transmission sites