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Longwave

For other uses, see Longwave (disambiguation).

Tuning dial on 1946 Dynatron Merlin T.69 console radio receiver, showing LW wavelengths between 800 and 2000 metres (375–150 kHz)

In radio, longwave, long wave or long-wave,[1] and commonly abbreviated LW,[2] refers to parts of the radio spectrum with wavelengths longer than what was originally called the medium-wave broadcasting band. The term is historic, dating from the early 20th century, when the radio spectrum was considered to consist of longwave (LW), medium-wave (MW), and short-wave (SW) radio bands. 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 intended meaning varies. It may be used for radio wavelengths longer than 1,000 m[2] i.e. frequencies[note 1] up to 300 kilohertz (kHz),[3][4] including the International Telecommunication Union's (ITU's) low frequency (LF, 30–300 kHz) and very low frequency (VLF, 3–30 kHz) bands. Sometimes the upper limit is taken to be higher than 300 kHz, but not above the start of the medium wave broadcast band at 520 kHz.[5]

In Europe, Africa, and large parts of Asia (International Telecommunication Union Region 1), where a range of frequencies between 148.5 and 283.5 kHz is used for AM broadcasting[6] in addition to the medium-wave band, the term longwave usually refers specifically to this broadcasting band, which falls wholly within the low frequency band of the radio spectrum (30–300 kHz). The "Longwave Club of America" (United States) is interested in "frequencies below the AM broadcast band"[5] (i.e., all frequencies below 520 kHz).

  1. ^ Graf, Rudolf F. (1999). Modern Dictionary of Electronics, 7th Ed. Boston MA: Newnes. p. 23. ISBN 0750698667.
  2. ^ a b "long wave". Macmillan Online Dictionary. Macmillan Publishers. Archived from the original on 11 August 2016. Retrieved 20 June 2016.
  3. ^ "long wave". Cambridge Online Dictionary. Cambridge University Press. Archived from the original on 20 August 2016. Retrieved 20 June 2016 – via Cambridge.org.
  4. ^ Graf, Rudolf F. (1999). Modern Dictionary of Electronics (7th ed.). Newnes. p. 437. ISBN 0750698667.
  5. ^ a b "About LWCA". Longwave Club of America. Archived from the original on 27 June 2016. Retrieved 20 June 2016.
  6. ^ Barun Roy (September 2009). Enter The World of Mass Media. Pustak Mahal. p. 21. ISBN 978-81-223-1080-1.


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