Shortwave radio

"Shortwave" redirects here. For other uses, see Shortwave (disambiguation).
Grundig Satellit 400 solid-state, digital shortwave receiver, c. 1986[1]

Shortwave radio is radio transmission using radio frequencies in the shortwave bands (SW). There is no official definition of the band range, but it always includes all of the high frequency band (HF), which extends from 3 to 30 MHz (100 (exactly 99.930819333) to 10 (exactly 9.9930819333) meters); above the medium frequency band (MF), to the bottom of the VHF 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 communication over very long distances, 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).

Tesla Máj 623A, Short-long-medium wave tube receiver from Czechoslovakia, c. 1956/57

Shortwave broadcasts of radio programs played an important role in the early days of radio history. In World War II it was used as a propaganda tool for an international audience. The heyday of international shortwave broadcasting was during the Cold War between 1960 and 1980.

With the wide implementation of other technologies for the distribution of radio programs, such as satellite radio and cable broadcasting as well as IP-based transmissions, shortwave broadcasting lost importance. Initiatives for the digitization of broadcasting did not bear fruit either, and so as of 2024, few broadcasters continue to broadcast programs on shortwave.

However, shortwave remains important in war zones, such as in the Russo-Ukrainian war,[2][3][4][5][6] and shortwave broadcasts can be transmitted over thousands of miles from a single transmitter, making it difficult for government authorities to censor them. Shortwave radio is also often used by aircraft.

  1. ^ Cite error: The named reference SWRad_GS400 was invoked but never defined (see the help page).
  2. ^ "Why the BBC World Service's New Ukrainian Shortwave Service Matters". The Rand Blog. March 25, 2022.
  3. ^ "Ukraine: BBC adds two shortwave broadcasts, NEXUS adds MW service". The SW Ling Post. February 25, 2022. Retrieved December 4, 2023.
  4. ^ "BBC World Service 15735 AM 1400 utc 25 Feb 2022 - new transmission". HF Underground. February 25, 2022. Retrieved December 4, 2023.
  5. ^ "BBC World Service 5875 kHz Shortwave Russia Ukraine War broadcast". YouTube. March 2, 2022. Retrieved December 4, 2023.
  6. ^ Demianyk, Graeme (2 March 2022). "BBC Revives Old-School Radio Service To Help Ukraine As TV And Internet Attacked". HuffPost UK. Retrieved 11 December 2023.