The broadcast medium wave band now extends above the 200 m / 1,500 kHz limit.Įarly long-distance radio telegraphy used long waves, below 300 kilohertz (kHz). Shortwave radio received its name because the wavelengths in this band are shorter than 200 m (1,500 kHz) which marked the original upper limit of the medium frequency band first used for radio communications. The name 'shortwave' originated during the beginning of radio in the early 20th century, when the radio spectrum was divided into long wave (LW), medium wave (MW), and short wave (SW) bands based on the length of the wave. Radio amateurs carried out the first shortwave transmissions over a long distance before those of Guglielmo Marconi. However, shortwave remains important in war zones, such as in the Russo-Ukrainian war, and shortwave broadcasts can be transmitted over thousands of miles from a single transmitter, making it difficult for government authorities to censor them. Initiatives for the digitization of broadcasting did not bear fruit either, and so as of 2022, few broadcasters continue to broadcast programs on shortwave. 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. The heyday of international shortwave broadcasting was during the Cold War between 19. In World War II it was used as a propaganda tool for an international audience.

Shortwave broadcasts of radio programs played an important role in the early days of radio history. 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). This is called skywave or 'skip' propagation.

Therefore, short waves directed at an angle into the sky can be reflected back to Earth at great distances, beyond the horizon. Radio waves in the shortwave band can be reflected or refracted from a layer of electrically charged atoms in the atmosphere called the ionosphere. There is no official definition of the band, but the range always includes all of the high frequency band (HF), which extends from 3 to 30 MHz (100 to 10 metres) above the medium frequency band (MF), to the bottom of the VHF band. Shortwave radio is radio transmission using shortwave (SW) radio frequencies. Grundig Satellit 400 solid-state, digital shortwave receiver, c. 1986

Grundig radio clock