radio transmission using radio frequencies in the shortwave bands.

thermal radiation in the optical spectrum, including visible, near-ultraviolet, and near-infrared spectra.

Device that uses electromagnetic energy.

frequency allocations for use within the shortwave radio spectrum (the upper medium frequency [MF] band and all of the high frequency [HF] band).

Shortwave listening, or SWLing, is the hobby of listening to shortwave radio broadcasts located on frequencies between 1700 kHz and 30 MHz Listeners range from casual users seeking international news and entertainment programming, to hobbyists immersed in the technical aspects of long-distance radio reception and sending and collecting official confirmations (QSL cards) that document their reception of remote broadcasts (DXing).