Locating signals through directional antennas.

(ARDF, also known as radio orienteering, radio fox hunting and radiosport) an amateur racing sport that combines radio direction finding with the map and compass skills of orienteering.

High-frequency direction finding, usually known by its abbreviation HF/DF or nickname huff-duff, is a type of radio direction finder introduced in World War II.

Doppler radio direction finding, also known as Doppler DF, is a radio direction-finding method that generates accurate bearing information with minimal electronics.