Radio Direction Finder

A radio direction finder is a device that uses radio waves to determine the direction to a radio source, whether that source is a cooperating transmitter, a naturally occurring radio source, or an illicit or enemy transmitter. Unlike radar, which also reports a distance to the object of interest, a direction finder yields only a bearing from the receiver, though the location of a source can be found by triangulation from two or more direction finding receivers. Radio direction finders are used in radio navigation for ships and aircraft, in locating emergency transmitters for search and rescue, in tracking wildlife, and in locating illegal or interfering transmitters, and during the Second World War both sides used them to locate and direct aircraft, surface ships and submarines. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/