What is the purpose of a Direction Finder (DF)?

The purpose of a Direction Finder (DF) is to determine the direction from which a radio signal is being transmitted. This capability is particularly useful in aviation for locating and tracking radio beacons, such as VORs (VHF Omnidirectional Range stations) or NDBs (Non-Directional Beacons). By analyzing the phase of the received signal, a DF can help a pilot or an air traffic controller hone in on the source of that signal, allowing for effective navigation and communication.

Using a DF plays a vital role in enhancing situational awareness, especially in areas where GPS signals may be unreliable or unavailable. It can also function as a navigational aid during search and rescue operations by helping locate distress signals. Hence, the primary function of a Direction Finder aligns closely with its ability to accurately identify the direction of a radio signal.