Plain English Meaning

A simple radio station on the ground that sends out a signal in every direction. An aircraft receiver locks onto that signal and shows the pilot which direction the station is from the airplane, so the pilot can fly toward or away from it.

Full Definition

A ground-based, low- or medium-frequency radio transmitter that radiates a signal equally in all directions, used as a navigation aid by aircraft equipped with an Automatic Direction Finder (ADF). The aircraft's ADF receiver senses the bearing to the station, and the pilot uses that bearing to navigate to or from the beacon, fly approaches, or .