Beam (Navigation)

(radio Navigation):The beam is a descriptive term which refers to an invisible path produced by radio signals. An aircraft can follow the beam when going to or from a navigational fix. The term beam became popular with the four-course, low-frequency radio range that projected four clearly defined beams, or courses, from each of the transmitting stations. When a pilot was flying an aircraft along one of these courses, he was said to be on the beam.