beam

A radio beam is a focused transmission of radio waves, often used in navigation and radar systems. In point-to-point communication, directional antennas concentrate radio waves into a narrow beam to direct signals toward a specific receiver. This is distinct from omnidirectional antennas that broadcast signals widely.1

Radio range beacons, developed in the early 20th century, used directional loop antennas to create specific flight paths, or "beams," for aircraft. These systems marked preferred courses, and deviations from the beam would disrupt a steady tone heard by the pilot, indicating their position relative to the intended path. While early systems used Morse code characters to define these beams, modern navigation systems like VOR and Instrument Landing System (ILS) use more sophisticated methods to guide aircraft with greater precision.2