VHF

Very High Frequency (VHF) designates the portion of the radio spectrum between 30 and 300 MHz. Wavelengths range from about 10 meters to 1 meter. The term is used in international spectrum management and by radio services to describe a broad set of bands allocated for civil, commercial, and military use.

Propagation in the VHF range is largely line-of-sight. Signals travel directly between transmitter and receiver with limited ground-wave reach and are strongly affected by terrain, buildings, and antenna height. Ionospheric reflection is uncommon, which limits long-range VHF communications compared with lower frequencies.

Common uses include air traffic control and aircraft communications, marine radio, land-mobile and public-safety networks, and broadcast services such as FM radio (88–108 MHz). In addition, many amateur radio bands operate in the VHF range, notably around 50–54 MHz (6 meters), 144–148 MHz (2 meters), and 420–450 MHz (70 centimeters).

Equipment and operation: VHF systems typically use line-of-sight antennas and equipment designed for relatively narrow bandwidths. Communications often employ frequency modulation (FM) for noise resilience, though digital and other modulation schemes are increasingly used, especially in professional and amateur networks.

Regulation and licensing: VHF allocations are managed by national authorities under international agreements coordinated by the ITU. Access to many VHF services requires licensing or authorization, with channel plans and power limits intended to minimize interference between different users.