Very High Frequency (VHF)
Very High Frequency (VHF) refers to the radio frequency band from 30 to 300 MHz. VHF is the primary band for civil aviation voice communications (118–137 MHz) and for VOR navigation (108–117.95 MHz). VHF signals are line-of-sight — range is limited by the curvature of the earth and the altitude of the transmitter and receiver.
VHF Range
Approximate VHF range (NM) ≈ 1.25 × √(altitude in feet). At 10,000 ft, VHF range ≈ 125 NM. At sea level, essentially 0 (no line-of-sight coverage from the ground to another ground station far away). This is why minimum reception altitudes (MEA) exist — below MEA, VHF navaid coverage is not guaranteed.