Definition
An electromagnetic wave whose oscillation rate falls within the range used for radio communication and navigation, broadly from about 3 kilohertz (kHz) to 300 gigahertz (GHz). In aviation, specific RF bands are assigned to specific functions — VHF for voice communications, UHF for DME and transponders, and so on.
Plain English
A radio signal — the invisible wave that carries voice, navigation data, or equipment signals through the air between an aircraft and a ground station or another aircraft.
Context Anchor
Seen in avionics, navigation, and DME discussions when describing the signals sent between the aircraft equipment and the ground station.
Derivation
From 'radio' (Latin radius, meaning ray or beam) and 'frequency' (how often something repeats). Together: how rapidly the radio wave's energy cycles per second. Faster cycles mean a higher frequency.
Why Pilots Care
Correct radio frequency selection is required to talk to ATC and receive usable navigation signals.
Intuition Check
RF does not mean the sound you hear in a headset. It means the radio energy carrying the signal before the equipment turns it into information you can use.
Example Sentence 1
The DME transmits and receives on UHF radio frequencies, even though the pilot tunes it through a paired VHF nav frequency.
Example Sentence 2
DME interrogates the ground station on a UHF radio frequency paired with the VOR channel.