Definition
Radio direction finding is the technique of determining the direction from which a radio signal is being transmitted, by using a directional antenna and a receiver to identify the bearing to the signal source relative to the receiving station or aircraft.
Plain English
A method of figuring out which direction a radio signal is coming from, so you can work out where the transmitter is.
Context Anchor
Seen in older radio navigation discussions, emergency transmitter searches, and maintenance references to radio navigation equipment.
Derivation
Straightforward English: 'radio' (the signal type), 'direction' (which way), and 'finding' (locating). The term describes exactly what the equipment does — finds the direction of a radio source.
Why Pilots Care
Helps locate radio beacons or distress signals during navigation or search operations.
Intuition Check
RDF does not mean the radio finds your full position by itself. It tells direction to or from a signal source; distance and exact position require other information.
Example Sentence 1
The search aircraft used radio direction finding to home in on the signal from the downed plane's emergency locator transmitter.
Example Sentence 2
RDF allowed the crew to home in on the beacon during the approach.