Definition
The radio frequency band from 30 to 300 kilohertz (kHz). In aviation, LF is used by certain non-directional beacons (NDBs) and a small number of long-range navigation aids, because signals in this band follow the curvature of the earth and travel long distances over land and water.
Plain English
A range of low radio frequencies — between 30 and 300 thousand cycles per second — used by some older navigation beacons that broadcast over long distances.
Context Anchor
Seen in aviation radio, navigation, and signal descriptions, especially when discussing older or ground-based radio systems.
Derivation
Frequency' comes from the Latin frequentia, meaning 'a crowding' or 'how often something repeats.' In radio terms, it means how many wave cycles pass each second. 'Low' here is relative to the full radio spectrum — LF sits well below the frequencies used for VHF voice and VOR navigation.
Why Pilots Care
These signals travel long distances and follow the Earth's curvature, supporting navigation over water or remote terrain where higher-frequency signals are blocked.
Intuition Check
Low Frequency does not mean a weak signal. It means the radio wave repeats at a lower rate than higher-frequency radio waves.
Example Sentence 1
The NDB on the chart transmits in the LF band, so the signal carries well over the coastal route.
Example Sentence 2
LF signals remain usable when flying far from land where other navigation frequencies fade.