Radio station Radio broadcasting is transmission of audio (sound), sometimes with related metadata, by radio waves to radio receivers belonging to a public audience. In terrestrial radio broadcasting the radio waves are broadcast by a land-based radi ...

s that cannot communicate directly due to distance, terrain or other difficulties sometimes use an intermediate radio relay station to relay the signals. A radio relay receives weak signals and retransmits them, often in a different direction, as a stronger signal. Examples include airborne radio relay, microwave radio relay, and

communications satellite A communications satellite is an artificial satellite that relays and amplifies radio telecommunication signals via a transponder; it creates a communication channel between a source transmitter and a receiver at different locations on Earth ...

. The

American Radio Relay League The American Radio Relay League (ARRL) is the largest membership association of amateur radio enthusiasts in the United States. ARRL is a non-profit organization, and was co-founded on April 6, 1914, by Hiram Percy Maxim and Clarence D. Tuska o ...

was founded for this purpose but did not change its name when this became a less important part of its work.

See also