Beacons and their purpose
Beacons are radio transmitters used to monitor the propagation of radio signals. Mainly Radio Amateurs use radio beacons on their frequencies. Beacons on microwaves can also be used to balance antennas and receivers.
The IARU and its member societies coordinate beacons on HF, VHF and microwaves established by radio amateurs.
The International Amateur Radio Union (IARU) is a federation of national associations of certified radio amateurs, representing over 150 countries and separate territories around the world.