Index on Radar Systems
Over The Horizon Radars
By using a very low-frequency band these antennas often have huge dimensions. This has the advantage, however, that the propagation of the electromagnetic waves (ground wave) adapts to the curvature of the Earth. Therefore exceptionally good maximum ranges are achieved.
The strategic importance of such radars has decreased since the possibility of observation by satellites. These radar sets are still in use in local coastal defense and research into ocean currents and wave movements.