Surface-search radar

A surface search radar, sometimes more accurately known as a sea-surface search radar or naval surveillance radar, is a type of radar intended primarily to locate objects on the surface of lakes and oceans. They are widely found on ships and even small pleasure craft, in which case they are so common that they are more commonly known simply as marine radar. They are also widely used on maritime patrol aircraft and naval helicopters. When mounted on an aircraft, they are often known by the British terminology, Air-to-Surface Vessel radar, or ASV for short.

As with conventional surveillance radars, the radio signal from the radar transmitter reflects off objects, especially metal, and is picked up by a receiver unit. The range of a surface search radar is greatly increased due to several aspects of the sea surfaces and the objects in it. In low sea states, water makes an excellent reflector for radio signals, which helps maximize the signal strength as reflections off the water strike the targets in addition to the line-of-sight signal. Additionally, as the sides of ships generally rise vertically from the surface, objects form partial corner cubes which increases the returned signal. Offsetting these advantages is the fact that large waves also form the same signals, making radar clutter a significant problem.

References

• "Naval Electrical Engineering Training Series: Neets". United States Navy.