Surface Radars - Civil and Coastal Radars

Surface Radars are divided into :

• Ground radar ;

• Naval Radars.

Located at a low height above the ground or sea, Surface Radars emit waves that skim the ground or sea, and are reflected not only by the "useful targets" (flying objects, ships, vehicles), but also by a large number of ground (land relief, buildings, vegetation...) or sea (waves, sea spray...) elements, producing the ground or sea "clutter".

The presence of ground or sea clutter, and the low speed of movement of Surface Radars, distinguish them from Airborne or Space Radars.

This results in different design choices, even if the basic principles are the same:

• emission of an electromagnetic wave ;

• reflection of waves on useful targets and on the environment ;

• reception of reflected waves, the "echoes";

• treatment to reveal useful targets and suppress other echoes;

• summary presentation of results to an operator or control center.

On the other hand, Surface Radars are classified according to their technical type:

• Primary radar (watch, tracking, multifunction) ;

• Secondary radar (surveillance, identification).

The combination of a Primary Radar and a Secondary Radar constitutes a "Radar System".

The Radar System benefits from the complementarity between Primary and Secondary Radars. As Primary Radar requires no specific equipment on board the aircraft, it enhances safety by being tolerant of transponder failures, which are essential for Secondary Radar. It also detects non-transponder-equipped aircraft and produces a weather map. Secondary Radar, on the other hand, has the advantage of providing additional information to radar location:

• target identification ;

• altitude measured by on-board altimeter ;

• on-board computer information on flight instructions ;

• it can alert the controller to the aircraft's detection of a potential conflict with a neighboring aircraft that is too close, thus enhancing flight safety.

Thanks to this complementarity, the Radar System ensures both :

• detection and localization of all objects (cooperative and non-cooperative);

• collecting information transmitted...