Adaptive attenuation of clutter and jamming for array radar

Minimising clutter breakthrough while adaptively cancelling jamming is a recognised problem for radar, especially for airborne radar where ground clutter is distributed widely in direction and Doppler frequency. By adapting the angular gain of an array independently for each range bin and by adapting both the small and the large scale order of its weight function, it is shown that clutter can be reduced to levels well below what is possible for a conventional antenna and that the advantage remains when jamming is cancelled at the same time. Separating the spatial adaption into processes for different spatial scales enables the weights for an array of several thousand elements to be calculated with a numerical workload similar to that for a sub-arrayed radar, but with improved clutter suppression ultimately deriving from access to signals from individual array elements. The arguments are illustrated by simulations for an airborne radar operating in a high pulse repetition frequency mode