Exploiting coherent multipath for mainbeam jammer suppression

A technique is proposed for the mitigation of jammers that are spatially colocated with targets of interest. Spatial nulling methods are ineffective for these jammers since they cancel the target signal in their attempt to mitigate the interference. The traditional approach to this problem is to integrate for long time periods to boost the signal power and 'burn-through' the mainbeam jammer. However, the long time periods necessary to acquire a single target in this manner occupy a large amount of the available radar resources and drastically reduce the number of targets the system is able to track. The proposed method exploits coherent terrain-reflected jammer multipath energy incident on the radar from other angles to suppress the mainbeam jammer signal. The coherence arises from the fact that the reflected signals are produced by the same source, i.e. the jammer, as the direct-path signal. By exploiting this coherence, the proposed method is able to achieve partial jammer suppression, while maintaining gain on the target, resulting in a reduction in burn-through time requirements.