Sidelobe Leakage Reduction in Random Phase Diversity Radar Using Coherent CLEAN

Random pulse-to-pulse phase diversity provides the means to suppress range-ambiguous interference in medium-to-high pulse repetition frequency radar applications. However, Doppler filters used in random phase diversity processing tend to suffer from high average sidelobe levels. This paper shows how this problem can be addressed using Coherent CLEAN, a deconvolution algorithm originally developed to address the problem of sidelobe interference in sparse antenna arrays. In the context of random phase diversity, Coherent CLEAN can remove sidelobe leakage from the output of a random phase diversity Doppler filter bank or be applied more directly to disentangle returns from multiple range ambiguities. The algorithm is proposed as an effective and computationally efficient feasible alternative to iterative filter refinement or “worst-case” filter shaping for suppression of unexpected returns. Multiple modes of applying Coherent CLEAN are described and a new variation of the algorithm, simultaneous Coherent CLEAN, is introduced.