Azimuth estimation in periodic linear sparse array by modified amplitude comparison monopulse radar

Estimation of direction of arrival (DOA) of a radar backscatter signal by means of an amplitude comparison monopulse estimation scheme (ACMES) is a common high precision technique. But due to spatial undersampling in a sparse array architecture the conventional ACMES results in azimuth ambiguity. In this paper it is proposed that azimuth ambiguity due to sparse array can be mitigated by replacing the sum beam in ACMES with a flat-top beam while keeping the difference beam unchanged. This approach was adapted and simulated for a naval HF Surface Wave Radar (HF SWR) with an array sparsely distributed among 4 mobile platforms each with a dense 9 element primary array. For a single target scenario the results confirm that the proposed approach achieves a precise angular estimate using a periodic sparse linear array.