Range Ambiguity Mitigation in SAR With Multimode OAM Beam

Ambiguity is an inevitable challenge in radar imaging. It can be divided into range ambiguity and azimuth ambiguity. Although setting a high pulse repetition frequency (PRF) can avoid azimuth ambiguity, this will aggravate the range ambiguity. This article proposes to eliminate the range ambiguity via utilizing the orbital angular momentum (OAM) technique. By exploiting the orthogonality between multimodes OAM wave, the information from different sub-swaths can be effectively separated and extracted, thus mitigating the range ambiguity phenomenon. The radar system scheme, multi-OAM-mode design, waveform correlation, and range-ambiguity-to-signal ratio performance are investigated in detail. The proposed approach is further compared with other conventional ambiguity suppression methods by numerical simulations to validate the superiority of the proposed method.