A Novel Scheme for Ambiguous Energy Suppression in MIMO-SAR Systems

Attention has been devoted to multi-input multioutput (MIMO) synthetic aperture radar (SAR) systems in recent years. The applications of MIMO-SAR systems which involve high-resolution wide-swath remote sensing, 3-D imaging, and multibaseline interferometry are seriously limited to the orthogonal waveforms. This restriction is mainly caused by the imperfect orthogonal waveform-introduced ambiguous energy. For a single point target, the impact of the ambiguous energy can be neglected. However, when it comes to the spatially distributed scattering scenarios, the ambiguous energy from closely spaced scatterers, which would be accumulated, degrades the SAR image seriously. In order to suppress the ambiguous energy, a novel energy cancellation scheme using the Sequence CLEAN technique in the range direction is proposed in this letter. By employing the proposed novel scheme on the raw data of MIMO-SAR systems, the ambiguous energy from both point and distributed targets can be suppressed. The proposed scheme is validated by simulations and practical experiments.