Stepped Frequency IRCI-Free Sliding Spotlight MIMO SAR

A stepped-frequency sliding spotlight MIMO SAR using frequency domain system identification (FDSI) algorithm is proposed to obtain ultra high resolution radar images with wide swatch coverage. In this paper, a stepped-frequency waveforms are adopted in such a way that each transmitter emits a conventional linear frequency modulated (LFM) waveform modulated by a different carrier frequency and the obtained range resolution corresponds to the total transmitted bandwidth. The proposed method has ideally zero sidelobe level in the estimated channel in the range dimension. In addition, a low PRF is used and the resulted azimuth ambiguity is removed using spatial filters along with azimuth de-ramping.