Resolution Enhancement in High Resolution Wide Swath MIMO SAR

A new multiple-input multiple-output (MIMO) SAR configuration using multiple adjacent azimuth beams is proposed to map wider image swaths with higher cross-range resolution in comparison with the conventional MIMO SAR. The proposed configuration allows the use of all the phase centres including the overlapping ones to reduce the minimum operating pulse repetition frequency (PRF) unlike the case of the conventional MIMO SAR in which only the non-overlapped phase centres and one of each overlapped phase centres are utilised. The waveforms used for transmission share the same bandwidth and have the same centre frequency. Each transmitted waveform consists of a sequence of sub-pulses consisting of conventional linear frequency modulated (LFM) waveforms and the echoes corresponding to different phase centres are separated at the receiver using digital beamforming (DBF) on receive in elevation. The estimated range profile is free from inter-range cell interference (IRCI) as a frequency domain system identification (FDSI)-based estimation algorithm is used to identify the impulse response in the range dimension. Finally, simulated data is used to validate the effectiveness of the proposed configuration.