Abstract
A new multiple-input multiple-output (MIMO) synthetic aperture radar (SAR) configuration using multiple contiguous azimuth beams is proposed to map wider image swaths with higher cross-range resolution as compared with the conventional MIMO-SAR. The proposed configuration is independent of the orthogonal waveforms used for transmission and it allows the use of all the phase centers including the overlapping ones to reduce the minimum operating pulse repetition frequency that should be satisfied to avoid aliasing in the azimuth dimension unlike the case of the conventional MIMO-SAR in which only the nonoverlapped phase centers and one of each overlapped phase centers are utilized. This is the result of employing multiple contiguous azimuth beams which makes the echoes, whose effective phase centers are overlapped, occupy different Doppler bandwidths. Each transmitted waveform consists of a sequence of subpulses such that each subpulse is a conventional linear frequency modulated waveform. Echoes corresponding to different phase centers at a given receiver are separated using digital beamforming on receive in elevation. The estimated range profile is free from interrange cell interference as frequency domain system identification-based estimation algorithm is used to identify the impulse response in the range dimension. Finally, both simulated and constructed raw data are used to validate the efficiency of the proposed algorithm.
Highlights
T HE possibility of imaging a high-resolution wide-swath scene using multiple-input multiple-output (MIMO) synthetic aperture radar (SAR) has been first addressed in [1] where the contradicting requirements of having the desired swath width and high cross-range resolution in conventional single-input single-output (SISO) SAR are mitigated [2]– [4]
The following section shows the numerical results of our proposed MIMO-SAR configuration using an linear frequency modulated (LFM) waveform and compares it with a conventional MIMO-SAR
It is due to the multiple contiguous azimuth beams which makes the echoes, whose effective phase centers are overlapped, occupy different Doppler bandwidths
Summary
T HE possibility of imaging a high-resolution wide-swath scene using multiple-input multiple-output (MIMO) synthetic aperture radar (SAR) has been first addressed in [1] where the contradicting requirements of having the desired swath width and high cross-range resolution in conventional single-input single-output (SISO) SAR are mitigated [2]– [4]. Interrange cell interference (IRCI)-free multiple subband MIMO-SAR is proposed in [7] where multiple narrow receiving beams with multiple phase centers are used This configuration has an advantage that the echoes corresponding to different transmitted subband waveforms are processed simultaneously at the receiver without a need to separate them. The minimum PRF in the proposed configuration should satisfy the inequality PRF ≥ Bd/(M × N ) which provides the opportunity to map wider image swaths with higher cross-range resolution as compared with the conventional MIMO SAR
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