Abstract
Multiple-input multiple-output (MIMO) synthetic aperture radar (SAR) using stepped frequency (SF) waveforms enables a high two-dimensional (2D) resolution with wider imaging swath at relatively low cost. However, only the stripmap mode has been discussed for SF MIMO-SAR. This paper presents an efficient algorithm to reconstruct the signal of SF MIMO-SAR in the spotlight and sliding spotlight modes, which includes Doppler ambiguity resolving algorithm based on subaperture division and an improved frequency-domain bandwidth synthesis (FBS) method. Both simulated and constructed data are used to validate the effectiveness of the proposed algorithm.
Highlights
According to the minimum antenna area constraint, high resolution and wide swath (HRWS) pose contradicting requirements on synthetic aperture radar (SAR) system design [1]. This system-inherent limitation can be overcome by singleinput multiple-output (SIMO) SAR system [2], which has been extended to multiple SAR modes, such as spotlight and sliding spotlight, to fulfill the different requirements of spatial resolution and coverage in future SAR missions [3,4,5]
The stepped frequency (SF) multiple-input multiple-output (MIMO)-SAR, which is defined as the MIMO-SAR system transmitting and receiving a class of SF subband signals simultaneously by multiple azimuth channels, respectively, combines the advantages of the SIMO system and SF waveforms and enables HRWS imaging at relatively low cost [9, 10]
The azimuth reconstruction processing based on the subaperture division for the sliding spotlight SIMO SAR [4] can be extended to SF MIMO-SAR in the spotlight and sliding spotlight modes to resolve Doppler ambiguity of each subband signal
Summary
According to the minimum antenna area constraint, high resolution and wide swath (HRWS) pose contradicting requirements on synthetic aperture radar (SAR) system design [1]. This system-inherent limitation can be overcome by singleinput multiple-output (SIMO) SAR system [2], which has been extended to multiple SAR modes, such as spotlight and sliding spotlight, to fulfill the different requirements of spatial resolution and coverage in future SAR missions [3,4,5]. An efficient algorithm is presented to reconstruct SF MIMO-SAR signal for the spotlight and sliding spotlight modes.
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