An Improved Space-Time Coding Scheme for FMCW MIMO-SAR

Multiple-input multiple-output (MIMO) synthetic aperture radar (SAR) system, as a new SAR system, is expected to improve the performance of interferometric applications, ground moving target indication, wide-swath imaging, and three-dimensional imaging. Effective orthogonal waveform design and echo separation scheme are the key issues in the realization of MIMO-SAR system. Otherwise, the residual ambiguous energy introduced by incomplete separation will degrade the quality of SAR images. However, most schemes are designed for pulsed SAR systems, which are not necessarily compatible with continuous wave systems. This paper proposes an improved space-time coding scheme for FMCW MIMO-SAR, which avoids the performance degradation associated with the time-variant channel responses caused by the motion of the SAR platform. The echo separation performance of the proposed scheme is evaluated and compared with the conventional scheme through simulation experiments.