MIMO SAR in High-Resolution Wide-Swath Imaging
This chapter discusses mainly multiple-input multiple-output (MIMO) Synthetic aperture radar (SAR) potential and challenges in high-resolution wide-swath remote sensing. Efficient SAR imaging techniques should provide high-resolution imagery over a wide area of surveillance, but it is a contradiction due to the minimum antenna area constraint. The illuminated area must be restricted, so as to avoid ambiguous returns. MIMO SAR provides potential solutions to resolving the disadvantages of conventional single-antenna SAR in high-resolution wide-swath remote sensing. There are two kinds of general MIMO SAR configuration, single phase center multibeam (SPCM) and multiple phase center multibeam. In the SPCM MIMO SAR, a distinct channel is associated with each of the receiving beams and, hence, the data are split according to azimuth angular position or, equivalently, instantaneous Doppler frequency center in the azimuth direction. One of the main advantages of MIMO SAR is that the degrees-of-freedom can be greatly increased by the concept of virtual array provided by the multiple antennas.