LAUSR

Hybrid and $\pm \pi /4$ quadrature-polarimetric (quad-pol) synthetic aperture radar (SAR) systems are established to simultaneously obtain all polarimetric components, including co-polarized (co-pol) and cross-polarized (cross-pol) components. However, the cross-pol components always suffer from severe azimuth ambiguities. In this article, the hybrid and $\pm \pi /4$ quad-pol SAR systems with double receive channels are widely investigated to suppress the azimuth ambiguities of cross-pol components, in which the systems allow for a half pulse repetition frequency but at the cost of antenna size. We firstly provide a more thorough analysis for the double-channel (DC) hybrid and $\pm \pi /4$ quad-pol SAR systems. Then, an improved reconstruction method is proposed to suppress the extremely severe azimuth ambiguity caused by the general reconstruction algorithms. However, the cross-pol signals still exist severe azimuth ambiguity. To this end, the displaced-phase-center antenna (DPCA) condition based on digital beamforming reflector antenna is employed, in which the undesired polarized signal can be greatly suppressed. Furthermore, numerical analysis is developed to demonstrate the excellent performance of the DC hybrid and $\pm \pi /4$ quad-pol SAR systems with such DPCA condition. Finally, the distributed scene simulation results are presented to verify the advantage of the proposed approach.