Calibration of Antennas Phase Imbalance of an FMCW ATI-SAR for Surface Velocity Mapping

Phase matching between receivers of the ATI-SAR system is important for accurate radial velocity measurement since any system induced phase offsets will translate into velocity errors. Previous study has shown that the phase mismatch in the phase responses between receive channels of ATI-SAR should be taken care of and calibrated during SAR processing. This study presents a novel phase calibration approach to mitigate the phase offsets due to phase imbalance between receive antennas' phase pattern in a dual-beam ATI-SAR system. By direct estimation of the antenna phase imbalance with the stationary farmland SAR data, the system phase offsets observed in the ATI-SAR interferogram can be greatly attenuated. This work is important for improving the accuracy of compact low-cost FMCW inter-ferometric SAR system for surface motion detection.