Efficient Synthesis of Antenna Pattern Using Improved PSO for Spaceborne SAR Performance and Imaging in Presence of Element Failure

For a synthetic aperture radar (SAR) system, the individual beam pattern pointing and shaping due to amplitudes and phase settings in transmit/receive modules (TRMs) are mainly used in the elevation direction over the total range of incidence angles. The criteria for the optimized antenna elevation beam pattern are profoundly linked to the overall SAR system performance requirements. In particular, a high sidelobe level (SLL) in the antenna pattern leads to a high range ambiguity-to-signal ratio (RASR), which degrades the quality of the SAR image. RASRs can be controlled by appropriate antenna SLL suppression at defined positions in the elevation pattern. This paper focuses on the improvement in the SAR system performance using an effective technique for optimizing antenna pattern synthesis. The desired antenna patterns can be synthesized referring to the optimized antenna mask templates using the newly devised cost function and improved particle swarm optimization (IPSO). Even though there are some defective TRMs in array phased antennas, one can regenerate an optimal pattern as close as possible to the desired one, owing to the proposed cost function and IPSO. Moreover, this paper provides a new perspective on RASR performance, which can be analyzed in SAR images, via the full-chain process from antenna pattern synthesis to SAR image formation. In addition, this is the first study to consider the problem of antenna pattern optimization with element failure, in terms of spaceborne SAR imaging, as well as SAR system performance. The simulations conducted in this study show that the optimized pattern obtained via the proposed technique can provide good SAR system performance, resulting in high-quality SAR images, even with defective TRMs.