Phase Imbalance Estimation for Azimuth Multi-Channel ScanSAR System

The new concept of combining the azimuth multichannel synthetic aperture radar (SAR) system with the Scan mode was put forward to meet the requirements of future developments in high-resolution and ultrawide-swath SAR design. However, the phase imbalance between channels is inevitable, which will greatly reduce the quality of the image. This article proposed an approach of phase imbalance estimation for azimuth multichannel ScanSAR system. For this, the particularity of the target Doppler spectrum in Scan mode is analyzed firstly. Then, the theoretical derivation reveals the equivalence of scene ambiguity and Doppler spectrum ambiguity. Subsequently, the main idea of the proposed approach is to determine the index of the ambiguous component of the target in the Doppler spectrum by the sparse recovery method. The equivalent multichannel ScanSAR real measured data experiment demonstrates the effectiveness of the proposed approach. Compared with the estimation results of the signal subspace comparison method, the proposed method shows better performance. Finally, the details in the implementation process of the proposed algorithm are described by combining theoretical analysis with simulation experiments.