A Robust Channel Phase Error Calibration Algorithm for Azimuth Multichannel SAR Imaging Based on the Rotation-Invariant Property

In azimuth multichannel synthetic aperture radar (AMC-SAR) systems, channel phase errors can induce ghost targets. The estimation of signal parameters by the rotational invariance technique (ESPRIT) assumes that the principal signal subspace corresponds to the steering vector at zero Doppler frequency. However, this assumption is frequently violated in practice, resulting in performance degradation. To address this issue, a robust ESPRIT (RESPRIT) algorithm is proposed, which integrates initial ESPRIT-based phase error estimation with residual phase error correction through image contrast maximization. Both simulation and real airborne data experiments demonstrate the effectiveness and robustness of the proposed method.