Channel Error Correction for Ultra-high Resolution Airborne SAR System with Synthetic Bandwidth

Synthetic bandwidth technique provides an effective way to achieve the ultra high range resolution of airborne SAR. But in the real synthetic bandwidth system, the correlation is badly distorted by the phase error. If it is directly synthesized, the result will be seriously deteriorated. In this paper, based on the detailed research of the phase error, an improved Polynomial-Phase Transform (PPT) method is proposed to estimate the phase error from the echo directly. The Fourier Transform (FT) is replaced by the FRactional Fourier Transform (FRFT) in the new method, which can decrease the number of PT to reduce the SNR loss, and the circle amount is half. Theoretical analysis and the raw data prove the proposed approach is effective. Finally, the range resolution down to 0.05 m is obtained.