SAR autofocus based on minimum entropy

This paper proposes an autofocus method based on minimum-entropy criterion for synthetic aperture radar imaging. Through minimizing the entropy, an iterative method is derived to obtain the phase error, which corrupts the image and increases the image entropy. In addition, dominant-scatter areas are selected as the input of the phase-error estimation. Note that there is not any model assumption for the phase error and the dominant-scatter area isn´t required to only contain one point scatter. The phase estimation accuracy and efficiency are also analyzed in this paper. Finally, the simulation and experimental results are used to validate the feasibility and effectiveness of the proposed method.