Joint approach of translational and rotational phase error corrections for high‐resolution inverse synthetic aperture radar imaging using minimum‐entropy

In high‐resolution inverse synthetic aperture radar (ISAR) imaging, the rotational motion of the targets tends to introduce the time‐variant Doppler modulation in the echo, which acts as the range‐variant phase errors in the phase history. Moreover, the performance of translational phase error correction may be dramatically degraded without properly considering the range‐variant phase errors. In this study, a joint approach of translational and rotational phase error corrections is introduced into high‐resolution ISAR imaging. In the procedure, the joint phase error correction is modelled as that of range‐invariant and range‐variant phase errors using a metric of minimum entropy. Then, the minimum‐entropy optimisation is solved by employing a coordinate descend method based on quasi‐Newton solver. In comparison of the conventional methods, the proposed approach in this study promises a better performance of phase error correction with a higher efficiency. Finally, experiments based on simulated and measured data are performed to confirm the effectiveness of the proposed algorithm.