Motion Compensation Algorithm Based on Entropy-Minimization for Terahertz SAR

Compared with microwave synthetic aperture radar (SAR), terahertz SAR (THz SAR) is easier to achieve ultrahigh-resolution image but more difficult to compensate motion errors. For the reason that there are more motion errors to be considered in THz SAR, in addition to the low-frequency phase errors (LPEs) in conventional microwave SAR, the high-frequency phase errors (HPEs) caused by tiny high-frequency vibration of the platform must be handled prudently. To compensate all kind of motion errors simultaneously, this paper starts from the defocused image, proposes a non-parametric compensation algorithm based on entropy-minimization, which does not make any hypothesis of the phase error. Newton method is used to implement optimal search of phase error. Finally, the effectiveness of the proposed algorithm is demonstrated by simulation results.