THz-SAR Oriented Rotation Parameter Estimation Based on Time-Frequency Analysis

Strengths of terahertz synthetic aperture radar (THz-SAR) in high-resolution radar imaging and fine-grained target recognition have been widely proven. However, rotating targets existing in the scene will cause the defocus or ghost of the final result, which is not conducive to the subsequent image interpretation. To eliminate this adverse effect, it is necessary to accurately estimate rotation parameters. Taking special spectral characteristics of rotating targets into consideration, this paper extracts the signal of interest (SoI) from adopts the coarse focused result. Then, the inverse Radon transform of the time-frequency (TF) is applied to estimate the amplitude and the initial phase coarsely. Finally, both parameters can be searched and determined accurately according to the upper and lower envelop of TF distribution. Simulation results validate the feasibility and accuracy of the proposed method.