Enhancement of Azimuth Focus Performance in High-Resolution SAR Imaging Based on the Compensation for Sensors Platform Vibration

The high-frequency vibration of radar sensors platform, whose influence is generally negligible in traditional synthetic aperture radar (SAR) imaging, has a significant influence on the high-frequency band, such as the terahertz (THz) band SAR imaging. In this paper, the high-frequency vibration of sensors platform model of THz SAR imaging is established and the effect of it is analyzed. For the vibration of platform can be viewed as a simple harmonic motion, the received signal of THz SAR in each range bin can be considered as sinusoid frequency modulation (SFM) signal. This will cause the images to be defocused in the azimuth processing. A novel algorithm for the parameters estimation of SFM signal based on the discrete sinusoid frequency modulation transform is proposed in this paper, and the simulated annealing algorithm is used to reduce the computational load simultaneously. Then, the phase errors induced by the sensors platform vibration can be compensated by the estimated parameters. The numerical results demonstrate the effectiveness of the novel algorithm proposed in this paper.