THz ISAR Imaging of Space Target with Vibration Compensation

In spatial situational awareness (SSA), Terahertz (THz) inverse synthetic aperture radar (ISAR) includes the characteristics of high-resolution imaging and all-day operation. However, compared with low-frequency ISAR, micro vibrations of space targets can cause images defocusing in THz band. Commonly, the existing vibration compensation algorithms performed time-frequency analysis on the echo data. Then, the vibration phase error was obtained and compensated. However, these techniques are limited to the prominent scattering point and are unable to address the intricate non-linear vibration of the space target. In response to this problems, an THz ISAR imaging framework with non-rigid vibration compensation is proposed. First, a compressed sensing (CS) model is developed to correct for phase error in ISAR imaging due to vibration. Subsequently, the alternating direction method of multipliers (ADMM) is leveraged to optimize the CS model. It is important to note that the ISAR imaging algorithm is transformed into a 2D matrix form in order to reduce memory usage and improve computational efficiency. Finally, measured data is leveraged to validate the superiority of the proposed algorithm, demonstrating the potential of ISAR imaging for practical space targets.