Subspectrum Division-Based Imaging Method for Curvilinear Moving Target in Terahertz SAR

Airborne terahertz (THz) synthetic aperture radar (SAR) exhibits unique potential for ground-moving target imaging (GMTIm), due to its high-frame rate and high-resolution capabilities. However, the short wavelength of THz waves significantly increases Doppler sensitivity. When a ground-moving target performs curvilinear motion, such as turns, velocity inconsistencies among scattering points induce variations in Doppler centroid frequencies, and chirp rates, leading to defocusing and geometric deformation. To address these issues, an effective curvilinear moving target refocusing method is proposed in this letter. First, a localized phase gradient autofocus (LPGA) method is employed to compensate for Doppler chirp rate inconsistencies. Second, the additional spatial-domain information from a dual-channel system is utilized to correct geometric deformation. Finally, both simulated and measured data are analyzed to validate the effectiveness of the proposed method.