Multipath Suppression in SAR Vehicle Targets Detection Based on Inter-Subaperture Ghost Trajectories

Abstract

In synthetic aperture radar (SAR) imaging, multipath effects between distributed targets generate spurious targets with strong scattering characteristics, known as “multipath ghosts,” which severely interfere with target detection and significantly increase the false alarm rate. Addressing the limitations of existing methods that rely on large accumulation angles or complex a priori scene information, this article proposes a novel image-domain multipath detection and suppression method based on the geometric trajectories of ghosts across subapertures. First, a multipath effect model for distributed targets is established, revealing that ghost positions vary systematically with the radar observation angle. Through simulations, the trajectories of multipath ghosts under different observation angles are derived, demonstrating that they form regular curves, such as Cassini ovals and hypocycloids, in the image plane, whereas real targets do not exhibit such characteristics. Leveraging this distinction, a ghost detection and suppression algorithm is developed: multipath ghosts and their corresponding target scattering pairs are identified by calculating the displacement of connected components and fitting trajectory curves; ghost regions are then suppressed by assigning background intensity values. Experimental results on real SAR data demonstrate that the proposed method accurately detects and effectively suppresses multipath ghosts, offering favorable flexibility and practicality. It provides valuable support for SAR target detection, multipath suppression, and image interpretation.