A novel ISAR imaging method for multiple targets moving in formation

When multiple targets, such as aircrafts in a formation, fly closely in the same radar beam, the returned signals from these targets are overlapped in time. Therefore, by applying conventional motion compensation algorithms that work well for single target, the multiple targets cannot be resolved and each individual target cannot be clearly image. This paper proposes a novel inverse aperture radar (ISAR) imaging method for multiple targets moving in a formation with uniformly accelerative rectilinear motion. This method is composed of three steps. In the first step, range curvature and range walk are corrected by the acceleration compensation and Keystone transform (KT) respectively. Then, phase adjustment is used to obtain a bulk ISAR image of multiple targets. The second step is the image segmentation that partitions the region of each target by the normalized cuts. Finally, refined compensation using conventional motion compensation algorithm is carried out to obtain a well-focused ISAR image of each individual target. Simulation results prove the effectiveness of the proposed method.