Distortion in the ISAR (inverse synthetic aperture radar) images from moving targets

A physics-based numerical model has been developed to model the formation of severe distortion that is observed in ISAR images from moving targets. When a target possesses a small time-varying perturbed motion, a modulation effect is introduced in the phase of the radar return from the target. As a result, a broad smearing appears in the cross-range of the ISAR image. An experiment is devised to demonstrate that significant distortion can occur in the ISAR image when a small perturbing motion is imposed on a target. The measured data are also used to validate the simulated results from the model. Excellent agreement is obtained between the simulated and measured ISAR images. The numerical and experimental studies described in this paper provide a better understanding of the distortion mechanism in ISAR imaging of moving targets.