Moving Target Artifacts in Bistatic Synthetic Aperture Radar Images

Synthetic aperture radar (SAR) imaging methods are designed to image stationary scenes. Moving targets appear smeared and misplaced in reconstructed SAR images. This paper presents a theory to quantitatively analyze and predict positioning errors due to moving targets in bistatic SAR imagery. We derive closed-form, parametric equations between the target velocities and positioning errors in reconstructed images. The analysis is applicable to scenarios involving bistatic configurations and arbitrary imaging geometries including arbitrary antenna trajectories, target velocities, and nonflat topography. We present examples for specific geometric configurations including straight linear trajectories and short and long apertures in bistatic configurations. The predictive equations offer the potential capability to extract moving target signatures, estimate target motion parameters, and form focused bistatic SAR images in complex imaging geometries.