Abstract: The synthetic aperture radar (SAR) signatures of moving target are the basis of ground moving target detection, imaging and relocation. This article develops and analyses the response of polar format algorithm (PFA) to the moving target from the range migration correction point of view, and reveals the principle concerning how the range interpolation and azimuth interpolation correct the range migration for moving target in polar format transformation. The analytical results indicate that PFA not only produces focused image of stationary target, but also eliminates the effects of linear range migration for all the moving targets regardless of their unknown velocity. Therefore, the moving targets with only radial motion will also be well focused by PFA processing when the wavefront curvature can be neglected. Finally, the analytical results are verified via simulation data processing, which indicate that as an imaging pretreatment method, PFA has a wide application prospect.

Key words: synthetic aperture radar, polar format algorithm, SAR/GMTI, range migration correction, keystone transform