Frequency and azimuthal variations of radar cross-section and their influence upon low frequency SAR-imaging

Low-frequency SAR requires a very long aperture length to give a good spatial resolution. As a result, the azimuth angle of the target is varying significantly along the synthetic aperture. The signal bandwidth to carrier frequency ratio is also much larger compared with conventional SAR operating at microwave frequencies, giving a varying target response over the frequency band occupied by the transmitted signal. In this paper, the variations of the radar response with respect to frequency and observation angle and their effects upon SAR-imaging are analyzed for Mie-scattering spheres and flat plates. The results show that the image resolution is significantly influenced by these factors.