Modeling Azimuth Ambiguities in Focused SAR Data

Azimuth ambiguities are an intrinsic characteristic of a Synthetic Aperture Radar (SAR) image caused by aliasing of the Doppler spectrum. This work presents a complete 2D model of the replica's structure regarding power distribution and phase pattern. It is shown that the false target is a smeared version of the true signal, and the dispersion is well predicted by a closed-form model. A deep understanding of such features can assist in retrieving the true signal superposed by aliasing or even in using azimuth ambiguities as an additional source of information. The model was validated by simulation and a real COSMO-SkyMed acquisition. By considering the derived model, it was possible to refocus the ambiguous regions and recover the original targets.