Azimuth ambiguity analysis of multi-channel SAR after Doppler reconstruction

For multi-channel synthetic aperture radar (SAR), Doppler reconstruction method could suppress azimuth ambiguities to overcome the contradiction between wide swath and high resolution imaging. The reconstruction method deals with main-lobe aliasing, while side-lobe spectra still exist and are weighted by filter weightings. When the system matrix is ill-conditioned, the un-recovered ambiguities are severely amplified. Considering the matrix inversion method, we derive an explicit expression of the azimuth ambiguity to signal ratio (AASR) by exploiting a Vandermonde component of the system matrix. As the Vandermonde component is Doppler independent, the derived AASR will benefit multi-channel SAR design and performance analysis. With simulated multi-channel SAR data, we illustrate and analyze the ambiguity suppression performance based on the Vandermonde decomposition.