Near-field wide-band 2-D and 3-D radar imaging using an extended chirp scaling algorithm

This paper presents a new near-field 3-D synthetic aperture radar (SAR) imaging algorithm. This algorithm is an extension Of the 2-D chirp scaling algorithm (CSA). First, the original formulation of the CSA has been extended to the 3-D case. Then, some processing steps have been reformulated in order to incorporate additional terms (up to n-th order) in the approximations assumed by the algorithm. These extra terms are required to maintain the accuracy of the method in the so-called near-field conditions (large coherent integration angle and/or high bandwidth-to-center-frequency ratio). but do not entail a significant increase of the computation time. Tile algorithm has been also optimized for stepped-frequency radars. The performance of the method has been illustrated with numerical simulations and experiments.