Extension of the 3-D range migration algorithm to cylindrical and spherical scanning geometries

A near field three-dimensional (3-D) synthetic-aperture radar (SAR) algorit hm specially tailored for cylindrical and spherical scanning geometries is presented. An imaging system with 3-D capability can be implemented by usin g a stepped-frequency radar which synthesizes a two-dimensional (2-D) apert ure. Typical scanning geometries commonly used are planar, cylindrical, and spherical. The 3-D range migration algorithm (RMA) can be readily used wit h a planar scanning geometry. This algorithm is extremely accurate, preserv es the phase, and corrects for the wavefront curvature. The RMA cannot be d irectly applied with nonplanar scanning geometries. However, as an alternat ive solution, we propose to backpropagate the backscattered data onto a pla nar aperture in the vicinity of the measurement aperture and then apply the 3-D RMA. The proposed imaging algorithm is validated both numerically and experimentally.