Accurate 3D UWB radar super-resolution imaging for a bi-static antenna configuration

This paper deals with a real-time capable accurate 3D ultra-wideband radar imaging algorithm for complex shaped 3D objects including edges and corners. A well known wavefront based imaging algorithm is adapted to the bi-static 3D scenario which is, in contrast to the popular migration based algorithms, real-time capable and directly gathers the object contour coordinates. In order to reconstruct a accurate 3D object contour, the commonly proposed planar scan track (i.e. the planar aperture) of the antennas is modified and extended to a spatial scanning track with a circumnavigation of the object. To provide a more diverse radar signature the monostatic antenna configuration is extended to a bistatic configuration. Hence, the shape of the radiating wavefront is no longer spherical but ellipsoidal. Consequently, to ensure the super-resolution accuracy, the intersection point of 3 arbitrarily oriented and shifted ellipsoids in the 3 dimensional Euclidean space has to be determined. An iterative solution will be presented which utilizes the Gauss-Newton method to obtain a fast converging estimation with negligible error in the least-square sense. An experimental validation is carried out based on complex test objects with small shape variations relative to the used wavelength, an pseudo noise radar device (from 4.5 GHz to 13.5 GHz) and two tapered slot line Vivaldi antennas.