SAR focusing using multiple trihedrals

A recent circular synthetic aperture radar data collection contained various vehicles and calibration targets placed throughout a 5 km scene. By observing multiple orbits of the radar, the down-range distance measurements to scattering features show noticeable drift on the order of 2 m from orbit to orbit. The large scene contained 14 quad-trihedral calibration targets with radar cross sections that are similar to point targets in the elevation range of the scene. This paper presents an algorithm that uses the quad-trihedrals to generate global range focusing parameters and phase error corrections to the complex range profile. Qualitative and quantitative results show the focusing provides a significant improvement to wide-angle image registration and vehicle target discrimination.