A Technique to Mitigate the Direct and Ground Reflection Signals Effect in Bistatic Subsurface SAR Imaging System

A high resolution 3-D images of underground objects might be achieved using bistatic subsurface synthetic aperture radar (SAR) due the bistatic configuration's ability to view the objects from multiple angles. However, a major obstacle preventing the imaging is the dominance of the direct and ground reflection signals over the scattered signals from the buried objects. This paper presents a technique to mitigate such obstacle. By utilizing the multiple sampling points SAR provides, each adjacent sampling points are processed together as two-element array that has a null along the direction of the direct and ground reflection signals leading to significant enhancement for the scattered signals from the buried objects. The technique is explained and both simulation and measurement results for buried metallic objects are presented as a test of performance.