Discrimination of subsurface targets with a plane of symmetry using polarimetric bistatic radar

The so called vampire signature effect introduced by Baum [I][2] whereby the monostatic backscattered fields measured from a point on the target symmetry plane exhibit no cross-polarized response in the far field is extended to the case of bistatic measurements in the near field. The principle is applied to GPR in a series of polarimetric SAR measurements to differentiate between buried landmines, which are generally geometrically symmetric, and random clutter, which is generally asymmetric. A method is proposed to utilize the vampire signature as a feature to enhance GPR images to achieve landmine detection. The method is applicable to targets that possess one or more planes of symmetry when both transmit and receive antennas are located on the symmetry plane. Experimental results taken in a controlled sand-box environment are shown to verify the proposed method and the receiver operating characteristic (ROC) for the method is shown.