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Non-iterative GPR imaging through a non-planar air-ground interface

It is often advantageous to acquire pulse-echo ground penetrating radar (GPR) measurements from antennas that are offset from a non-planar air-ground interface by a non-negligible distance, either because the ground surface is rough, or because measurements must be collected remotely. To compensate for a non-planar air-ground interface, a modification of the plane-to-plane backpropagation algorithm is formulated for surface variations that are relatively smooth with respect to the radar waveform wavelengths. To facilitate this method, a technique for inferring the surface topography from the radar returns is developed. Finally, examples are given to demonstrate the improvement offered over other non-iterative imaging techniques.