An effective algorithm for subsurface SAR imaging

For many applications in subsurface sensing (e.g., landmine detection or road inspection), it is important to make images of the shallow subsurface from the data acquired by a GPR with antennas slightly elevated above the ground. Classical SAR algorithms are not well suited to this purpose. A new SAR algorithm in the space-time domain for a multi-media propagation environment is proposed. In comparison with known algorithms, this algorithm is significantly simplified without loss of accuracy. The simplifications are based on a physical analysis of the sensing wave propagation. We also show that, for a multi-media background, it is not possible to determine correctly the depth of a scatterer and the speed of light in the ground from only one B-scan without additional information about the transverse position of the scatterer.