Ground permittivity estimation using radar to ground coupling

Raw Ground Penetrating Radar data provides time of flight information to buried objects, tunnels or natural geological structures. However, to obtain depth in units of distance one must first estimate the ground´s permittivity. Knowledge of the permittivity also allows for increased accuracy of imaging algorithms via inverse scattering and in estimation of target radar cross section/natural resonances. Currently permittivity may be estimated via several methods including the common mid point algorithm, by studying the shape of hyperbolic returns from constrained scatterers by inserting probes, or by extracting soil for laboratory analysis. All of these techniques have disadvantages including the need for antenna arrays, buried objects of known shape, digging and/or additional hardware. Recently work has been performed on using the magnitude of the early time signal (cross talk). The technique proposed in the work at hand relies solely on the frequency shift in the cross talk from the radar´s transmitter to receiver that occurs due to the presence of the ground (dielectric loading). The relationship between permittivity and the frequency shift is modeled mathematically and the model used to measure permittivity. The technique may be applied to any pre-existing ground coupled radar even if nothing is known of the radar´s antennas or feed system.