Buried object characterization via ground-penetrating radar and Huynen polarimetric parameters

A known target buried underground and illuminated from the air on its top flat surface by a ground-penetrating radar (GPR) is used to verify the results of a polarization approach that uses the Huynen parameters. The target is a dielectric cylinder of diameter d and height h that simulates a land mine buried in soil, flat top surface looking up. A method-of-moments (MoM) approach (and codes) is used to generate the complex elements of the scattering matrix S of the present target. These elements are obtained in modulus and phase as functions of frequency in the wide band; 0 <= f <= 5 GHz, for various angles of incidence of the radar beam on the air-ground interface. That matrix S is then used to generate the elements of the traditional Mueller matrix M ' by several methods, which are described. The Huynen parameters are then extracted from M ' and the pertinent nonvanishing ones are plotted versus frequency in the same band. This extraction is done with care because Huynen defined his M ' differently than in the traditional fashion-a great source of confusion. After several appropriate changes the results agree with those of earlier works. As confirmation, the values of the Huynen parameters revert and recover the original elements of M ' they are extracted from. The plots of the Huynen parameters for this target indeed give a general phenomenological description of the buried, symmetric object with differences in local curvatures and somewhat irregular structure that was originally conceived. The displayed plots of various nonvanishing elements of M ' and of the Huynen parameters, at normal and oblique incidences verify our conclusions and the method. (c) 2005 Society of Photo-Optical Instrumentation Engineers.