GPR ATTENUATION AND ITS NUMERICAL-SIMULATION IN 2.5 DIMENSIONS

Modeling of ground-penetrating radar (GPR) data in 2.5 dimensions is i mplemented by superposition of 2-D finite-difference, time-domain solu tions of Maxwell's equations for different horizontal wavenumbers. Die lectric, magnetic, and conductive losses are included in a single form ulation. Attenuations associated with dielectric and magnetic relaxati ons are introduced by superposition of Debye functions at a set of rel axation frequencies and using memory variables to replace convolutions between the field variables and the decay functions. Better fits to d ata may always be obtained using the superposition method than by the Cole-Cole model. Good fits to both loss-tangent versus frequency data from lab measurements, and to 500 and 900 MHz held GPR profiles of a b uried pipe and the surrounding layers, demonstrate the flexibility and viability of the modeling algorithm. Discrepancies between lab and in -situ measurements may be attributed to scale differences and local va riations that make lab samples less representative of the site than th e GPR profile.