To evaluate the amplitude vs offset response of GPR to small distributions of hydrocarbon contamination, I acquired multi-offset 450 MHz GPR data in TE and TM modes over a buried rectangular tank filled with gasoline saturated sand. All dimensions of the tank were less than one wavelength at the characteristic antenna frequency. The permittivity ratio at the moist sand/gasoline sand boundary, estimated by fitting the Fresnel equations to the observed amplitudes and by Brewster's Angle analysis, differed from that obtained through migration velocity analysis by no more than 12%. 2D FDTD modeling reproduced amplitude characteristics for 3 o f 4 target/polarization combinations and explained some deviations from the Fresnel curves. Additional deviations may be caused by out-of-plane polarization effects or heterogeneity not included in the 2D model.
©2010 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE. DOI: 10.1109/ICGPR.2010.5550196
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