10 June 2005 Discrimination of UXO buried under magnetic soil
Author Affiliations +
Abstract
Electromagnetic induction (EMI) has become a promising technique for UXO detection and discrimination. In most studies the effect of the ground itself is assumed small and neglected. This assumption holds up relative to ground conductivity and corresponding induced electric currents. However experience shows that magnetic effects may sometimes be significant. Here we consider the case when the ground itself is mildly permeable, a common condition. Magnetic (i.e. permeable) soil could conceivably affect the EMI response of buried metallic targets in three ways: (1) the half space of soil itself produces a scattered field, dependent on the position of the sensor, which becomes part of the background; (2) The incident field that reaches the target and the response that reaches the sensor are altered by the air-ground interface; and (3) the frequency response of the target may be altered by changes in the ratio of its magnetic permeability to that of the ground in which it is buried. Regarding the first factor, analysis shows that the response of a half space to an above-ground dipole source should be flat across the EMI spectrum. By describing our actual sensor in terms of a collection of infinitesimal dipoles, we are thus able to calculate the response due to the ground alone as a function of antenna elevation and tilt. This can then be subtracted from the data as background. Examination of realistic ground parameters at UXO sites and reference to basic magneto-quasistatic solutions allows to discount the effects of the second and third factors. We then construct a forward model which takes the soil effect into account via the first factor, and apply the model in a pattern matching approach for UXO discrimination. Example results show that the effect of soil is important in some cases, and neglecting soil effect may cause quite significant difficulty or error in UXO discrimination.
© (2005) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
K. Sun, K. O'Neill, F. Shubitidze, I. Shamatava, K. D. Paulsen, "Discrimination of UXO buried under magnetic soil", Proc. SPIE 5794, Detection and Remediation Technologies for Mines and Minelike Targets X, (10 June 2005); doi: 10.1117/12.603769; https://doi.org/10.1117/12.603769
PROCEEDINGS
12 PAGES


SHARE
Back to Top