Effects of Soil Electromagnetic Properties on Metal Detectors

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Authors
  1. Das, Y.
Corporate Authors
Defence R&D Canada - Suffield, Ralston ALTA (CAN)
Abstract
This paper presents an analysis, based on existing work in geophysics and nondestructive testing, of the effects of soil electromagnetic properties on the functioning of metal detectors widely used to detect buried landmines. The host soil is modeled as a half-space having real and frequency-independent electrical conductivity but frequency-dependen complex magnetic susceptibility. The analysis technique has been applied to three examples of soil of practical importance, namely, nonconducting soil with frequency-independent susceptibility, nonconducting soil with frequency-dependent susceptibility, and nonmagnetic soil with constant conductivity. Simplifications are made to clearly explain a number of previous field and experimental observations, for example, the greater influence of magnetic properties than of electrical conductivity on the performance of metal detectors. Results also show that soil magnetic properties affect continuous wave and pulsed-induction detectors differently. The effect that electrical conductivity and magnetic susceptibility of the host soil have on the signal produced by a target is investigated by computing the response of a buried small metallic sphere. Computations show that in some cases, which could represent practical landmine detection scenarios, the sifnal from the soil can dominate that due to the target, making it hard to detect the target. Further, it is shown that magnetic soil can alter a target's spectral response, which implies that
Report Number
DRDC-SUFFIELD-SL-2005-177 — Scientific Literature
Date of publication
01 Jun 2006
Number of Pages
10
DSTKIM No
CA027609
CANDIS No
525642
Format(s):
Hardcopy;Document Image stored on Optical Disk

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