Time-Domain Response of a Metal Detector to a Target Buried in Soil with Frequency-Dependent Magnetic Susceptibility


  1. Das, Y.
Corporate Authors
Defence R&D Canada - Suffield, Ralston ALTA (CAN)
The work reported in this paper is a part of on-going studies to clarify how and what extent soil electromagnetic properties affect the performance of induction metal dectectors widely used in humanitarian demining. This paper studies the specific case of the time-domain response of a small metallic sphere buried in a non-conducting soil half-space with frequency-dependent complex magnetic susceptibility. The sphere is chosen as a simple prototype for the small metal parts in low-metal landmines, while soil with dispersive magnetic susceptibility is a good model for some soils that are known to adversely affect the performance of metal detectors. The included analysis and computations extend previous work which has been done mostly in the frequency domain. Approximate theoretical expressions for weakly magnetic soils are found to fit the experimental data very well, which allowed the estimation of soil model parameters, albeit in an ad hoc manner. Soil signal is found to exceed target signal (due to an aluminum sphere of radius 0.0127m) in many cases, even for the weakly magnetic Cambodian laterite used in the experiments. How deep a buried target is detected depends on many other factors in addition to the relative strength of soil and target signals. A general statement cannot thus be made regarding detectability of a target in soil based on the presented results. However, computational results complemented with experimenal data extend th understanding of the effect that so
Report Number
DRDC-SUFFIELD-SL-2006-001 — Scientific Literature
Date of publication
01 Apr 2004
Number of Pages
Hardcopy;Document Image stored on Optical Disk

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