In a series of previous papers, analytical results dealing with the effects of soil electromagnetic properties on the performance of induction metal detectors were reported. In this paper experimental data are provided to verify some previously reported results. The time-domain response of a magnetic soil half-space and a small metallic sphere situated in air as well as buried in the soil were measured using a purpose-designed system based on a modified Schiebel AN19/2 metal detector. As in the previous work, the sphere is chosen as a simple prototype for the small metal parts in low-metal landmines. The soil used was Cambodian "laterite" with dispersive magnetic susceptibility, which serves as a good model for soils that are known to adversely affect the performance of metal detectors. The metal object used was a sphere of diameter 0.0254 m made of 6061-T6 aluminum. Experimental data are in good agreement with theoretical predictions. Data also show that for the weakly magnetic soil used in the experiments, the total response of the buried sphere is the sum of the response of the soil and that of the sphere placed in air. This finding should simplify the prediction or measurement of response of buried targets as one can separately measure/compute the response of an object in air and that of the host media and simply add the two. This simplification may not be possible for soils that are more strongly magnetic.

Date Published: 7 May 2007
PDF: 12 pages
Proc. SPIE 6553, Detection and Remediation Technologies for Mines and Minelike Targets XII, 655306 (7 May 2007); doi: 10.1117/12.717939

Published in SPIE Proceedings Vol. 6553:
Detection and Remediation Technologies for Mines and Minelike Targets XII
Russell S. Harmon; J. Thomas Broach; John H. Holloway Jr., Editor(s)