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Proceedings Paper

Broadband electromagnetic induction response form conducting and permeable spheroids
Author(s): Chi-On Ao; Henning Braunisch; Kevin O'Neill; Jin Au Kong; Leung Tsang; Joel Tidmore Johnson
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Paper Abstract

Broadband electromagnetic induction (EMI) methods are promising in the detection and discrimination of subsurface metallic targets. We compute EMI responses from conducting and permeable spheroids by using a field expansion method which is based on the separation of variables in spheroidal coordinates. In addition to an exact formulation which utilizes the vector spheroidal wavefunctions inside the spheroid, we also develop an approximate theory known as the small penetration-depth approximation (SPA). For general permeability, SPA is applicable at high frequency and compliments the exact formulation which breaks down at high frequency. However, when the permeability of the spheroid is large enough, the SPA yields an accurate broadband response. Numerical results for the far-field frequency responses from prolate and oblate spheroids are presented. By neglecting mutual interactions between the spheroids, we also study the broadband EMI response from a collection of spheroids that are randomly oriented and have different sizes.

Paper Details

Date Published: 18 October 2001
PDF: 12 pages
Proc. SPIE 4394, Detection and Remediation Technologies for Mines and Minelike Targets VI, (18 October 2001); doi: 10.1117/12.445459
Show Author Affiliations
Chi-On Ao, Massachusetts Institute of Technology (United States)
Henning Braunisch, Massachusetts Institute of Technology (United States)
Kevin O'Neill, U.S. Army Cold Regions Research and Engineering Lab. (United States)
Jin Au Kong, Massachusetts Institute of Technology (United States)
Leung Tsang, Univ. of Washington (United States)
Joel Tidmore Johnson, The Ohio State Univ. (United States)

Published in SPIE Proceedings Vol. 4394:
Detection and Remediation Technologies for Mines and Minelike Targets VI
Abinash C. Dubey; James F. Harvey; J. Thomas Broach; Vivian George, Editor(s)

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