Electromagnetic Modeling Using a Thin‐Sheet Approximation for Non‐Sheet‐Like Targets

Abstract

We have studied the applicability of a thin-sheet modeling program for interpretation of electromagnetic responses over non-sheet-like targets. Various sheet orientations were used, such as horizontal, vertical and combinations of horizontal and vertical sheets. Procedures for choosing the number of sheets and deciding how to arrange them in the simulation model have been developed. An aluminum sheet in a model tank was used to verify the thin-sheet modeling code. Thin-sheet modeling also worked well for (1) simulating the response of a rectangular brick-like model using a vertical sheet combination along strike; (2) simulating the response of a square brick-like model using either horizontal or vertical sheets; (3) interpreting magnetic-field ellipticity data over a 55gallon metal barrel in a physical model and over a concrete pipe containing conductors near the top and bottom of the pipe. Thin-sheet modeling is a fast and effective method for simulation of electromagnetic responses. This study shows that thin-sheet modeling is applicable to far more than just thin targets. We have successfully modeled fairly complex 3D bodies with various combinations of thin sheets. We found that the primary restriction on the thin-sheet algorithm for these models is that the induction number in the background medium must be less than one.