A Fast Forward Model for Simulating EMI Scattering with Realistic Sensors and Elongated Objects

摘要

Fast solutions for UWB electromagnetic induction (EMI) scattering from fundamental object shapes are of longstanding interest for sensing of metallic objects, e.g. underground unexploded ordnance (UXO) detection and discrimination. Researchers have recently developed the general formulation for an analytical solution for EMI scattering from a spheroid. The specialization based on Small Penetration Assumption (SPA) is designed to attack the high frequency difficulties that challenge many numerical techniques. This paper uses the new analytical techniques to explore scattering from spheroids and other objects, with excitation complicated by non-uniform fields. To perform the necessary decomposition of the transmitted primary field into spheroidal modes, we represent the transmitter by a set of magnetic dipoles, which dramatically increases efficiency. The performance of the SPA solution is evaluated by comparison with results from other numerical techniques and measured data. Comparison with measured data also indicates that EMI signals from some complicated objects can be approximated by those from spheroids with similar proportions, which is promising for applications requiring fast solutions, such as inversion processing.