Three-dimensional steerable magnetic field antenna for metal target classification

ABSTRACT This paper describes a prototype three-dimensional electromagnetic induction (EMI) sensor system that has the potential to measure directly the multiple components of buried metal targets’ magnetic polarizability tensor without the need to invert spatial data from single-axis EMI sensors. This novel sensor is called a three-dimensional steerable magnetic field (3DSMF) sensor system. The 3DSMF sensor is a high-time resolution, wide-bandwidth time-domain EMI system combined with a 3-axis magnetic field generator (3AMFG) and magnetic field receivers. The 3AMFG differs from previous 3-axis magnetic field generators in a number of ways: the projected magnetic field is relatively uniform in space and is steerable. These two features offer the potential to greatly improve target classification. This paper discusses the 3DSMF sensor system design philosophy and modeling results. Keywords: Electromagnetic induction, unexploded ordnance, metal detection, classification, metal discrimination