Detection, Localization, and Characterization of Static Magnetic-Dipole Sources

Abstract

This chapter describes methods for finding and identifying isolated magnetic sources, primarily within the context of a magnetic-dipole source model. Sources sought by means of magnetic sensors typically are composed of ferromagnetic materials, principally alloys of iron. In such materials, the volume magnetization exhibits extremely complicated behavior including both a permanent component and an induced component that varies with an externally imposed magnetic field. The localization of magnetic sources is an obvious goal of any application of magnetic sensors. The locations of the dipoles within the source may be prescribed from known concentrations of magnetic material within the source, or may be assigned in an arbitrary way over the space occupied by source. To evaluate magnetic sensor detection capability against dipole sources in the presence of noise, concept of matched-filter detection is useful. A stationary tensor gradiometer co-located with a vector magnetometer can be used to localize a passing dipole source and determine its moment vector on a point-by-point basis.