Electromagnetic Induction Response Of A Target Buried In Conductive And Magnetic Soil

Soils that are conductive or magnetic or both can adversely affect the operation of induction metal detectors widely used to detect buried landmines. Although this effect has been known for a long time, it is only recently that efforts to rigorously characterize and quantify it has been initiated. The work reported in this paper is a part of on-going studies to clarify which properties of soil are important and to what extent they affect the performance of metal detectors which operate on the principle of electromagnetic induction. The electromagnetic response of a buried small metallic sphere is analyzed and computed. The results are used to investigate the influence that electrical conductivity and magnetic susceptibility of the host soil have on the signal produced by a target and hence on its detectability by a metal detector. The burial medium is modelled as a half-space. While soil electrical conductivity has been assumed to be real and independent of frequency, its magnetic susceptibility has been modelled as complex and frequency-dependent in general. Results include three specific cases of practical importance, namely, non-conducting soil with constant susceptibility, non-conducting soil with frequency-dependent susceptibility and non-magnetic soil with constant conductivity.