Influence of dispersive soil electromagnetic properties on hand-held time domain electromagnetic sensors

Although metal detectors remain the workhorses of humanitarian demining, it is well established that the performance of both continuous wave (frequency domain) and pulsed induction (time domain) detectors can be severely compromised by so-called soil-effects'. Generally, problem soils reduce the signal-to-noise ratio and increase the false-detection rate. In certain locations, the soil-effect is so severe as to render the detector practically inoperable. The current study is part of an ongoing international effort to establish and quantify the influence of soil electromagnetic properties on the operation of metal detectors and related sensor technologies. In particular, we examine the relative influence of soil electrical conductivity, magnetic susceptibility and associated frequency dependence on the time domain electromagnetic (TDEM) response of pulsed induction metal detectors and related small-scale TDEM sensors.