The Influence of Electromagnetic Soil Properties on EMI and GPR Sensors in Landmine and UXO Detection

Electromagnetic induction technique (EMI) has been used for landmine detection for a long time. Recently, ground-penetrating radar (GPR) is used more and more often as a stand-alone detector or in combination with EMI sensors. Both techniques are strongly influenced by electromagnetic soil properties, albeit in a different manner. There is a lack of information on electromagnetic soil properties of different soils under various conditions and on how these properties influence different detectors. We present measuring techniques and results of lab and field measurements of physical soil properties and their spatial variability on different scales. A classification system is deduced for magnetic susceptibility and its frequency dependence that can be used to predict the soil influence of tropical soils on EMI sensors and a performance map is designed for the country of Angola. Further, several dual sensors (EMI + GPR) were tested on different soils. The soil influence as predicted by geophysical field investigations and analysis of the electromagnetic soil properties and their spatial variability is in good accordance to the detector performance of the dual sensor test.