Soil influence on sensor based landmine detection

Today more than 75 countries are affected by landmines and/or unexploded ordnance (UXO). Since landmines are one of the cheapest weapons they are widely used and remain as a deadly hazard to civilians even many years after the end of armed conflicts. The recent number of officially registered casualties is nearly 6000 per year whereas the number of unknown victims is high. One of the reasons for the broad spread of landmines is the low cost of production which is partially only between 3 – 5 USD. However, the costs for clearing of a single landmine are between 300 and 500 USD.  

Electromagnetic technique is widely used for the detection of landmines that are buried in soils. Among numerous search methods the metal detector remains the most common tool in landmine detection which is due to its low price and easy usability. UXO are usually easy to detect because of their high metal contents. In contrast, anti personnel mines are often difficult to find because of their low metal content which holds true in particular for modern mines.

The “soil problem” when using metal detectors occurs frequently in the following way: The instrument works on the basis of electromagnetic induction and detects metallic objects in the ground. However, modern anti personnel mines contain only little metal so that the operator of the metal detector is forced to work with the instrument in the most sensitive mode. The sensitive setup of the instrument evokes in turn a high false alarm rate which is caused either by small metal particles in the soil or by certain soil properties. Especially tropical soils often impede the performance of metal detectors used for landmine detection. False alarm rates of up to 1000 : 1 are not rare. The aim of our investigations is in particular to characterise and classify the crucial magnetic soil properties and to determine their influence on the performance of metal detectors.