Investigation of EMI response for magnetically susceptible and conductive rough surfaces

Electromagnetic induction (EMI) sensing has been identified as most promising technology for the detection and discrimination of subsurface metallic objects, particularly unexploded ordnances (UXO). In EMI, the sensors are detecting signals that are produced by induced and permanent magnetic polarizations. Soils, which contain small magnetic particles, called magnetically susceptible soils, can produce EMI responses and, therefore, mask or modify the object´s EMI response. These soils are a major source of false positives when searching for UXO using magnetic or EMI sensors. Studies show that in adverse areas up to 30% of identified electromagnetic (EM) anomalies are attributed to geology. Therefore, to enhance UXO detection as well as discrimination in geological environments, the effects of the magnetic soils on the magnetic and EMI signal need to be studied in details. In this paper, the method of auxiliary sources (MAS) is applied to investigate the EMI response from magnetically susceptible rough surfaces.