Depth Estimation of a Buried Conductive Sphere as a Model of Unexploded Ordnance Using Electromagnetic Induction Data

In this paper, a novel scheme for depth estimation of a buried conductive sphere as a metallic mine using electromagnetic induction (EMI) data is presented. In electromagnetic induction method, the transmitter coil produces the incident magnetic and electric fields that obey the Maxwell’s equations. In the receiver coil, the received response is created in two modes. Eddy-current mode ( ec V ) is derived from the perfect conductor placed in the shallow depth and another mode called current-channeling response ( cc V ) which depends on the conductivity of the medium. As expected, these responses differ depending on the direction of the incident field related to the receiver coil’s axis. There is a case that the transmitter coil’s axis is parallel to the ground surface and only the eddy current response is measured in the receiver coil. By defining the maximum value of , ecV ,the problem with depth determination transformed into the problem with finding a solution for a nonlinear equation of the form   0 zf .The method is applied to synthetic data with and without random errors. In all of the cases examined, the maximum error in depth is less than 6%.