The sub-surface magnetic fields produced by a line current source on a non-flat earth

Summary A simple cylindrical model is employed to estimate the effect of non-flatness of the ground on the sub-surface electromagnetic field from a current-carrying cable on the surface. It is shown that, if the surface curvature is sufficiently small, the fields in the cylinder model are very similar to those for the conducting half-space model of the earth employed earlier. The results can be used to provide estimates of expected errors in electromagnetic direction-finding of a buried receiving terminal.The research reported here was supported in part by the Mine Safety Center, U.S. Bureau of Mines.