Conductivity measurements of the earth at ELF

This paper describes a simple method for determining the effective conductivity of a relatively flat conducting earth at ELF. The method is based on the quasi-static approximations to the Hertz vector potential for both the vertical and horizontal magnetic dipole. From these approximations, expressions for the magnetic field are obtained. By taking the ratio of the vertical component to the horizontal component, a simple relation is obtained for conductivity which is independent of the magnetic dipole moment. The relation is also independent of the source and receiver height provided they are located near the boundary.