Analytical Solution for the Change in Impedance of a Coil Situated above a Moving Conducting Medium

Analytical solution of eddy current testing problem is obtained for the case of a moving two-layer medium. The electrical conductivity and magnetic permeability of the upper layer are exponential functions of the vertical coordinate. The solution is found by the method of a double Fourier transform. The change in impedance is expressed in closed form as a double integral. Solution can be generalized for the case of a multilayer medium with arbitrary number of layers