Analytical solutions to eddy-current testing problems for a layered medium with varying properties

A one-parameter family of analytical solutions is found for the case where a single-turn coil is located above a two-layer conducting medium. The conductivity σ and the relative magnetic permeability μ of the upper conducting layer are constants, while for the lower conducting half-space, these are of the form σ(z)=Az^b and μ(z)=Bz^a, where A and B are constants and a+b=-2 or a+b=0. The change in impedance is computed, and the results of numerical simulation are presented