Electromagnetic field solution for a coil of arbitrary shape moving relative to a set of ferromagnetic layers

A general method is described for solving the electromagnetic field problem associated with a coil of arbitrary shape moving above a number of planar ferromagnetic layers. It is shown that power and the 3-axis forces may be determined using a Fourier transform technique, together with a transmission line analogue. If only power and the 3-axis forces are required, and not the actual field components, then the use of the inverse Fourier transforms can be obviated by utilising the Parseval identity. The method is illustrated with a simple example.