Abstract
A semi-empirical model is used to predict the change in coil impedance ΔZ due to currents induced in a conducting plate by an axisymmetric ferrite-cored coil. The model uses experimental (rather than theoretical) values of the Hankel transform of the magnetic field produced by the source coil as an input to the calculations of ΔZ and avoids lengthy finite-element or boundary-element compulations. The validity of the model was tested using experimental measurements of ΔZ for both an air-cored and ferrite-cored coil. The calculated and measured values of ΔZ agree to within 15%or better.