On the wideband EMI response of a rotationally symmetric permeable and conducting target

A simple and accurate model is presented for computation of the electromagnetic induction (EMI) resonant frequencies of canonical conducting and ferrous targets, in particular, finite-length cylinders and rings. The imaginary resonant frequencies correspond to the well known exponential decay constants of interest for time-domain EMI interaction with conducting and ferrous targets. The results of the simple model are compared to data computed numerically, via method-of-moments (MoM) and finite-element models. Moreover, the simple model is used to fit measured wideband EMI data from ferrous cylindrical targets (in terms of a small number of parameters). It is also demonstrated that the general model for the magnetic-dipole magnetization, in terms of a frequency-dependent diagonal dyadic, is applicable to general rotationally symmetric targets (not just cylinders and rings).