On the use of fitting models for the time-domain analysis of problems with frequency-dependent parameters

The use of fitting models in the time-domain analysis of electromagnetic problems is of great interest. The aim of this paper is to describe the main features of different fitting models, and the key issues related to their use and practical implementation in computational codes. Equivalent circuit representations of such models are also presented, and numerical applications are shown in order to provide guidelines for the choice of the method that is the most suitable to solve a specific problem.