Transient equivalent surface field excitations via rational approximation by vector fitting

Individual components of large and complex system simulations can be represented in a black-box manner by equivalent magnetic and electric surface fields on an enclosing surface. To accurately analyze the wideband behavior of such components by transient simulations, a transformation of these equivalent surface fields to the time domain is required. A novel approach to imprint frequency domain equivalent surface fields as a transient near field source in the Finite Integration Technique (FIT) is presented. Based on a rational approximation, a fast, accurate, and by construction causal state space system is constructed to describe the wideband transient near field sources.