Effective spectral domain analysis of planar circuits with different kinds of expansion functions on rectangular subdomains

This paper deals with the computation of planar circuits embedded in layered media by a spectral domain approach using a very flexible nonuniform mesh strategy in connection with different kinds of expansion functions. Besides the widely used rooftop or piecewise sinusoidal current expansion functions allowing piecewise constant distributions normal to the current direction, we use expansion functions allowing linear cross distributions. The focal point of this contribution is to present a spectral domain approach which can support a large class of expansion functions. Computational efficiency is achieved, on the one hand, by analytical and numerical integration schemes to improve the convergence and accuracy of the spectral domain integrals, and on the other hand, by a matrix fill technique which is based on the efficient detection of identities in the coupling matrix to avoid redundant computations. Typical applications are shown in order to demonstrate some of the advantages of the presented approach.