Full-wave analysis of three-dimensional microstrip discontinuities by a new spectral domain approach

The paper presents a new extension of the spectral domain method, which is applicable not only to planar circuits but also to arbitrarily shaped three-dimensional metallization structures embedded in layered media. For the first time, 3D piecewise continuous surface currents are used to model junctions between planar and vertical parts of the investigated structure. It is shown that a careful treatment of the integrals in the spectral domain leads to convergent and stable expressions for the coupling matrix elements despite the discontinuity of the basis functions.