Numerical modeling of crossover and other junction discontinuities in two‐layer microstrip circuits

A mixed‐potential, spatial‐domain integral equation approach is used to model the coupling and junction effects when microstrip structures in two different layers of a common substrate are crossing each other. A Galerkin method, together with the so‐called pseudo‐mesh current distribution for the basis functions, is then applied to accurately characterize multiport junctions. As an example, a four‐port crossover of two microstrip transmission lines is characterized in terms of the S‐parameters.