Full-wave analysis of multiport microstrip circuits by efficient evaluation of multilayered Green´s functions in spatial domain

In this paper, a full wave analysis of multiport microstrip circuits is presented, which is based on the efficient computation of spatial domain dyadic Green´s functions and accurate modeling of method of moments (MoM) with perfectly matched ports. With fast and accurate extracting all the surface wave and adequate leaky wave modes, the spatial domain dyadic Green´s functions of layered structures can be evaluated by combining the discrete complex image method (DCIM) and the all modes method in near and non-near region, respectively. The Delta-Gap model is adopted to model the exciting port, while the others are perfectly matched by pre-determining the current exponentially decaying. The matrix pencil method (MPM) are adopted to extract the scattering parameters of a 4-port microstrip branch-line hybrid. Very good agreement between simulation and measurement results have been found from the provided example.