Multi-port network modeling of multilayer planar circuits containing ground plane slots

A new approach for Multi-Port Network Modeling (MNM) of multilayer planar circuits containing slots is introduced. Generalized network formulation for aperture problems is combined with Okoshi's model for planar circuits to obtain a unified circuit model for two planar circuits coupled through a slot of arbitrary shape in their common ground plane. The methodology, which can be easily generalized to structures having more than two layers, is clarified by applying the method to a multilayer microstrip filter.