Multi-Level Proximity Coupled Transitions for Microwave and Millimeter Wave Applications

The success of microwave and millimeter wave integrated circuits and monolithic arrays will largely depend on the development of highly accurate CAD methods. This article presents precise methodologies to model a variety of proximity coupled transitions which may be instrumental in the design of MIC and MMIC components. Two specific structures are investigated, which are a two-level microstrip-microstrip transition and a slot-coupled microstrip-microstrip transition. The analysis is based on solving coupled integral equations by method of moments. In the formulation, the Green´s function for the grounded dielectric substrate is used, which takes into account all the radiation, surface wave and material effects. Meanwhile, mutual coupling due to dominant as well as higher order modes is automatically included in the method of moments solution. Numerical results are illustrated for the energy distribution as a function of offset, stub length or slot dimensions.