Modeling and design of stepped transitions for substrate-integrated waveguides
A stepped transition in substrate-integrated waveguide (SIW) technology is presented. The transition changes the height of an SIW using multiple steps. The steps can be tuned by varying the length of shorted stubs which represents a generalization of a stepped-impedance transformer. An accurate equivalent circuit model of the steps is developed, that enables fast optimization. An exemplary transition is designed that features two frequency bands at 20 GHz and 30 GHz. For verification the model is compared to full-wave simulation and a back-To-back coplanar-waveguide (CPW) to full-height SIW transition is fabricated and measured.