Multilayer Universal Transitions Between Substrate Integrated Waveguides and Rectangular Waveguides

Even though a large number of transitions between metal waveguides and planar transmission lines/waveguides has been proposed thus far, due to different shortcomings, none of them has gained widespread acceptance comparable to the ubiquitous right-angle coaxial-to-waveguide adaptor. In this paper, we show a transition between substrate integrated waveguide (SIW) and rectangular waveguide (RWG) with many desired properties for broad practical application, starting with cost-effective and adjustable implementation from the initial design to the end product, over compact size and ease of making waveguide joints, to wideband operation. Transition performance is examined with respect to a range of substrate thickness, permittivity and layer count choices. Two pairs of adaptor prototypes in back-to-back configurations have been fabricated and tested for concept validation. One is at K band, on a PTFE-based substrate with RWG interface between the transitions, while the other is at U band, on a ceramic-based substrate with SIW interface between the transitions.