Vertical and Horizontal Transitions of Substrate Integrated Waveguides Within a Multi-Layered PCB for High Speed Signaling Applications

In this paper, transitions between substrate integrated waveguides (SIW) within a multi-layered printed circuit board (PCB) are studied. Particularly, horizontal (within the same layer) and vertical (between different layers) transitions are investigated. Horizontal transitions are studied by implementing SIW arcs with various radii having their side wall ground vias located on a curve. Vertical transitions are implemented between SIWs in different layers by placing a narrow rectangular opening in the PCB ground plane between the waveguides. The size of this opening is varied to provide an effective layer-to-layer transition between the SIWs. Insertion losses and field distributions of both types of transitions are examined. Both are shown to have relatively low-loss, with approximately 3.8 dB/inch loss for the straight and curved SIW structures at 100GHz and only an additional 0.2 dB of loss over a straight SIW's when a vertical transition is incorporated.