Mode-matching design of substrate-integrated waveguide couplers

A mode-matching based full-wave analysis method is deployed to design H-plane substrate integrated waveguide (SIW) couplers. In order to apply simple and straightforward mode-matching techniques, commonly used circular vias are replaced by proper square ones. K-band and W-band SIW directional couplers are designed with square vias, and then analyzed and validated by commercially available full-wave field solvers using circular vias. Comparisons with measurements on a Ka-band SIW coupler with circular vias verify the analysis and design procedure.