Simplified design of multilayered substrate-integrated waveguide riblet-saad couplers

A simplified design procedure for dual- and triple-layered Riblet-Saad directional couplers in substrate-integrated waveguide (SIW) technology is presented. Emphasis is placed on a design that considers ease of fabrication and includes interface ports such as microstrip-to-SIW transitions with straight, bent, and mitered microstrip lines. Designs are performed in an HFSS environment, which is verified by comparison with an independent field-solver simulation.