Broadband right‐angle transition from substrate‐integrated waveguide to rectangular waveguide

A broadband right‐angle transition from a substrate‐integrated waveguide (SIW) to a rectangular waveguide (RWG) is proposed. A coupling aperture etched on the broad wall of the SIW and two stepped ridges embedded in the RWG flange are designed for good matching between both waveguides. A Ka‐band prototype is designed and fabricated. Good agreement between the measured and simulated results is obtained. The measured results show an insertion loss <0.55 dB and a return loss below −15 dB from 31.3 to 38.35 GHz. This broadband transition may be used in microwave and millimetre‐wave circuits and systems.