A W-band quadrature hybrid coupled substrate integrated waveguide diplexer

A W-band quadrature hybrid coupled substrate integrated waveguide (SIW) diplexer is proposed in this paper. Instead of conventional 0.127 mm substrate for W-band circuitry, a 0.254 mm substrate is chosen for Q-value improvement. A WR-10 waveguide to 0.254 mm SIW transition is developed for measurement purpose. The diplexer comprises four Riblet short slot quadrature hybrids and two pairs of 3-pole SIW channel filters. The two passbands of the diplexer are 84 GHz 6% BW and 93 GHz 6% BW respectively. The measured results matched well with simulated ones.