Broadband Waveguide-to-Microstrip Transition Design Using Patch Structure in the D-Band(140 GH -160 GHz)

This paper presents the design of a waveguide-to-microstrip transition for millimeter-wave integrated circuits that fulfills the requirements of the D-band (140 GHz-160 GHz). The proposed transition is vertically structured to minimize loss, transferring signals that propagate from a WR-7 standard waveguide to a microstrip via a substrate integrated waveguide (SIW). To enable efficient mode conversion, a patch is inserted between the standard waveguide and SIW. Using HFSS from Ansoft, the frequency characteristics were analyzed by adjusting the patch size and position of the pin, achieving a wideband design. The substrate used for the design is Taconic RF-35, with a dielectric constant of 3.5 (loss tangent 0.0018) and a thickness of 0.254 mm. Simulation results demonstrate a bandwidth from 124 GHz to 163 GHz, with an average insertion loss of -0.9 dB or less and an average return loss of -10 dB or less across the band.