A Novel Broadband Microstrip to Waveguide Transition at W band with High Manufacturing Tolerance Suitable for MMIC Packaging

This paper presents a novel broadband microstrip to waveguide transition using substrate integrated waveguide (SIW) at W band suitable for MMIC packaging. The microstrip line is first transformed to SIW and then SIW is transformed to air filled reduced height rectangular waveguide with height being equal to the substrate thickness. The reduced height waveguide is brought to full height through a λ/4 chebyshev stepped impedance transformer. Design is robust and suitable for manufacturing with little variation in performance due to assembly. One back to back transition is developed. Experimental result shows that return loss of better than 10 dB is achieved over a bandwidth of 26 % with insertion loss of 0.52 dB at centre frequency for single transition.