Broadband SIW-to-Waveguide Transition in Multilayer LCP Substrates at W-Band

In this letter, we present a substrate-integrated waveguide (SIW) to air-filled rectangular waveguide (WG) transition in multilayer liquid crystal polymer substrates at W-band. The proposed transition is achieved by using a SIW-fed linearly flared antipodal slot line inserted into a WG. To minimize packaging leakage, no guided vias are utilized in the slot line region. Full-wave simulation reveals a low insertion loss of 0.8 dB for the proposed transition at W-band. To experimentally demonstrate this design, a WG-to-SIW-to-WG transition was fabricated and characterized. The measured insertion and reflection loss of the back-to-back transition is less than 1.8 and -11 dB, respectively, at W-band.