Silica-based post-wall waveguide with high-performance input and output transitions for E-band passive front-end

We proposed silica-based post-wall waveguides (PWWs) with input and output (I/O) transitions from microstrip line for 71-76 GHz and 81-86 GHz, respectively. The PWWs were designed so that their reflection keeps lower than ™20 dB at the aimed frequencies. They were fabricated in silica substrates and the performance was measured. Realization of the bandwidth of 23.6% was confirmed at the lower band. The transmission loss of the sole PWW was 0.0326 dB/mm and the insertion loss of the transition was 0.25 dB, both at 85 GHz. The silica-based PWWs can offer a practical platform for passive front-end including antenna feeds in E-band.