A broadband waveguide to substrate integrated coaxial line (SICL) transition for w-band applications

In this paper, a vertical transition from the air-filled rectangular waveguide to the substrate integrated coaxial line (SICL) is proposed for wideband operation in millimeter-wave band. A stepped SICL and a rectangle patch probe are introduced to improve impedance matching of the proposed transition. Analysis of dimension parameters is developed to investigate the robustness and manufacturability of the transition. A back-to-back transition prototype operating at W-band (75–110GHz) is realized by multi-layer PCB process. The measured results agree well with the simulation results, which exhibit a frequency bandwidth of 20% for S11 less than −14 dB and an insertion loss of 1.7dB at 91.8GHz.