Trial fabrication of PTFE-based E-plane waveguide coupler for short millimeter-wave by SR etching

It has been reported that the SR (synchrotron radiation) etching process is useful to construct PTFE-based microstructures. This paper treats a trial fabrication of the PTFE-based E-plane waveguide coupler for short millimeter-wave based on the SR etching process of PTFE, with the aim of developing integrated waveguide circuits. First, a cavity-type 3-dB directional coupler is designed at 180 GHz. In this paper, an integrated PTFE pattern, in which the two 3-dB couplers and the matching section are cascaded, is fabricated. Then, the frequency characteristics of the PTFE-based E-plane waveguide coupler are measured, and the validity of the fabrication process is verified.