Fabrication of 180 GHz PTFE-filled waveguide and its bandpass filters by SR direct etching

Micro RF parts and components have recently been developed by various microfabrication technologies. This paper treats a trial fabrication of the PTFE-filled waveguide for short millimeter-wave with the use of the SR (synchrotron radiation) etching process of PTFE. First, PTFE-filled waveguides of different lengths for 180 GHz operation are fabricated, and the propagation losses are evaluated using the measurement results. Next, iris-coupled bandpass filters (BPF) with 3- and 5-stage Chebyshev responses are designed and fabricated. The frequency characteristics of the PTFE-filled waveguide BPFs are measured, and the validity of the fabrication process is confirmed.