Polymer Membranes to Quarter-Wave Match Gaussian Optics

We demonstrate two simple quarter-wave matches designed in the WR10 band that reduce peak reflected power by 20 and 25 dB near the match frequencies by use of membrane layers on high-density polyethylene (HDPE)–air interfaces. Polytetrafluoroethylene (PTFE)-based membranes that are expanded by regular air voids are layered upon a solid HDPE slab by use of spray adhesive. S-parameter measurements with and without these layers demonstrate the improved power match with two to three membrane layers applied.