Design and Fabrication of PTFE-Filled Waveguide Components by SR Direct Etching

Mitsuyoshi KISHIHARA
Tadashi KAWAI

IEICE TRANSACTIONS on Electronics   Vol.E95-C    No.1    pp.122-129
Publication Date: 2012/01/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E95.C.122
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Microwaves, Millimeter-Waves
X-ray lithography,  bandpass filters,  directional couplers,  sputtering,  dielectric materials,  

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The metallic waveguide is one of many effective media for millimeter- and submillimeter-waves because of the advantage of its low-loss nature. This paper describes the fabrication method of PTFE-filled waveguide components with the use of the SR (synchrotron radiation) direct etching process of PTFE, sputter deposition of metal, and electroplating. PTFE is known as a difficult material to process with high precision. However, it has been reported that PTFE microstructures can be fabricated by the direct exposure to SR. First, an iris-coupled waveguide BPF with 5-stage Chebyshev response is designed and fabricated for the Q-band. It is demonstrated that the present process is applicable for the fabrication of the practical components inclusive of narrow patterns. Then, a cruciform 3 dB coupler with air-filled posts is designed and fabricated for the Q-band. Directivity and matched state of the coupler can be realized by “holes” in the dielectric material. The measurement results are also shown.