Flexible branch-line coupler using rubber conductive Zoflex for conformal application

• Main Authors: Samingan, M .L., Rahim, S. K. A., Sabran, M. I., Ramli, M. R., Babale, S. A.
• Format: Article
• Published: John Wiley and Sons Inc. 2017
• Subjects: QA75 Electronic computers. Computer science
• Online Access: http://eprints.utm.my/id/eprint/76966/; https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019706510&doi=10.1002%2fmop.30654&partnerID=40&md5=866ac275992ff036f1f1d8e681fcad07

This letter presents the design of a flexible branch-line coupler (BLC) using a rubber conductor (Zoflex) as the conductive element and polydimethylsiloxane (PDMS) as a substrate. The BLC is meant to operate at 6 GHz operating frequency. The use of PDMS material as a substrate for the BLC design adds a special characteristic of the PDMS on this passive microwave device. The PDMS has some unique properties such as transparency, durability, and lightweight. Moreover, its high electrical resistivity of 2.9 × 1014 Ω m and moderate dielectric constant of 2.7 make the PDMS a good substrate material for flexible devices. This desirable property gives the proposed device full range of flexibility and a great advantage in terms of durability without degrading the performance of the BLC. From the results obtained for bending and non-bending conditions, it can be seen that within the frequency range of operation, both the return loss and the isolation are kept below the theoretical value of −10 dB. The slight difference observed in the simulated and measured FBWs is due the fabrication tolerances.