Coplanar Waveguide Transmission Line Made with Knitted Fabric Technology

This paper presents a knitted coplanar waveguide (CPW) transmission line for wearable wireless systems operating in the 5G NR n71 band. The line is intended to candidate RF interconnect for future integration into wearable systems covering the n71 downlink band of 617–652 MHz and uplink band of 663–698 MHz. Unlike printed, sewn, embroidered, multilayer, or coaxial textile transmission lines, the proposed CPW structure is formed directly during a single knitting process using only one machine. The line was designed for 50 Ω impedance and experimentally characterized with the use of S-parameter measurements. The results show impedance matching better than |S11| < −15 dB within the investigated frequency range and transmission coefficient |S21| > −2 dB at 600 MHz. These results confirm the feasibility of using knitwear as a functional RF transmission medium for fully textile-integrated sub-GHz 5G wearable communication systems.