Applying the multilayer textile conductor technique to improve the wearable passive RF devices

Abstract

The thesis aims to enhance the effectiveness of passive wearable RF device. The purpose of this thesis was to justify the utilization of multilayer of conductor structure to handle the challenge. It was hypothesized that lower reflection and higher gain can be achieved with higher amount of conductor layers. To prove the hypothesis, two two-port devices, the microstrip line and stepped impedance filter, were tested. Based on experience from previous research, EPDM rubber, copper-nickel conductive fabric and cotton fabric were chosen to construct the transmission line. In total, three samples for each device with three different number of conductor layers from one to three were conducted. During the experiment, the reflection coefficient (S11) and S21 of each sample structure, which represents the power transferred from Port 1 to Port 2 or gain, were measured by VNA (vector network analyzer). The parameters described performance of the RF passive devices and were compared in the end of the test. As the results, 3-layer conductor samples of both microstrip line and filter testing revealed the most optimal compared to those of one layer and two-layers.

The experiment procedure was performed at the Wireless Identification and Sensing Systems Research Group (WISE Group) of the Faculty of Medicine and Health Technology.