Design and Implementation of Electro-Textile Ground Planes for Wearable UHF RFID Patch Tag Antennas

Localization, wireless monitoring, and emerging body-centric wireless systems demand low-cost and low-power devices that are efficient, maintenance-free, and comfortable to wear. Patch-type UHF radio frequency identification (RFID) tag antennas realized using electro-textiles are promising candidates for this purpose. In this letter, we design a patch-type tag antenna operating at 900 MHz and investigate how different types of ground planes using electro-textiles affect the antenna performance. Various conductive fabrics and embroidery structures are considered. We demonstrate that depending on the ground plane structure and density, it is possible to influence the tag impedance behavior and radiation characteristics. Furthermore, wireless reflectometry measurements are conducted to characterize the sheet resistance for the investigated electro-textiles. We then use the sheet resistance in modeling the conductive fabric ground planes in a full-wave electromagnetic solver. Our results contribute to deeper understanding of the complex electro-textiles structures and guidelines for future practical wearable antenna designs.