Design of Electro-Textile UHF RFID Tag through T-Match Network

Abstract

This paper presents the development of electro-textile tag antenna based on two omni-directional antennas for UHF RFID application. The design of the tag antenna adopts T-match-based RFID tag concept to develop a compact and high bandwidth antenna at UHF range between 860 MHz to 960 MHz. In the wearable RFID tag antenna, copper core electro-textile fabric is acting as the radiating element and polyester fabric with a dielectric constant of 2.1 used as the substrate (non-conductive layer). The performance of the antennas is compared in terms of its reflection coefficient, impedance matching and design complexity. Among the challenges in designing a UHF RFID tag antenna is the complexity in integrating IC chip into the tag. During operation, signal from RFID reader will activate the IC chip and the backscattered signal containing information will be sent to the reader. Therefore, to allow optimum operation, the impedance value of the antenna must match with the IC’s impedance to ensure maximum power transfer between the antenna and the IC chip. The first antenna design consists of T-match with meander method to produce various tunable antenna features while the second design only features a T-match based RFID design with less antenna geometric structure. The second antenna design is observed to have better reflection coefficient and impedance matching compared to the first antenna design. The data from this simulation is useful to determine fabrication complexity in designing UHF RFID tag antenna tag based on electro-textile material.