Novel concentric hexagonal-shaped RFID tag antenna with T-shaped stub matching

This paper presents a unique concentric hexagonal-shaped ring antenna for radio frequency identification (RFID) tags. The rings are excited with a common microstrip feedline. The radiation characteristics of the antenna is improved by locating a horizontal a parasitic element in the vicinity of the hexagonal-shaped rings. The proposed antenna was used in the implementation of a 3×1 antenna array. The impedance match of the 3×1 RFID tag was enhanced by incorporating a T-shaped stub. The antenna is designed to operate at the UHF band from 800 MHz to 960 MHz. It was implemented on FR-4 substrate with dielectric constant and thickness of 4.3 and 1.6 mm, respectively. The size of the RFID tag antenna is 36×10 mm2. Its impedance was matched to Alien Higgs RFIC chip of impedance 10 – j 82.5 Ω at 895 MHz. Measured results show the proposed RFID tag antenna provides an impedance bandwidth, maximum gain and radiation efficiency of 160 MHz, 2 dBi, and 66.5%, respectively. With effective isotropic radiated power (EIRP) limited to 36 dBm to comply with FCC regulations for UHF band RFIDs it radiates in the broadside direction over a range of 9 m making it desirable for various applications including supply chain management, logistic control, and vehicle identification.This project has received funding from Universidad Carlos III de Madrid and the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie Grant 801538. Also, this work is partially supported by RTI2018-095499-B-C31, Funded by Ministerio de Ciencia,Innovación y Universidades, Gobierno de España (MCIU/AEI/FEDER,UE). Additionally, it received funding from the Researchers Supporting Project number (RSP-2021/58), King Saud University, Riyadh, Saudi Arabia