Implementation of Hexagonal Open-Loop Resonators Utilizing the FSC Technique for Chipless RFID Tag Solutions

This paper presents a novel design for a compact planar multiresonator customised for chipless RFID tag applications, with a focus on optimising encoding efficiency. The tag features three hexagonal slots, meticulously incorporated into the underside of a 50Ω microstrip transmission line. The operational frequency range extends from 2.12 GHz to 5.45 GHz, yielding a total bandwidth of 3.33 GHz. Detection information is encoded in the spectral domain through Frequency Shift Coding, enabling the generation of a maximum as 343 unique codes utilising three resonators. This tag is distinctive for its capability to generate distinct resonant frequencies through alterations in the slot dimensions. The design and simulation were conducted on an RT5880 substrate, which has a dielectric constant of 2.2 and a remarkably low loss tangent of 0.0009.