Design of a compact size tag antenna based on split ring resonator for UHF RFID application

Abstract

In this article, a new design of miniaturized split-ring resonator antenna using a meander line technique with a simple impedance matching method applicable to UHF-RFID tags is presented. The new approach is based on the integration of a meander line into the radiating element of SRR to reduce the electrical tag size and a theoretical demonstration to calculate the conjugate impedance matching and directly attach the antenna with the chip. The new SRR antenna, which is printed on the flexible substrate Arlon CuClad 250LX, is designed using Alien Higgs 3 RFID ASIC whose input impedance is 25-j190. The prototype antenna has a low-cost compact size (18.28 mm × 18.28 mm) with a read range higher than 4 m within the RFID UHF band and with a roughly 4.2-m peak range at 915 MHz. As a proof of behavior, a tag prototype is fabricated and measured to operate at a UHF RFID band. Based on some works' results, an optimized design is obtained with a 48% size reduction compared with the classic split ring resonator antenna and with a good impedance matching the antenna with RFID ASIC without the need for any external matching network. K E Y W O R D S compact antenna, passive tag antenna, split ring resonator, UHF RFID application 1 | INTRODUCTIONNowadays, radio frequency identification (RFID) is becoming an increasingly interesting technology for research due to its high data rate, easy read/write functions and long readable range between the reader and tag. This development in RFID technology has led to great demands in different fields all over the world, such as smart parking application agriculture, airport access control, libraries, vehicle security military, passport, supply chain, and mobile payment. 1,2 In the applications of RFID systems, the only active component reader sends radio frequency signals and information to a passive tag which includes an antenna and an integrated circuit (ASIC). The chip which contains the information about the tagged item converts the unmodulated signal and sends its information back to the reader for the automatic identification of objects. 3,4 In several UHF RFID applications, we need a small-tag antenna to be flexibly mounted on different device components. For this reason, the major challenging aspect concerning passive UHF RFID tags is the size reduction. In literature, there are lots of studies which have been reported on small tags based on dipole or patch antennas. In Ref. 5, the authors presented an overview of the RFID passive tag in terms of antenna impedance, chip impedance, antenna performance, and read range measurement. Moreover, a study on the performance of RFID U-shaped dipole tag antenna that is placed on different permittivity surfaces has been reported in Ref. 6. For near-field applications, 7 a meander line tag antenna designed for Europe band and used for short-distance RFID UHF tagging for tracking packages in transport is proposed. In Ref. 8, an RFID tag dipole antenna operating at the whole UHF frequency band has been presented to be used for bandwidth optimizati...

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