Analysis and design of universal compact flexible UHF RFID tag antenna

Abstract

The main goal of this paper is to present a design procedure for a flexible compact universal UHF RFID tag antenna suitable for worldwide UHF RFID applications. Systematic design procedure is introduced through the derivation of dipole input impedance general relation using induced EMF method considering wire radius effect. T-matched chart is used to match the tag input impedance with the chip input impedance and finally develop a flow chart to summarize the design procedure. The proposed antenna compactness trend is achieved through applying meandering and Franklin shape to conventional printed dipole antenna. Flexibility trend is achieved through using liquid crystal polymer LCP material as antenna substrate. The proposed antenna covers the frequency band 865MHz to 1078MHz and occupies an area of 1306.6mm2. The computed radar cross section RCS and conjugate match factor CMF insure that the proposed antenna structure is easily detectable and achieves acceptable matching level. Power reflection coefficient PRC is computed, measured and good agreement is obtained. Other antenna parameters such as radiation efficiency, gain and radiation pattern are also calculated. The proposed antenna is cheap, flexible and suitable for UHF RFID universal application.