Broadband T-matching loop tag antenna design for on-body UHF RFID applications

• Published in: Microwave and optical technology letters Vol. 56; no. 5; pp. 1194 - 1200
• Main Authors: Chiu, Chien-Wen, Tsai, Min-Chuan, Wang, Hwang-Cheng, Wu, Ter-Feng
• Format: Journal Article
• Language: English
• Published: New York Blackwell Publishing Ltd 01.05.2014; Wiley Subscription Services, Inc
• Subjects: Antennas; Cards; Computer simulation; equivalent circuit model; Human; Microwaves; on-body proximity effect; Polyvinyl chlorides; Radio frequency identification; reading range; T-matching transformer; Transformers; UHF RFID tag antenna design
• ISSN: 0895-2477; 1098-2760
• DOI: 10.1002/mop.28291

ABSTRACT This article proposes a printed loop tag antenna placed near a human body for use on student radio frequency identification cards. The proposed tag antenna printed on a polyvinylchloride card is a one‐wavelength loop fed by a T‐matching transformer. An equivalent lumped‐circuit for the T‐matching transformer is presented to synthesize the T‐matching feeding structure. A four‐layer stratified elliptical cylinder with physical parameters is utilized as a human model for EM simulations. The simulated bandwidth of the T‐matching loop tag antenna is 91 MHz (866–957 MHz, 10%). The T‐matching structure allows the loop antenna to have wideband characteristics. Experiments revealed that the reading distance ranges from about 3.3 to −6 m when the tag was placed in different positions on the human chest in the open space environment. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1194–1200, 2014