University of Oulu

S. Wu, J. Yuan, J. Chen and Y. Li, "Compact Circularly Polarized Microstrip Ring Antenna Using Capacitive Coupling Structure for RFID Readers," in IEEE Access, vol. 8, pp. 32617-32623, 2020, doi: 10.1109/ACCESS.2020.2973719

Compact circularly polarized microstrip ring antenna using capacitive coupling structure for RFID readers

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Author: Wu, Shiji1; Yuan, Jiade1; Chen, Jiangcheng2;
Organizations: 1College of Physics and Information Engineering, Fuzhou University, Fuzhou 350108, China
2Center for Wireless Communications-Radio Technologies Research Unit (CWC-RT), University of Oulu, 90570 Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.8 MB)
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Language: English
Published: Institute of Electrical and Electronics Engineers, 2020
Publish Date: 2020-05-06


This paper presents a compact circularly polarized microstrip antenna for radio frequency identification (RFID) readers. The dimensions of the proposed antenna are reduced by etching a cross slot in the radiation patch and loading four grounded coupling patches on the four corners of the radiation patch. An inverted Z-shaped coupling feedline is used to realize circularly polarized operation. The measured -10 dB |S11| bandwidth, 3-dB axial ratio bandwidth and maximum gain are 872–1095 MHz, 888–933 MHz, and 5.52 dBi, respectively, at 922 MHz frequency. The overall dimension of the proposed antenna is 0.36 λ g X 0.36 λ g X 0.05 λ gg is the guide wavelength at the center frequency of 915 MHz). The proposed antenna has small size with good overall performance and is suitable for compact RFID devices.

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Series: IEEE access
ISSN: 2169-3536
ISSN-E: 2169-3536
ISSN-L: 2169-3536
Volume: 8
Pages: 32617 - 32623
Article number: 8998232
DOI: 10.1109/ACCESS.2020.2973719
Type of Publication: A1 Journal article – refereed
Field of Science: 213 Electronic, automation and communications engineering, electronics
Funding: This work was supported in part by the Cooperation Project of Industry University Research of Fujian Province, China, under Grant 2019H6007, and in part by the Science and Technology Project Plan of Fuzhou, China, under Grant 2018-G-89.
Copyright information: © The Authors 2020. This work is licensed under a Creative Commons Attribution 4.0 License. For more information, see