Design of a broadband CP antenna for RFID readers

RFID 리더용 광대역 원편파 안테나 설계

  • Received : 2015.04.21
  • Accepted : 2015.05.29
  • Published : 2015.08.31


In this paper, we considered a design method of a circular polarization (CP) antenna for UHF (ultra high frequency) RFID (Radio Frequency IDentification) readers. The antenna is a dual-fed circular microstrip patch which produces right-handed CP. Quadrature hybrid coupler is used for dual feeding. The outputs of the coupler and circular patch are connected through copper wires, and the inductive reactance produced by the connecting wires is compensated by a ring-shaped slot inserted inside the circular patch. The effects of the geometrical parameters of the proposed antenna on the antenna performance are examined, and the parameters are adjusted to be suitable for the operation in North American UHF RFID band (902-928 MHz), which includes domestic UHF RFID band. The antenna is fabricated, and the experiment results reveal a frequency band of 854-993 MHz for a voltage standing wave ratio < 2. The fabricated antenna is connected to a commercial RFID reader, and it showed a good performance of tag identification.


CP antenna;RFID antenna;microstrip antenna;dual-feeding;broadband antenna


  1. H.-W. Son, H. Park, and H.-G. Jeon, "Design of a circularly polarised radio-frequency identification reader antenna with high return loss," IET Microwaves, Antennas & Propagation, vol. 5, no. 15, pp. 1844-1848, 2011.
  2. Nasimuddin, Z. N. Chen, and X. Qing, "Asymmetric-circular shaped slotted microstrip antennas for circular polarization and RFID applications," IEEE Trans. on Antennas and Propagation, vol. 58, no. 12, pp. 3821-3828, Dec. 2010.
  3. C.-Y.-D. Sim and C.-J. Chi, "A slot loaded circularly polarized patch antenna for UHF RFID reader," IEEE Trans. on Antennas and Propagation, vol. 60, no. 10, pp. 4516—4521, Dec. 2014.
  4. C.-Y.-D. Sim, Y.-W. Hsu, and G. Yang, "Slits loaded circularly polarized universal UHF RFID reader antenna," IEEE Antennas and Wireless Propagation Letters, vol. 14, pp. 827-830, 2015.
  5. Q. Liu, J. Shen, H. Liu, and Y. Liu, "Dual-band circularly-polarized unidirectional patch antenna for RFID reader applications," IEEE Trans. on Antennas and Propagation, vol. 62, no. 12, pp. 6428-6434, Dec. 2014.
  6. K. Finkenzeller, RFID handbook, Chichester: UK: Wiley, 2003.
  7. R. Garg, P. Bhartia, A. Bahl, and A. Ittipiboon, Microstrip antenna design handbook, Artech House, 2001.
  8. G. Kumar and K. P. Ray, Broadband microstrip antennas, Artech House, 2003.
  9. K.-L. Wong, Compact and broadband microstrip antennas, New York; John Wiley & Sons, 2002.