A multiple-arm dipoles antenna array based on magnetic coupling is proposed for ultra-high frequency (UHF) radio frequency identification (RFID) near-field applications. The design utilizes four multiple-arm dipoles to form a square region fed by a quarter-wave impedance transformer double-side parallel stripline (QDSPSL) structure. Broadband performance can be obtained for two different resonant frequencies caused by different dipole arm lengths. Moreover, in induction area, stronger and more uniform magnetic field distribution is generated for phases of currents on three dipole arms being kept in the same compared to conventional single-arm dipole. A 170 × 170 × 1.6 mm3 antenna has been fabricated on an FR-4 substrate to fit RFID near-field application. The measured 10-dB impedance bandwidth is 190 MHz (810-1000 MHz), which covers the entire UHF RFID frequency band (860-960 MHz). Measured tests on the antenna read range are carried out, exhibiting a reading region of 100 × 100 mm2 and 100% reading rate within 200 mm for near-field tags.
2. Ahmad, M. Y. and A. S. Mohan, "Novel bridge-loop reader for positioning with HF RFID under sparse tag grid," IEEE Transactions on Industrial Electronics, Vol. 61, No. 1, 555-566, 2013.
3. Ding, X. M., K. Zhang, H. Yu, and L. Zhu, "A novel magnetic coupling UHF near field RFID reader antenna based on multilayer-printed-dipoles array," IEEE Transactions on Magnetics, Vol. 50, No. 1, 1-4, 2014.
4. Shi, J., X. Qing, and Z. N. Chen, "Electrically large zero-phase-shift line grid-array UHF nearfield RFID reader antenna," IEEE Transactions on Antennas and Propagation, Vol. 62, No. 4, 2201-2208, 2014.
5. Li, X. and Z. Yang, "Dual-printed-dipoles reader antenna for UHF near-field RFID applications," IEEE Antennas and Wireless Propagation Letters, Vol. 10, No. 1, 239-242, 2011.
6. Zheng, J., C. Zhou, Y. Yang, X. He, and C. Y. Mao, "QDSPSL-fed straight dipoles antenna array for UHF RFID near-field applications," Progress In Electromagnetics Research Letters, Vol. 72, 107-112, 2018.
7. Wei, X. D., H. L. Zhang, and B. J. Hu, "Novel broadband center-fed UHF near-field RFID reader antenna," IEEE Antennas and Wireless Propagation Letters, Vol. 14, 703-706, 2015.
8. Zheng, J., Y. Yang, X. He, and C. Y. Mao, "A CP Antenna of wide half-power beamwidth for UHF RFID near- and far-field applications," Progress In Electromagnetics Research Letters, Vol. 72, 61-67, 2018.
9. Cho, C., J. Ryoo, I. Park, and H. Choo, "Design of a novel ultra-high frequency radio-frequency identification reader antenna for near-field communications using oppositely directed current," IET Microwaves Antennas and Propagation, Vol. 4, No. 10, 1543-1548, 2010.
10. Cho, C., C. Lee, J. Ryoo, and H. Choo, "Planar near-field RFID reader antenna for item-level tagging," IEEE Antennas and Wireless Propagation Letters, Vol. 10, No. 11, 1100-1103, 2011.
11. Pakkathillam, J. K. and M. Kanagasabai, "A novel UHF near-field RFID reader antenna deploying CSRR elements," IEEE Transactions on Antennas and Propagation, Vol. 65, No. 4, 2047-2050, 2017.
12. Daiki, M. and E. Perret, "Near-field modular antenna concept with configurable reading area for RFID applications," IEEE Transactions on Antennas and Propagation, Vol. 65, No. 3, 1015-1025, March 2017.