1. Liu, Q., J. Shen, J. Yin, H. Liu, and Y. Liu, "Compact 0.92/2.45-GHz dual-band directional circularly polarized microstrip antenna for handheld RFID reader applications," IEEE Transactions on Antennas and Propagation, Vol. 63, 3849-3856, 2015.
doi:10.1109/TAP.2015.2452954
2. Ismail, I. and S. Norzeli, "UHF RFID reader antenna with high gain," International Journal of Electrical and Electronics System Research, Vol. 6, 46-52, 2013.
3. Farswan, A., A. K. Gautam, B. K. Kanaujia, and K. Rambabu, "Design of Koch fractal circularly polarized antenna for handheld UHF RFID reader applications," IEEE Transactions on Antennas and Propagation, Vol. 64, 771-775, 2016.
doi:10.1109/TAP.2015.2505001
4. Chen, Z. N., X. Qing, and H. L. Chung, "A universal UHF RFID reader antenna," IEEE Transactions on Microwave Theory and Techniques, Vol. 57, 1275-1282, 2009.
doi:10.1109/TMTT.2009.2017290
5. Chen, W.-S. and Y.-C. Huang, "A novel CP antenna for UHF RFID handheld reader," IEEE Antennas and Propagation Magazine, Vol. 55, No. 4, 128-137, 2013.
doi:10.1109/MAP.2013.6645148
6. Liu, Q., J. Shen, H. Liu, Y. Wu, M. Su, and Y. Liu, "Low-cost compact circularly polarized directional antenna for universal UHF RFID handheld reader applications," IEEE Antennas and Wireless Propagation Letters, Vol. 14, 1326-1329, 2015.
doi:10.1109/LAWP.2015.2404033
7. Liu, X., Y. Liu, and M. M. Tentzeris, "A novel circularly polarized antenna with coin-shaped patches and a ring-shaped strip for worldwide UHF RFID applications," IEEE Antennas and Wireless Propagation Letters, Vol. 14, 707-710, 2015.
doi:10.1109/LAWP.2014.2378513
8. Wang, Z., et al. "Single-fed broadband circularly polarized stacked patch antenna with horizontally meandered strip for universal UHF RFID applications," IEEE Transactions on Microwave Theory and Techniques, Vol. 59, No. 4, 1066-1073, 2011.
doi:10.1109/TMTT.2011.2114010
9. Cao, R. and S.-C. Yu, "Wideband compact CPW-fed circularly polarized antenna for universal UHF RFID reader," IEEE Transactions on Antennas and Propagation, Vol. 63, 4148-4151, 2015.
doi:10.1109/TAP.2015.2443156
10. Lu, J.-H. and S.-F. Wang, "Planar broadband circularly polarized antenna with square slot for UHF RFID reader," IEEE Transactions on Antennas and Propagation, Vol. 61, 45-53, 2013.
doi:10.1109/TAP.2012.2220103
11. Xu, B., S. Zhang, Y. Liu, J. Hu, and S. He, "Compact broadband circularly polarised slot antenna for universal UHF RFID readers," Electronics Letters, Vol. 51, 808-809, 2015.
doi:10.1049/el.2015.0593