A low-profile wideband circularly polarized aperture stacked patch (ASP) antenna without air dielectric layers is presented. The new circular ASP antenna, which is fed by two orthogonal dual-offset lines through an asymmetric crossed slot, delivers a wide bandwidth of 80% for the 10-dB return loss and similar input impedance characteristics for the two ports. Then, a novel broadband 90° hybrid feed network is employed to achieve good impedance matching, balanced power splitting and consistent 90° (±9°) phase shifting across the wide operating band. The two unbalanced feed lines are connected to the respective ports of the feed network comprising a three-section Wilkinson power divider and a broadband 90° phase shifter. It is found that the proposed antenna can achieve a measured impedance bandwidth of 91.3% (2.44-6.54 GHz), a measured 3-dB axial ratio (AR) bandwidth of 86.4% (2.5-6.3 GHz), and a measured gain bandwidth of 60.9% from 3.2 to 6.0 GHz for the gain >4 dBic. In addition, a comparison between the proposed wideband CP antenna and related wideband CP and ASP antennas in the literature is made.
2. Su, C. W. and J. S. Row, "Slot-coupled microstrip antenna for broadband circular polarization," Electron. Lett., Vol. 42, No. 6, 318-319, Mar. 2006.
3. Guo, Y. X., L. Bian, and X. Q. Shi, "Broadband circularly polarized annular-ring microstrip antenna," IEEE Trans. Antennas Propag., Vol. 57, No. 3, 2471-2477, Aug. 2009.
4. Nasimuddin, Z. N. Chen and X. M. Qing, "A compact circularly polarized cross-shaped slotted microstrip antenna," IEEE Trans. Antennas Propag., Vol. 60, No. 3, 1584-1588, Mar. 2012.
5. Nasimuddin, K. P. Esselle and A. K. Verma, "Wideband circularly polarized stacked microstrip antennas," IEEE Antennas Wireless Propag. Lett., Vol. 6, 21-24, 2007.
6. Wu, T. Q., H. Su, L. Y. Gan, H. Z. Chen, J. Y. Huang, and H. W. Zhang, "A compact and broadband microstrip stacked patch antenna with circular polarization for 2.45-GHz mobile RFID reader," IEEE Antennas Wireless Propag. Lett., Vol. 12, 623-626, 2013.
7. Shekhawat, S., P. Sekra, D. Bhatnagar, V. K. Saxena, and J. S. Saini, "Stacked arrangement of rectangular microstrip patches for circularly polarized broadband performance," IEEE Antennas Wireless Propag. Lett., Vol. 9, 910-913, 2010.
8. Nakamura, T. and T. Fukusako, "Broadband design of circularly polarized microstrip patch antenna using artificial ground structure with rectangular unit cells," IEEE Trans. Antennas Propag., Vol. 59, No. 6, 2103-2110, Jun. 2011.
9. Bian, L., Y. X. Guo, L. C. Ong, and X. Q. Shi, "Wideband circularly polarized patch antenna," IEEE Trans. Antennas Propag., Vol. 54, No. 9, 2682-2686, Sep. 2006.
10. Guo, Y. X., K. W. Khoo, and L. C. Ong, "Wideband circularly polarized patch antenna," IEEE Trans. Antennas Propag., Vol. 56, No. 2, 319-326, Feb. 2008.
11. Lin, C., F. S. Zhang, Y. C. Jiao, F. Zhang, and X. Xue, "A three-fed microstrip antenna for wideband circular polarization," IEEE Antennas Wireless Propag. Lett., Vol. 9, 359-362, 2010.
12. Ghorbani, K. and R. B. Waterhouse, "Dual polarized wide-band aperture stacked patch antennas," IEEE Trans. Antennas Propag., Vol. 52, No. 8, 2171-2174, Aug. 2004.
13. Serra, A. A., P. Nepa, G. Manara, G. Tribellini, and S. Cioci, "A wide-band dual polarized stacked patch antenna," IEEE Antennas Wireless Propag. Lett., Vol. 6, 141-143, 2007.
14. Zheng, S. Y., W. S. Chan, and K. F. Man, "Broadband phase shifter using loaded transmission line," IEEE Microw. Wireless Comp. Lett., Vol. 20, No. 9, 498-500, Sep. 2010.