This paper presents a compact tri-band dual-polarized planar monopole antenna, which is linearly polarized in the lower and middle bands and circularly polarized in the higher band. The antenna is printed on a substrate with an asymmetrical ground plane and a loaded vertical stub. The vertical stub and asymmetrical ground plane are mainly used to make the antenna obtain circular polarization performance in the higher band. The antenna has been built and tested. Its measured 10-dB impedance bandwidths are 2.39-2.54 GHz, 3.38-4.12 GHz, and 4.57-6.04 GHz, which can fully cover all the 2.4/5.2/5.8 GHz WLAN bands, all the 2.4/5.5 GHz Wi-Fi bands, and 3.5/5.5 GHz WiMAX bands. In the higher band, the measured 3-dB axial-ratio bandwidth is 5.4-5.83 GHz.
2. Song, Y., Y.-C. Jiao, G. Zhao, and F.-S. Zhang, "Multiband CPW-fed triangle-shaped monopole antenna for wireless applications," Progress In Electromagnetics Research, Vol. 70, 329-336, 2007.
3. Chen, H., X. Yang, Y. Z. Yin, S. T. Fan, and J. J. Wu, "Triband planar monopole antenna with compact radiator for WLAN/WiMAX applications," IEEE Antenn. Wirel. Propag. Lett., Vol. 12, 1440-1443, 2013.
4. Sze, J.-Y., T.-H. Hu, and T.-J. Chen, "Compact dual-band annular-ring slot antenna with meandered grounded strip," Progress In Electromagnetics Research, Vol. 95, 299-308, 2009.
5. Majid, H. A., M. K. Adb Rahim, M. R. Hamid, and M. F. Ismail, "Frequency reconfigurable microstrip patch-slot antenna with directional radiation pattern," Progress In Electromagnetics Research, Vol. 144, 319-328, 2014.
6. Row, J. S. and K. W. Lin, "Low-profile design of dual-frequency and dual-polarised triangular microstrip antennas," Electronics Letters, Vol. 40, No. 3, 156-157, 2004.
7. Falade, O. P., Y. Gao, and X. Chen, "Stacked-patch dual-polarized antenna for triple band handheld terminals," IEEE Antenn. Wirel. Propag. Lett., Vol. 12, 202-205, 2013.
8. Mathew, S. and R. Anitha, "A compact tri-band dual-polarized corner-truncated sectoral patch antenna," IEEE Trans. Antennas Propagat., Vol. 63, No. 12, 5842-5845, 2015.
9. Wang, Y. and X. Li, "Compact triple-band dual-polarized microstrip patch antenna for wireless applications," Microwave Opt. Technol. Lett., Vol. 56, No. 4, 778-783, 2014.