Three horizontally-polarized (HP) omnidirectional antennas are proposed and discussed in this paper. The antennas are composed of 3, 4 or 5 printed dipoles with corresponding wideband 3-, 4- or 5-way feeding networks. The feeding networks are simple in structure and easy to be matched with the printed dipoles. All of the proposed antennas operate in the frequency band of 1.7-2.7 GHz, covering the DCS1800, WiFi2700 and 4G-LTE bands with reflection coefficients less than -15 dB. Effects of the number of the printed dipoles on omnidirectional characteristics are discussed. Crossed strips are applied to improve their cross-polarization performance. The proposed antennas are simulated, fabricated and measured. Both simulated and measured cross-polarization levels are lower than -15 dB from θ=60° to θ=120° conical cuts. The antennas demonstrate good omnidirectional patterns in the whole frequency band, which can be widely used for indoor 4G-LTE indoor distributed antenna system (DAS) applications.
2. Quan, X. and R. L. Li, "A broadband dual-polarized omnidirectional antenna for base stations," IEEE Transactions on Antennas Propagation, Vol. 61, No. 2, 943-947, Feb. 2013.
3. Huang, H., Y. Liu, and S. Gong, "Broadband omnidirectional dual-polarized antenna with high isolation," Microwave and Optical Technology Letters, Vol. 57, No. 8, 1848-1852, Aug. 2015.
4. Dai, X.-W., Z.-Y. Wang, C.-H. Liang, X. Chen, and L.-T. Wang, "Multiband and dual-polarized omnidirectional antenna for 2G/3G/LTE application," IEEE Antennas and Wireless Propagation Letters, Vol. 12, 1492-1495, 2013.
5. Lin, C. C., L. C. Kuo, and H. R. Chuang, "A horizontally polarized omnidirectional antenna for WLAN applications," IEEE Transactions on Antennas Propagation, Vol. 54, No. 11, 3551-3556, Nov. 2006.
6. Ahn, C. H., S.W. Oh, and K. Chang, "A dual-frequency band omnidirectional antenna polarization diversity of MIMO and wireless communication applications," IEEE Antennas and Wireless Propagation Letters, Vol. 8, 966-970, 2009.
7. Yu, Y., F. Jolani, and Z. Chen, "A wideband omnidirectional horizontally polarized antenna for 4G LTE applications," IEEE Antennas and Wireless Propagation Letters, Vol. 12, 686-689, 2013.
8. Yeo, J. and J.-L. Lee, "Broadband compact series-fed dipole pair antenna with simplified integrated balun," Microwave and Optical Technology Letters, Vol. 56, No. 8, 1731-1734, Aug. 2015.
9. Lu, X.-P. and Y. Li, Novel broadband printed dipole, Vol. 48, No. 10, 1996-1998, Microwave and Optical Technology Letters, Oct. 2006.