This paper presents a broadband and compact planar quasi-Yagi antenna for multi-band 3G/4G applications.The proposed quasi-Yagi antenna consists of a modified bow-tie driver to increase the bandwidth, a passive reflector and two passive directors to enhance the directivity at the lower and higher ends of the operating band, respectively. A microstrip-to-slotline transition feed is used to achieve a good impedance matching. It is confirmed by experiment that general approaches for increasing the bandwidth of bow-tie antennas are also feasible for quasi-Yagi antennas with bow-tie drivers. Furthermore, with the modified bow-tie structure, the directivity of the antenna at higher frequencies of the operating band is enhanced, because the bow-tie shape can form planar horn structures and has strong current distributions at high frequencies. The proposed antenna is fabricated using an FR4 substrate with a dielectric constant of 4.2, and the overall dimension of the antenna is 1.24λgc×0.94λgc. Measurements show that the 10 dB return loss bandwidth is 80.4%, operating from 1.45 to 3.4 GHz. Measured gains are greater than 4 dBi within the entire bandwidth, and the front-to-back ratios are greater than 10 dB. Having a multi-band coverage within the 3G/4G spectra,this antenna is expected to be used for 3G/4G mobile wireless communications.
2. Sor, J., W. R. Deal, Y. Qian, and T. Itoh, "A broadband quasi-Yagi antenna array," European Microwave Conference, 255-258, 1999.
3. Zhang, X. Y., S. Lin, G. L. Huang, R. Q. Jiang, and R. N. Cai, "Research on broadband and high-gain quasi-Yagi antenna and array," IEEE International Conference on Control, Automation and Systems Engineering (CASE), 1-4, 2011.
4. Zhang, X. C., J. G. Liang, and J. W. Xie, "The quasi-Yagi-antenna subarray fed by an orthogonal T junction," Progress In Electromagnetics Research Letters, Vol. 4, 109-112, 2008.
5. Kaneda, N., W. R. Deal, Y. X. Qian, R. Waterhouse, and T. Itoh, "A broadband planar quasi-Yagi antenna," IEEE Transactions on Antennas and Propagation, Vol. 50, No. 8, 1158-1160, Aug. 2002.
6. Chen, S. Y. and P. Hsu, "Broadband microstrip-fed modified quasi-Yagi antenna," IEEE/ACES International Conference on Wireless Communications and Applied Computational Electromagnetics, 208-211, 2005.
7. Zhao, Y., Z. X. Shen, and W. Wu, "Wideband and low-profile monocone quasi-Yagi antenna for end-fire radiation," IEEE Antennas and Wireless Propagation Letters, Vol. 99, Jun. 2016.
8. Jiang, K., Q. G. Guo, and K. M. Huang, "Design of a wideband quasi-Yagi microstrip antenna with bowtie active elements," IEEE International Conference on Microwave and Millimeter Wave Technology (ICMMT), 1122-1124, 2010.
9. Zhang, S., Z. Tang, and Y. Yin, "Wideband planar printed quasi-Yagi antenna with band-notched characteristic," Progress In Electromagnetics Research Letters, Vol. 48, 137-143, 2014.
10. Wang, H., Y. Chen, F. S. Liu, and X. W. Shi, "Wideband and compact quasi-Yagi antenna with bowtie-shaped drivers," Electronics Letters, Vol. 49, No. 20, 1262-1264, Sep. 2013.
11. Bourqui, J., M. Okoniewski, and E. C. Fear, "Balanced antipodal Vivaldi antenna with dielectric director for near-field microwave imaging," IEEE Transactions on Antennas and Propagation, Vol. 58, No. 7, 2318-2326, Jul. 2010.
12. Peng, F., J. C. Jiao, W. Hu, and F. S. Zhang, "A miniaturized antipodal Vivaldi antenna with improved radiation characteristics," IEEE Antennas and Wireless Propagation Letters, Vol. 10, 127-130, 2011.
13. Wang, Y. P., X. G. Liu, H. P. Guo, and X. M. Yang, "Design of the directional horn-shaped planar antenna used for wireless mouse online test," IEEE MTT-S International Microwave Workshop Series on RF and Wireless Technologies for Biomedical and Healthcare Applications, 1-3, 2013.
14. Pan, B., Y. Li, and G. E. Ponchak, "A 60-GHz CPW-fed high-gain and broadband integrated horn antenna," IEEE Transactions on Antennas and Propagation, Vol. 57, No. 4, 1050-1056, Apr. 2009.
15. Ta, S. X., B. C. Kim, H. S. Choo, and I. Park, "Wideband quasi-Yagi antenna fed by microstrip-toslotline transition," Microwave and Optical Technology Letters, Vol. 54, No. 1, 150-153, Jan. 2012.
16. Wang, H., S.-F. Liu, W.-T. Li, and X.-W. Shi, "Design of a wideband planar microstrip-fed quasi- Yagi antenna," Progress In Electromagnetics Research Letters, Vol. 46, 19-24, 2014.