This paper presents a novel tunable microstrip patch antenna using liquid crystal. It adopts a differentially-driven, aperture-coupled, and stacked-patch structure. Compared with the conventional design, this novel antenna achieves a larger frequency tuning range, much wider impedance bandwidth, higher radiation efficiency and gain. Besides, the novel antenna facilitates the bias design as the bias signal is naturally isolated from the RF signal. Both the conventional and novel antennas are designed to operate at 28 GHz using an RT/Duroid 5880 substrate and K15 liquid crystal. Results show that the novel antenna has a tuning range of 3.1%, an impedance bandwidth of 6.43%, a peak radiation efficiency of 70%, and a peak realized gain of 6.5 dBi, while the conventional antenna has the tuning range of 2.7%, impedance bandwidth of 3.57%, peak radiation efficiency of 45%, and peak realized peak gain of 4.5 dBi.
1. Erdil, E., K. Topalli, and M. Unlu, "Frequency tunable microstrip patch antenna using RF MEMS technology," IEEE Trans. Antennas and Propagation, Vol. 55, No. 4, 1193-1196, April 2007. doi:10.1109/TAP.2007.893426
2. Caekenberghe, K. V. and K. Sarabandi, "A 2-bit Ka-band RF MEMS frequency tunable slot antenna," IEEE Antennas and Wireless Propagation Letters, Vol. 7, 179-182, March 2008. doi:10.1109/LAWP.2008.921390
3. Qin, P. Y., F. Wei, and Y. J. Guo, "A wideband-to-narrowband tunable antenna using a reconfigurable filter," IEEE Trans. Antennas and Propagation, Vol. 63, No. 5, 2282-2285, May 2015. doi:10.1109/TAP.2015.2402295
4. Boukarkar, A., X. Q. Lin, and Y. Jiang, "A dual-band frequency-tunable magnetic dipole antenna for WiMAX/WLAN applications," IEEE Antennas and Wireless Propagation Letters, Vol. 15, 492-495, July 2015.
5. Sazegar, M., Y. L. Zheng, H. Maune, C. Damm, X. H. Zhou, J. Binder, and R. Jakoby, "Low-cost phased-array antenna using compact tunable phase shifters based on ferroelectric ceramics," IEEE Trans. Microwave Theory and Techniques, Vol. 59, No. 5, 1265-1273, May 2011. doi:10.1109/TMTT.2010.2103092
6. Lovat, G., P. Burghignoli, and S. Celozzi, "A tunable ferroelectric antenna for fixed-frequency scanning applications," IEEE Antennas and Wireless Propagation Letters, Vol. 5, No. 1, 353-356, December 2006. doi:10.1109/LAWP.2006.880694
7. Missaoui, S., A. Gharbi, and M. Kaddour, "Design and simulation reconfigurable liquid crystal patch antennas on foam substrate," Journal of Chemical Engineering & Materials Science, Vol. 2, No. 7, 96-102, 2011.
8. Palomino, G. P., M. Barba, J. A. Encinar, R. Cahill, R. Dickie, P. Baine, and M. Bain, "Design and demonstration of an electronically scanned reflectarray antenna at 100 GHz using multiresonant cells based on liquid crystals," IEEE Trans. Antennas and Propagation, Vol. 63, No. 8, 3722-3727, August 2015. doi:10.1109/TAP.2015.2434421
9. Papanicolaou, N. C., M. A. Christou, and A. C. Polycarpou, "Frequency-agile microstrip patch antenna on a biased liquid crystal substrate," Electron. Lett., Vol. 51, No. 3, 202-204, February 2015. doi:10.1049/el.2014.3856
10. Polycarpou, A. C. and M. A. Christou, "Tunable patch antenna printed on a biased nematic liquid crystal cell," IEEE Trans. Antennas and Propagation, Vol. 62, No. 10, 4980-4987, July 2014. doi:10.1109/TAP.2014.2344099
11. Liu, L. and R. J. Langley, "Liquid crystal tunable microstrip patch antenna," Electron. Lett., Vol. 44, No. 20, 1179-1180, September 2008. doi:10.1049/el:20081995
12. Missaoui, S., S. Missaoui, and M. Kaddour, "Reconfigurable microstrip patch antenna based on liquid crystals for microwave applications," Proceedings of Engineering & Technology, 23-28, 2016.
13. Deo, P., D. M. Syahkal, L. Seddon, S. E. Day, and F. A. Fernandez, "Microstrip device for broadband (15–65 GHz) measurement of dielectric properties of nematic liquid crystals," IEEE Trans. Microwave Theory and Techniques, Vol. 63, No. 4, 1388-1398, April 2015. doi:10.1109/TMTT.2015.2407328
14. Gao, S. C., L. W. Li, M. S. Leong, and T. S. Yeo, "A broad-band dual-polarized microstrip patch antenna with aperture coupling," IEEE Trans. Antennas and Propagation, Vol. 51, No. 4, 898-900, April 2003. doi:10.1109/TAP.2003.811080
15. Zhang, Y. P., "Design and experiment on differentially-driven microstrip antennas," IEEE Trans. Antennas and Propagation, Vol. 55, No. 10, 2701-2708, October 2007. doi:10.1109/TAP.2007.905832
16. Rathi, V., G. Kumar, and K. P. Ray, "Improved coupling for aperture coupled microstrip antennas," IEEE Trans. Antennas and Propagation, Vol. 44, No. 8, 1196-1198, August 1996. doi:10.1109/8.511831
17. Choudhary, N., A. Tiwari, J. S. Saini, V. K. Saxena, and D. Bhatnagar, "Planar arrangement of modified concentric rings with defected ground for mobile and wireless communication systems," Progress In Electromagnetics Research B, Vol. 47, 161-169, 2016. doi:10.2528/PIERM16012401
18. Islam, M. T., M. N. Shakib, and N. Misran, "Broadband E-H shaped microstrip patch antenna for wireless systems," Progress In Electromagnetics Research, Vol. 98, 163-173, 2009. doi:10.2528/PIER09082302
19. Eldek, A. A., A. Z. Elsherbeni, and C. E. Smith, "Dual-wideband square slot antenna with a U-Shaped printed tuning stub for personal wireless communication systems," Progress In Electromagnetics Research, Vol. 53, 319-333, 2005. doi:10.2528/PIER04103001
20. De Gennes, P. G. and J. Prost, The Physics of Liquid Crystals, 2nd Ed., Clarendon Press, 1995.