In this paper, a CPW-fed reconfigurable clover-shaped antenna with switchable circular polarization is proposed. This antenna consists of a clover-shaped patch, four p-i-n diodes, and two pairs of quarter-circular-rings. By electrically controlling the four p-i-n diodes to form two orthogonal bow-tie shaped current paths, the proposed antenna can be operated in two modes: the left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP) modes. Two pairs of quarter rings are used to improve the bandwidth and AR performance of the antenna. The measured 10-dB reflection coefficient and 3-dB axial-ratio (AR) bandwidth of the prototype antenna is approximately 12.3% and 19%, respectively, which is enough for some wireless applications such as WLAN IEEE 802.11 b/g (4%). Gain and radiation pattern are also presented.
2. Yang, X. X., B. C. Shao, F. Yang, A. Elsherbeni, and B. Gong, "A polarization reconfigurable patch antenna with loop slots on the ground plane," IEEE Antennas Wireless Propag. Lett., Vol. 11, 69-72, Mar. 2012.
doi:10.1109/LAWP.2011.2182595
3. Ho, K. M. J. and G. M. Rebeiz, "Microstrip antennas with full polarization diversity using packaged RF MEMS switches,", Chicago, USA, Jul. 8-14, 2012.
4. Aghdam, S. A., "Reconfigurable antenna with a diversity filtering band feature utilizing active devices for communication systems," IEEE Trans. Antennas Propag., Vol. 61, No. 10, 5223-5228, Oct. 2013.
doi:10.1109/TAP.2013.2273812
5. Yang, Z. X., H. C. Yang, J.-S. Hong, and Y. Li, "Bandwidth enhancement of a polarization-reconfigurable patch antenna with stair-slots on the ground," IEEE Antennas Wireless Propag. Lett., Vol. 13, 579-582, Apr. 2014.
doi:10.1109/LAWP.2014.2312971
6. Khidre, A., K. L. Lee, F. Yang, and A. Z. Elsherbeni, "Circular polarization reconfigurable wideband E-shaped patch antenna for wireless applications," IEEE Trans. Antennas Propag., Vol. 61, No. 2, 960-964, Feb. 2013.
doi:10.1109/TAP.2012.2223436
7. Rajagopalan, H., J. M. Kovitz, and Y. R. Samii, "MEMS reconfigurable optimized E-shaped patch antenna design for cognitive radio," IEEE Trans. Antennas Propag., Vol. 62, No. 3, 1056-1064, Feb. 2014.
doi:10.1109/TAP.2013.2292531
8. Row, J. S., W. L. Liu, and T. R. Chen, "Circular polarization and polarization reconfigurable designs for annular slot antennas," IEEE Trans. Antennas Propag., Vol. 60, No. 12, 5998-6002, Dec. 2012.
doi:10.1109/TAP.2012.2211556
9. Tsai, J. F. and J. S. Row, "Reconfigurable square-ring microstrip antenna," IEEE Trans. Antennas Propag., Vol. 61, No. 5, 2857-2860, May 2012.
doi:10.1109/TAP.2013.2244554
10. Seo, D. and Y. Sung, "Reconfigurable square ring antenna for switchable circular polarization," Electronics Letters, Vol. 51, No. 6, 428-440, Mar. 2015.
doi:10.1049/el.2014.4362
11. Lee, S. W. and Y. J. Sung, "Reconfigurable Rhombus-shaped patch antenna with Y-shaped feed for polarization diversity," IEEE Antennas Wireless Propag. Lett., Vol. 14, No. 3, 163-166, Feb. 2015.
doi:10.1109/LAWP.2014.2358651
12. Lee, S. W. and Y. J. Sung, "Simple polarization reconfigurable antenna with T-shaped feed," IEEE Antennas Wireless Propag. Lett., Vol. PP, No. 99, 1-4, Mar. 2015.
13. Li, Y., Z. Zhang, W. Chen, and Z. Feng, "Polarization reconfigurable slot antenna with a novel compact CPW-to-slot line transition for WLAN application," IEEE Antennas Wireless Propag. Lett., Vol. 9, 252-255, 2010.
doi:10.1109/LAWP.2010.2046006
14. Zarei, V., M. Azarmanesh, H. Boudaghi, and S.-A. Aghdam, "A novel CPW-fed polarization reconfigurable microstrip antenna," IEEE Microwave Measurement Conference (ARFTG), 1-4, Tampa, USA, Jun. 6, 2014.
15. Valizade, A., M. Ojaroudi, and N. Ojaroudi, "CPW-fed small slot antenna with reconfigurable circular polarization and impdeance bandwidth characteristcis for DCS/WiMAX applications," Progress In Electromagnetics Research C, Vol. 56, 65-72, 2015.
doi:10.2528/PIERC14122901
16. Sze, J.-Y. and S.-P. Pan, "Design of broadband circularly polarized square slot antenna with compact size," Progress In Electromagnetics Research, Vol. 120, 513-533, 2011.
doi:10.2528/PIER11070106