This paper presents a design procedure for the generation of circular polarization (CP) from the composite right/left handed (CRLH) transmission line-(TL) with a coupled inter-digit structure and an inductive stub. The Ex and Ey components are generated from the parallel stubs and the fingers, respectively. The 90°-phase difference can be obtained by optimizing the dimension of the unit cell. In addition, the suitable amplitude ratio of |Ex| and |Ey| for CP generation is obtained by selecting a suitable position of the CRLH-TL between both edges of the ground. As a result, a CP with a measured bandwidth of 30.5% for an axial ratio (AR) of < 3 dB in the boresight direction is obtained. Using the behavior in both the left-handed (LH) and right-handed (RH) frequency regions, a scanning angle of the main beam of approximately 30° can be obtained by varying the frequency between 2.58 GHz and 2.99 GHz. Furthremore, the principle of CP generation is discussed.
"Design of Leaky Wave Antenna with Composite Right-/Left-Handed Transmission Line Structure for Circular Polarization Radiation," Progress In Electromagnetics Research C,
Vol. 33, 109-121, 2012. doi:10.2528/PIERC12082106
1. Caloz, C. and T. Itoh, Electromagnetic Metamaterials, Willey-Interscience, 2006, Nov. 2010.
2. Hashemi, M. R. and T. Itoh, "Dual-mode leaky-wave excitation in symmetric composite right/left-handed structure with center vias," IEEE MTT-S International Microwave Symposium Digest, 9-12, Anaheim, USA, May 2010.
3. Liu, L., C. Caloz, and T. Itoh, "Dominant mode (DM) leaky-wave antenna with backfire-to-endfire scanning capability," Electronics Letters, Vol. 38, No. 23, 1414-1416, Nov. 2002. doi:10.1049/el:20020977
4. Caloz, C. and T. Itoh, "Novel microwave devices and structures based on the transmission line approach of meta-materials," IEEE MTT-S International Microwave Symposium Digest, Vol. 1, 195-198, 2003.
5. Cheng, J., A. Alphones, and M. Tsutsumi, "Double periodic composite right/left handed transmission line and its applications to leaky wave antennas," IEEE Transactions on Antennas and Propagation, Vol. 59, 3679-3686, Oct. 2011.
6. Cheng, J., A. Alphones, and L. C. Ong, "Broadband leaky wave antenna based on composite right/left handed substrate integrated waveguide," Electronics Letters, Vol. 46, No. 24, 1584-1585, Nov. 2010.
7. Kang, M., C. Caloz, and T. Itoh, "Miniaturized MIM CRLH transmission line structure and application to backfire-to-endfire leaky-wave antenna," IEEE Antennas and Propagation Society International Symposium, Vol. 1, 827-830, 2010.
8. Losito, O., M. Gallo, V. Dimiccoli, D. Barletta, and M. Bozzetti, "A tapered design of a CRLH-TL leaky wave antenna," Proceedings of the 5th European Conference on Antennas and Propagation, (EUCAP), 357-360, 2011.
9. Dong, Y. and T. Itoh, "Composite right/left-handed substrate integrated waveguide and half mode substrate integrated waveguide leaky-wave structure," IEEE Transactions on Antennas and Propagation, Vol. 59, 767-775, 2011. doi:10.1109/TAP.2010.2103025
10. Hashemi, M. R. and T. Itoh, "Circularly polarized composite right/left-handed leaky wave antenna," IEEE International Conference Wireless Information Technology and System, (ICWITS), 1-4, 2010. doi:10.1109/ICWITS.2010.5612258
11. Cheng, J. and A. Alphones, "Leaky-wave radiation behavior from a double periodic composite right/left-handed substrate integrated waveguide," IEEE Transactions on Antennas and Propagation, Vol. 60, 1727-1735, 2012. doi:10.1109/TAP.2012.2186248
12. Anghel, A. and R. Cacoveanu, "Improved composite right/left-handed cell for leaky-wave antenna," Progress In Electromagnetics Research Letters, Vol. 22, 59-69, 2011.
13. Ishii, M. and T. Fukusako, "Circularly polarized leaky wave antenna using composite right/left-handed transmission line," PIERS Proceedings, 972-975, Moscow, Russia, Aug. 19-23, 2012.
14. Joseph, R., S. Nakao, and T. Fukusako, "Broadband square slot antenna for polarization with separated l-probes and stubs in the slot," IEICE Trans. Communication, Vol. E94-B, No. 04, 951-959, Apr. 2011. doi:10.1587/transcom.E94.B.951