A novel branch-line coupler which can operate at two frequencies is presented in this paper. The proposed planar topology, which is different from the conventional one, is analyzed and designed. The new coupler maintains not only compact but also dual-band characteristics. The length of the proposed stepped-impedance lines can be adjusted flexible according to the required operation frequency. In order to verify the method, a dual-band micro-strip coupler operating at 0.9 and 2.1 GHz is fabricated and measured. The simulated and measured results show good agreements.
2. Pozar, D. M., Microwave Engineering, Wiley, New York, 1998.
3. Lin, I.-H., M. DeVincentis, C. Caloz, and T. Itoh, "Arbitrary dual-band components using composite right/left-handed transmission lines," IEEE Trans. Microw. Theory Tech., Vol. 52, No. 4, 1142-1149, Apr. 2004.
4. Park, M.-J. and B. Lee, "Dual-band, cross coupled branch line coupler," IEEE Microw. Wireless Compon. Lett., Vol. 15, No. 10, 655-657, Oct. 2005.
5. Hsu, C.-L. and J.-T. Kuo, "Design of dual-band branch line couplers with circuit miniaturization," Asia Pacific Microwave Conference, 16-20, Dec. 2008.
6. Zheng, S. Y. and S. H. Yeung, "Dual-band rectangular patch hybrid coupler," EEE Trans. Microw. Theory Tech., Vol. 56, No. 7, 1721-1728, Jul. 2004.
7. Chin, K.-S. and K.-M. Lin, "Compact dual-band branch-line and rat-race couplers with stepped-impedance-stub lines," IEEE Trans. Microw. Theory Tech., Vol. 58, No. 5, 1213-1221, May 2010.
8. Zheng, N., L. Zhou, and W.-Y. Yin, "A novel dual-band π-shaped branch-line coupler with stepped-impedance stubs," Progress In Electromagnetics Research Letters, Vol. 25, 11-20, 2011.
9. Kim, H. and B. Lee, "Dual-band branch-line coupler with port extensions," IEEE Trans. Microw. Theory Tech., Vol. 58, No. 3, 651-655, Mar. 2010.
10. Yeung, L. K., "A compact dual-band 90 coupler with coupled-line sections," IEEE Trans. Microw. Theory Tech., Vol. 59, No. 9, 2227-2232, Sept. 2011.
11. Atlasbaf, Z. and K. Forooraghi, "A new dual band branch-line coupler using coupled lines," Antennas, Propagation & EM Theory, 1-4, Oct. 2006.
12. Wong, F. L. and K. K. M. Cheng, "A novel planar branch line coupler design for dual-band applications," IEEE Trans. Microw. Theory Tech., Vol. 2, 903-906, Jun. 2004.
13. Monti, G. and L. Tarricone, "Dual-band artificial transmission lines branch-line coupler," International Journal of RF and Microwave Computer-Aided Engineering, 2007.
14. Keshavarz, R., M. Danaeian, M. Movahhedi, and A. Hakimi, "A compact dual-band branch-line coupler based on the interdigital transmission line," 2011 19th Iranian Conference on Electrical Engineering (ICEE), 1-5, May 2011.
15. Jizat, N. M., S. K. A. Rahim, T. A. Rahman, and M. R. Kamarudin, "Miniaturize size of dual band branch-line coupler by implementing reduced series arm of coupler with stub loaded," Microwave and Optical Technology Letters, Vol. 53, No. 4, Apr. 2011.
16. Cheng, K. K. M. and F. L. Wong, "A novel approach to the design and implementation of dual-band compact planar 90 branch line coupler," IEEE Trans. Microw. Theory Tech., Vol. 52, No. 11, 2458-2462, Nov. 2004.
17. Hong, J.-S. and M. J. Lancaster, Microstrip Filters for RF/Microwave Applications, 2001.