Novel compact dual-band branch-line couplers are presented. By using ahalf elliptical-ring impedance stub as a basic unit, dual-band branch-line couplers are obtained. Sincea couple of half elliptical-ring impedance stubs can be folded inward to its enclosed areawithout overlap, the branch-line couplercan be miniaturized. In order to verify the effectiveness of the half elliptical-ring impedance stub, two different branch-line couplers operating at 2.4/5.8 GHz are designed, fabricated and tested. Measured results agree well with simulated ones. Compared with the stepped-impedance-stub branch-line couplers, sizes of the proposed couplers are reduced by 43% and 30%, respectively.
"Novel Compact Dual-Band Branch-Line Couplers with Half Elliptical-Ring Impedance Stub Lines," Progress In Electromagnetics Research Letters,
Vol. 56, 9-15, 2015. doi:10.2528/PIERL15072802
1. Cheng, K.-K.M. and F.-L.Wong, "A novel approach to the design and implementation of dual-band compact planar 90º branch-line coupler," IEEE Transactions on Microwave Theory and Techniques, Vol. 52, No. 11, 2458-2463, Nov. 2004. doi:10.1109/TMTT.2004.837151
2. Park, M.-J. and B. Lee, "Dual-band, cross coupled branch line coupler," IEEE Microwave Wireless Components Letters, Vol. 15, No. 10, 655-657, Oct. 2005. doi:10.1109/LMWC.2005.856683
3. Collado, C., A. Grau, and F. De Flaviis, "Dual-band planar quadrature hybrid with enhanced bandwidth response," IEEE Transactions on Microwave Theory and Techniques, Vol. 54, No. 1, 180-188, Jan. 2006. doi:10.1109/TMTT.2005.860306
4. Zhang, H. L. and H. L., "A stub tapped branch-line coupler for dual-band operations," IEEE Microwave Wireless Components Letters, Vol. 17, No. 2, 106-108, Feb. 2007. doi:10.1109/LMWC.2006.890330
5. Tanaka, H., Y. Sasaki, T. Hashimoto, Y. Yagi, and Y. Ishikawa, "Miniaturized 90 degree hybrid coupler using high dielectric substrate for QPSK modulator," IEEE MTT-S International Microwave Symposium Digest, Vol. 2, 793-796, Jun. 1996.
6. Toyoda, I., T. Hirota, T. Hiraoka, and T. Tokumitsu, "Multilayer MMIC branch-line coupler and broad-side coupler," IEEE Microwave and Millimeter-Wave Monolithic Circuits Symposium Digest, 79-82, Jun. 1992.
7. Eccleston, K. W. and S. H. M. Ong, "Compact planar microstripline branch-line and rat-race couplers," IEEE Transactions on Microwave Theory and Techniques, Vol. 51, No. 10, 2119-2115, Oct. 2003. doi:10.1109/TMTT.2003.817442
8. Sheta, A. F., A. S. Mohra, and S. F. Mahmoud, "A new class of miniature quadrature couplers for MIC and MMIC applications," Microwave and Optical Technology Letters, Vol. 34, No. 3, 215-219, Aug. 2002. doi:10.1002/mop.10421
9. Tseng, C. H. and C. L. Chang, "A rigorous design methodology for compact planar branch-line and rat-race couplers with asymmetrical T-structures," IEEE Transactions on Microwave Theory and Techniques, Vol. 60, No. 7, 2085-2092, Jul. 2012. doi:10.1109/TMTT.2012.2195019
10. Ahn, H. R. and S. Nam, "Compact microstrip 3-dB coupled-line ring and branch-line hybrids with new symmetric equivalent circuits," IEEE Transactions on Microwave Theory and Techniques, Vol. 61, No. 3, 1067-1078, Feb. 2013. doi:10.1109/TMTT.2013.2241783
11. Chin, K. S., K. M. Lin, Y. H, and Wei, "Compact dual-band branch-line and rat-race couplers with stepped-impedance-stub lines," IEEE Transactions on Microwave Theory and Techniques, Vol. 58, No. 5, 1213-1221, May 2010. doi:10.1109/TMTT.2010.2046064