volume | PIER Journals

Abstract

A topology, equations and design methodology for complex impedance-transforming branch-line hybrid couplers are presented. This method also allows the realization of real impedance-transforming to higher impedances. Limitations for real, imaginary and complex impedances are discussed. Test results are shown for a 3 dB 50 to 450 Ω hybrid coupler, at a 2 GHz center frequency, with a 21% bandwidth, an amplitude balance of 4.35±1 dB and a phase balance of 92.16°±8.8°. To showcase the complex impedance scenario, two 3 dB 50 Ω to 70-200j Ω are measured at a 2 GHz center frequency. One of these couplers uses a technique for reducing the chip size, yielding a 22.5% bandwith, 4-0.9 dB amplitude balance and 93.22°-6.74° phase balance, while acomplishing a 25% size reduction.

1. Wang, Q., J. Lim, and Y. Jeong, "Design of a compact dual-band branch line coupler using composite right/left-handed transmission lines," Electronics Letters, Vol. 52, No. 8, 630-631, April 2016.
doi:10.1049/el.2015.3923

2. Kim, H., H. Wi, S. Wang, J. Kim, and W. Jung, "Broadband 3 dB microstrip hybrid coupler with low dielectric substrate for X-Band applications," 2016 IEEE 17th Annual Wireless and Microwave Technology Conference (WAMICON), 1-3, Clearwater, FL, 2016.

3. Morimoto, Y., A. Waghmare, K. Dhwaj, and T. Itho, "A compact branch line coupler using novel periodically grounded slow-wave structure," 2016 IEEE MTT-S International Microwave Symposium (IMS), 1-3, San Francisco, CA, 2016.

4. Hettak, K. and K. Elgaid, "3D Ultra miniature MMIC TFMS 90◦ coupler fabricated with a standard air bridge process," 2011 41st European Microwave Conference (EuMC), 846-849, Manchester, 2011.

5. Nosrati, M., "An extremely miniaturized microstrip branch-line coupler," MicroWave and Optical Technology Letters, Vol. 51, No. 6, 1403-1406, June 2009.
doi:10.1002/mop.24365

6. Cheng, S., E. Ojefors, P. Hallbjorner, and A. Rydberg, "Compact reflective microstrip phase shifter for traveling wave antenna applications," IEEE Microwave and Wireless Components Letters, Vol. 16, No. 7, 431-433, July 2016.
doi:10.1109/LMWC.2006.877126

7. Wong, Y. S., S. Y. Zheng, and W. S. Chan, "Multifolded bandwidth branch line coupler with filtering characteristic using coupled port feeding," Progress In Electromagnetics Research, Vol. 118, 17-35, 2011.
doi:10.2528/PIER11041401

8. Cheng, Y. J., L. Wang, J. Wu, and Y. Fan, "Directional coupler with good restraint outside the passband and its frequency-agile application," Progress In Electromagnetics Research, Vol. 135, 759-771, 2013.
doi:10.2528/PIER12121009

9. Gai, C., Y. C. Jiao, and Y. L. Zhao, "Compact dual-band branch-line coupler with dual transmission lines," IEEE Microwave and Wireless Components Letters, Vol. 26, No. 5, 325-327, May 2016.
doi:10.1109/LMWC.2016.2549099

10. Gupta, R., S. Anderson, and W. Getsingert, "Impedance-transforming 3-dB 90◦ hybrids," IEEE Transactions on Microwave Theory and Techniques, Vol. 35, No. 12, 1303-1307, December 1987.
doi:10.1109/TMTT.1987.1133852

11. Lin, C.-S., S.-F. Chang, C.-C. Chang, and Y.-H. Shu, "Design of a reflection-type phase shifter with wide relative phase shift and constant insertion loss," IEEE Transactions on Microwave Theory and Techniques, Vol. 55, No. 9, 1862-1868, September 2007.
doi:10.1109/TMTT.2007.903346

12. Jing, X. and S. Sun, "Design of impedance transforming 90 degree patch hybrid couplers," 2014 Asia-Pacific Microwave Conference (APMC), 25-27, Nov. 4–7, 2014.

13. Kumar, S., C. Tannous, and T. Danshin, "A multisection broadband impedance transforming branch-line hybrid," IEEE Transactions on Microwave Theory and Techniques, Vol. 43, No. 11, 2517-2523, Nov. 1995.
doi:10.1109/22.473172

14. Alcon, P., N. Esparza, L. F. Herran, and F. Las Heras, "On the design of generic matching networks in reflective-type phase shifters for antennas," 2015 9th European Conference on Antennas and Propagation (EuCAP), 1-5, Lisbon, 2015.

15. Hee-Ran, A., "Complex impedance transformers consisting of only transmission-line sections," IEEE Transactions on Microwave Theory and Techniques, Vol. 60, No. 7, 2073-2083, July 2012.

16. Reed, J. and G. J. Wheeler, "A method of analysis of symmetrical four-port networks," IRE Transactions on Microwave Theory and Techniques, Vol. 4, No. 4, 246-252, October 1956.
doi:10.1109/TMTT.1956.1125071

17. Kurokawa, K., "Power waves and the scattering matrix," IEEE Transactions on Microwave Theory and Techniques, Vol. 13, No. 2, 194-202, March 1965.
doi:10.1109/TMTT.1965.1125964

18. Lind, L. F., "Synthesis of asymmetrical branch-guide directional coupler-impedance transformers (correspondence)," IEEE Transactions on Microwave Theory and Techniques, Vol. 17, No. 1, 45-48, January 1969.
doi:10.1109/TMTT.1969.1126879

Dr. Pablo Alcon Garcia

Dr. Nuria Esparza Lopez

Dr. Luis Herran Ontanon

Prof. Fernando Las Heras Andres