volume | PIER Journals

Abstract

Generalized synthesis of the rat race ring coupler is developed with its four arms being allowed to have different characteristic impedances. The transmission line theory incorporated with the even-odd analysis is used to formulate the conditions for solving the circuit parameters. The solution shows that a rat race ring with a normalized area of 41.82% or 0.97λ-circumference can be achieved. Based on the solutions, simulated bandwidths of the new ring hybrids are reported. Two experimental circuits are measured for validation check. One uses stepped-impedance sections to realize the four arms for further size reduction. This circuit occupies only 13.12% of that of a conventional hybrid ring at 1 GHz. It is believed that this implementation has the best size reduction for a microstrip ring hybrid in open literature. Measured scattering parameters show good agreement with the simulated results.

1. Ruiz-Cruz, J. A., J. R. Montejo-Garai, J. M. Rebollar, and S. Sobrino, "Compact full Kuband triplexer with improved E-plane power divider," Progress In Electromagnetics Research, Vol. 86, 39-51, 2008.
doi:10.2528/PIER08082803

2. Wu, Y., Y. Liu, and S. Li, "Dual-band modified Wilkinson power divider without transmission line stubs and reactive components," Progress In Electromagnetics Research, Vol. 96, 9-20, 2009.
doi:10.2528/PIER09072109

3. Wu, Y., Y. Liu, and S. Li, "An unequal dual-frequency Wilkinson power divider with optional isolation structure," Progress In Electromagnetics Research, Vol. 91, 393-411, 2009.
doi:10.2528/PIER09030501

4. Settaluri, R. K., G. Sundberg, A. Weisshaar, and V. K. Tripathi, "Compact folded line rat-race hybrid couplers," IEEE Microw. Guided Wave Lett., Vol. 10, No. 2, 61-63, Feb. 2000.
doi:10.1109/75.843101

5. Jung, S.-C., R. Negra, and F. M. Ghannouchi, "A design methodology for miniaturized 3-dB branch-line hybrid couplers using distributed capacitors printed in the inner area," IEEE Trans. Microw. Theory Tech., Vol. 56, No. 12, 2950-2953, Dec. 2008.
doi:10.1109/TMTT.2008.2007323

6. Hirota, T., A. Minakawa, and M. Muraguchi, "Reduced-size branch-line and rat-race hybrids for uniplanar MMICs," IEEE Trans. Microw. Theory Tech., Vol. 38, No. 3, 270-275, Mar. 1990.
doi:10.1109/22.45344

7. Adam, H., A. Ismail, M. A. Mahdi, M. S. Razalli, A. R. H. Alhawari, and B. K. Esfeh, "Xband miniaturized wideband bandpass filter utilizing multilayered microstrip hairpin resonator," Progress In Electromagnetics Research, Vol. 93, 177-188, 2009.
doi:10.2528/PIER09042202

8. Li, J.-F., B.-H. Sun, H.-J. Zhou, and Q.-Z. Liu, "Miniaturized circularly-polarized antenna using tapered meander-line structure," Progress In Electromagnetics Research, Vol. 78, 321-328, 2008.
doi:10.2528/PIER07090801

9. Shum, K. M., Q. Xue, and C. H. Chan, "A novel microstrip ring hybrid incorporating a PBG cell," IEEE Microw. Wireless Compon. Lett., Vol. 11, No. 6, 258-260, Jun. 2001.
doi:10.1109/7260.928931

10. Gu, J. and X. Sun, "Miniaturization and harmonic suppression rat-race coupler using C-SCMRC resonators with distributive equivalent circuit," IEEE Microw. Wireless Compon. Lett., Vol. 15, No. 12, 880-882, Dec. 2005.
doi:10.1109/LMWC.2005.859980

11. Fan, L., C.-H. Ho, S. Kanamaluru, and K. Chang, "Wide-band reduced-size uniplanar magic-T, hybrid-ring, and de Ronde's CPW-slot couplers," IEEE Trans. Microw. Theory Tech., Vol. 43, No. 12, 2149-2158, Dec. 1995.

12. Wang, T. and K.Wu, "Size-reduction and band-broadening design technique of uniplanar hybrid ring coupler using phase inverter for M(H)MIC's," IEEE Trans. Microw. Theory Tech., Vol. 47, No. 2, 198-206, Feb. 1999.
doi:10.1109/22.744295

13. Kao, C.-W. and C.-H. Chen, "Novel uniplanar 180°hybrid-ring couplers with spiral-type phase inverters," IEEE Microw. Guided Wave Lett., Vol. 10, No. 10, 412-414, Oct. 2000.

14. Sung, Y. J., C. S. Ahn, and Y.-S. Kim, "Size reduction and harmonic suppression of rat-race hybrid coupler using defected ground structure," IEEE Microw. Wireless Compon. Lett., Vol. 14, No. 1, 7-9, Jan. 2004.
doi:10.1109/LMWC.2003.821499

15. Chun, Y.-H. and J.-S. Hong, "Compact wide-band branch-line hybrids," IEEE Trans. Microw. Theory Tech., Vol. 54, No. 2, 704-709, Feb. 2006.
doi:10.1109/TMTT.2005.862657

16. Eccleston, K. W. and S. H. M. Ong, "Compact planar microstripline branch-line and rat-race coupler," IEEE Trans. Microw. Theory Tech., Vol. 51, 2119-2125, Oct. 2003.

17. Kim, D. I. and G. S. Yang, "Design of new hybrid-ring directional coupler using λ/8 or λ/6 sections," IEEE Trans. Microw. Theory, Vol. 39, No. 10, 1779-1783, Oct. 1991.

18. Kuo, J.-T., J.-S. Wu, and Y.-C. Chiou, "Miniaturized rat race coupler with suppression of spurious passband," IEEE Microw. Wireless Compon. Lett., Vol. 17, No. 1, 46-48, Jan. 2007.
doi:10.1109/LMWC.2006.887254

19. Hsu, C.-L., J.-T. Kuo, and C.-W. Chang, "Miniaturized dual-band hybrid couplers with arbitrary power division ratios," IEEE Trans. Microw. Theory Tech., Vol. 57, No. 1, 149-156, Jan. 2009.
doi:10.1109/TMTT.2008.2009036

20. Mandal, M. K. and S. Sanyal, "Reduced-length rat-race couplers," IEEE Trans. Microw. Theory Tech., Vol. 55, No. 12, 2593-2598, Dec. 2007.
doi:10.1109/TMTT.2007.910058

21. Murgulescu, M.-H., E. Penard, and I. Zaquine, "Design formulas for generalised 180°hybrid ring couplers," Electron. Lett., Vol. 30, No. 7, 573-574, Mar. 1994.
doi:10.1049/el:19940415

22. IE3D Simulator, Zeland Software Inc., Jan. 1997.

Prof. Jen-Tsai Kuo

Dr. Cheng-Hsiu Tsai