Journal of electromagnetic engineering and science

The Korean Institute of Electromagnetic Engineering and Science (한국전자파학회)
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Equivalent Transmission-Line Sections for Very High Impedances and Their Application to Branch-Line Hybrids with Very Weak Coupling Power

  • Ahn, Hee-Ran (Dept. of Electronics and Electrical Engineering, POSTECH(Pohang University of Science and Technology)) ;
  • Kim, Bum-Man (Dept. of Electronics and Electrical Engineering, POSTECH(Pohang University of Science and Technology))
  • Published : 2009.06.30
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Abstract

As operating frequency is raised and as more integration with active and passive elements is required, it becomes difficult to fabricate more than 120 ${\Omega}$ characteristic impedance of a mierostrip line. To solve this problem, an equivalent high impedance transmission-line section is suggested, which consists mainly of a pair of coupled-line sections with two shorts. However, it becomes a transmission-line section only when its electrical length is fixed and its coupling power is more than half. To have transmission-line characteristics(perfect matching), independently of coupling power and electrical length, two identical open stubs are added and conventional design equations of evenand odd-mode impedances are modified, based on the fact that the modified design equations have the linear combinations of conventional ones. The high impedance transmission-line section is a passive component and therefore should be perfectly matched, at least at a design center frequency. For this, two different solutions are derived for the added open stub and two types of high impedance transmission-line sections with 160 ${\Omega}$ characteristic impedance are simulated as the electrical lengths of the coupled-line sections are varied. The simulation results show that the determination of the available bandwidth location depends on which solution is chosen. As an application, branch-line hybrids with very weak coupling power are investigated, depending on where an isolated port is located, and two types of branch-line hybrids are derived for each case. To verify the derived branch-line hybrids, a microstrip branch-line hybrid with -15 dB coupling power, composed of two 90$^{\circ}$ and two 270$^{\circ}$ transmission-line sections, is fabricated on a substrate of ${\varepsilon}_r$= 3.4 and h=0.76 mm and measured. In this case, 276.7 ${\Omega}$ characteristic impedance is fabricated using the suggested high impedance transmission-line sections. The measured coupling power is -14.5 dB, isolation and matching is almost perfect at a design center frequency of 2 GHz, showing good agreement with the prediction.

Keywords

References

  1. H. A. Wheeler, "Transmission-line properties of a strip on a dielectric sheet on a plane", IEEE Trans. Microwave Theory Tech., vol. 25, no. 8, pp. 631-647, Aug. 1977 https://doi.org/10.1109/TMTT.1977.1129179
  2. H. A. Wheeler, "Transmission-line properties of parallel strips separated by a dielectric sheet", IEEE Trans. Microwave Theory Tech., vol. 3, no. 3, pp.172-185, Mar. 1965
  3. S. B. Cohn, R. Levy, "History of microwave passive components with particular attention to directional couplers", IEEE Trans. Microwave Theory Tech., vol. MTT-32, pp. 1046-1054, Sep. 1984 https://doi.org/10.1109/TMTT.1984.1132816
  4. E. M. T. Hones, J. T. Bolljahn, "Coupled-strip- transmission-line filters and directional couplers", IRE Trans. Microwave Theory Tech., vol. MTT-4, pp.75-81, Apr. 1956 https://doi.org/10.1109/TMTT.1956.1125022
  5. S. B. Cohn, "Parallel-coupled transmission line resonators", IRE Trans. Microwave Theory Tech., vol. MTT-6, pp. 223-231, Apr. 1958 https://doi.org/10.1109/TMTT.1958.1124542
  6. G. L. Matthaei, "Interdigital bandpass filters", IRE Trans. Microwave Theory Tech., vol. MTT -10, pp. 479-491, Nov. 1962 https://doi.org/10.1109/TMTT.1962.1125556
  7. R. Levy, "General synthesis of asymmetric multielement coupled transmission line directional couplers", IEEE Trans. Microwave Theory Tech., vol. MTT-11, pp. 227-231, Jul. 1963
  8. V. J. Tripathi, "Asymmetric coupled transmission lines in an inhomogeneous medium", IEEE Trans. Microwave Theory Tech., vol. MTT-23 , pp. 734-739, Sep. 1975 https://doi.org/10.1109/TMTT.1975.1128665
  9. H. -R. Ahn, B. Kim, "Transmission-line directional couplers for impedance transforming", IEEE Microwave and Wireless Components Letters, pp. 537-539, Oct. 2006 https://doi.org/10.1109/LMWC.2006.882404
  10. H.- R. Ahn, B. Kim, "Toward integrated circuit size reduction", IEEE Microwave Magazine, pp. 65-75, Feb. 2008 https://doi.org/10.1109/MMM.2007.910937
  11. S. March, "A wideband strip line hybrid ring", IEEE Trans. Microwave Theory Tech., vol. MTT-16, pp. 361-362, Jun. 1968 https://doi.org/10.1109/TMTT.1968.1126693
  12. L. K. Yeung, K. L. Wu, "A dual-band coupled-line balun filter", IEEE Trans. Microwave Theory Tech., vol. 55, no. 11, pp. 2406-2411, Nov. 2007 https://doi.org/10.1109/TMTT.2007.907402
  13. X. Gao, L. K. Yeung, and K. L. Wu, "A dual-band balun using partially coupled stepped-impedance coupled-line resonators", IEEE Trans. Microwave Theory Tech., vol. 55, no. 11, pp. 1455-1460, Jun. 2008
  14. R. Phromloungsri, M. Chongcheawchamnan, and I. D. Robertson, "Inductively compensated parallel coupled microstrip lines and their applications", IEEE Trans. Microwave Theory Tech., vol. 54, no. 9, pp. 3571-3582, Sep. 2006 https://doi.org/10.1109/TMTT.2006.881026
  15. H. Hayasho, T. Nakagawa, and K. Araki, "A miniaturized MMIC analog phase shifter using two quarter-wave-Iength transmission lines", IEEE Trans. Microwave Theory Tech., vol. 50, no. 1, pp. 150-154, Jan. 2002 https://doi.org/10.1109/22.981259
  16. W. W. Munford, "Directional couplers", Proc. IRE., vol. 35, pp. 159-165, Feb. 1947
  17. H.-R. Ahn, I. Wolff., "Asymmetric four-port and branch-line hybrids", IEEE Trans. Microwave Theory Tech., vol. 48, pp. 1585-1588, Sep. 2000 https://doi.org/10.1109/22.869013
  18. D. M. Pozar, Microwave Engineering, AddisonWesley, p. 185, Jun. 1990
  19. H.-R. Ahn, Asymmetric Passive Components in Microwave Integrated Circuits, John Wiley & Sons INC., p. 65, Aug. 2006
  20. R. Mongia, I. Bahl, and P. Bhartia, RF and Microwave Coupled-Line Circuits, Boston, Artech House INC., p. 190, 1999
  21. J. Helszajn, Passive and Active Microwave Circuits, John Wiley & Sons INC., p. 7, 1978
  22. D. Kajfez, B. S. Vidula, "Design equations for symmetric microstrip DC blocks", IEEE MTT, vol. MTT-28, no. 9, pp. 974-981, Sep. 1980 https://doi.org/10.1109/TMTT.1980.1130205
  23. R. G. Brown, R. A. Sharpe, W. L. Hughes, and R. E. Post, Lines, Waves and Antennas, Wiley, pp.124-128, 1973
  24. J. A. G. Malherbe, Microwave Transmission Line Couplers, Artech, p. 23, 1988
  25. R. K. Gupta, S. E. Anderson, and W. Getsinger, "Impedance-transforming 3-dB hybrids", IEEE Trans. Microwave Theory Tech., vol. MTT-35, pp. 1303-1307, Dec. 1987 https://doi.org/10.1109/TMTT.1987.1133852
  26. S. Kummar, C. Tannous, and T. Danshin, "A multisection broadband impedance transforming branch line hybrid", IEEE Trans. Microwave Theory Tech., vol. 43, pp. 2517-2523, Nov. 1995 https://doi.org/10.1109/22.473172
  27. L. F. Lind, "Synthesis of asymmetrical branch-guided directional coupler-impedance transformers", IEEE Trans. Microwave Theory Tech., vol. MTT-17, pp. 45-48, Jan. 1969 https://doi.org/10.1109/TMTT.1969.1126879
  28. H. R. Ahn, J. Kim, and B. Kim, "Branch-line hybrids with -15 dB coupling power", in APMC 2008 CD, Bl-3 paper, Hong Kong, Dec. 2008

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