DOI QR코드

DOI QR Code

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

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.

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, "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
  4. 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
  5. 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
  6. W. W. Munford, "Directional couplers", Proc. IRE., vol. 35, pp. 159-165, Feb. 1947
  7. R. G. Brown, R. A. Sharpe, W. L. Hughes, and R. E. Post, Lines, Waves and Antennas, Wiley, pp.124-128, 1973
  8. 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
  9. 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
  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. 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
  12. 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
  13. 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
  14. 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
  15. J. Helszajn, Passive and Active Microwave Circuits, John Wiley & Sons INC., p. 7, 1978
  16. 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
  17. H.-R. Ahn, Asymmetric Passive Components in Microwave Integrated Circuits, John Wiley & Sons INC., p. 65, Aug. 2006
  18. 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
  19. 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
  20. 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
  21. D. M. Pozar, Microwave Engineering, AddisonWesley, p. 185, Jun. 1990
  22. 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
  23. J. A. G. Malherbe, Microwave Transmission Line Couplers, Artech, p. 23, 1988
  24. 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
  25. 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
  26. 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
  27. R. Mongia, I. Bahl, and P. Bhartia, RF and Microwave Coupled-Line Circuits, Boston, Artech House INC., p. 190, 1999
  28. 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

Cited by

  1. Reply to Comments on “Wideband Coupled-Line Microstrip Filters With High-Impedance Short-Circuited Stubs” vol.22, pp.11, 2012, https://doi.org/10.1109/LMWC.2012.2225608
  2. Wideband Coupled-Line Microstrip Filters With High-Impedance Short-Circuited Stubs vol.21, pp.11, 2011, https://doi.org/10.1109/LMWC.2011.2167139
  3. Wideband Microstrip Coupled-Line Ring Hybrids for High Power-Division Ratios vol.61, pp.5, 2013, https://doi.org/10.1109/TMTT.2013.2251654
  4. Control of Phase and Phase Slope with Reinvestigation of 1D CRLH Transmission Lines vol.12, pp.4, 2012, https://doi.org/10.5515/JKIEES.2012.12.4.280