The Journal of Korean Institute of Electromagnetic Engineering and Science (한국전자파학회논문지)

The Korean Institute of Electromagnetic Engineering and Science (한국전자파학회)
권호 표지
DOI QR코드

DOI QR Code

Compact and Wideband Coupled-Line 3-dB Ring Hybrids

Coupled Line으로 구성된 작고 넓은 대역폭을 가지는 3-dB Ring Hybrids

  • Ahn, Hee-Ran (Dept. of Electronics and Electrical Engineering, Pohang University of Science and Technology(POSTECH)) ;
  • Kim, Jung-Joon (Dept. of Electronics and Electrical Engineering, Pohang University of Science and Technology(POSTECH)) ;
  • Kim, Bum-Man (Dept. of Electronics and Electrical Engineering, Pohang University of Science and Technology(POSTECH))
  • 안희란 (포항공과대학교 전자전기공학과) ;
  • 김정준 (포항공과대학교 전자전기공학과) ;
  • 김범만 (포항공과대학교 전자전기공학과)
  • Published : 2008.08.31
Download PDF
⟨ Previous Next ⟩

Abstract

In this paper, two types of wideband 3-dB ring hybrids are compared and discussed to show the ring hybrid with a set of coupled-line sections better. However, the better one still has a realization problem that perfect matching can be achieved only with -3 dB coupling power. To solve the problem, a set of coupled-line sections with two shorts is synthesized using one- and two-port equivalent circuits and design equations are derived to have perfect matching, regardless of the coupling power. Based on the design equations, a modified ${\Pi}-type$ of transmission-line equivalent circuit is newly suggested. It consists of coupled-line sections with two shorts and two open stubs and can be used to reduce a transmission-line section, especially when its electrical length is greater than ${\pi}$. Therefore, the $3\;{\lambda}/4$ transmission-line section of a conventional ring hybrid can be reduced to less than ${\pi}/2$. To verify the modified ${\Pi}-type$ of transmission- line equivalent circuit, two kinds of simulations are carried out; one is fixing the electrical length of the coupled-line sections and the other fixing its coupling coefficient. The simulation results show that the bandwidths of resulting small transmission lines are strongly dependent on the coupling power. Using modified and conventional ${\Pi}-types$ of transmission-line equivalent circuits, a small ring hybrid is built and named a compact wideband coupled-line ring hybrid, due to the fact that a set of coupled-line sections is included. One of compact ring hybrids is compared with a conventional ring hybrid and the compared results demonstrate that the bandwidth of a proposed compact ring hybrid is much wider, in spite of being more than three times smaller in size. To test the compact ring hybrids, a microstrip compact ring hybrid, whose total transmission-line length is $220^{\circ}$, is fabricated and measured. The measured power divisions($S_{21}$, $S_{41}$, $S_{23}$ and $S_{43}$) are -2.78 dB, -3.34 dB, -2.8 dB and -3.2 dB, respectively at a design center frequency of 2 GHz, matching and isolation less than -20 dB in more than 20 % fractional bandwidth.

두 종류의 넓은 대역폭을 갖는 ring hybrids(하나는 coupled line이 포함되어 있고, 다른 하나는 left-handed transmission line을 포함한 ring hybrids)가 비교되었으며, 비교 결과로부터 coupled line을 포함한 ring hybrid가 모든 면에서 우수한 특성을 가짐을 보여줬다. 그러나, coupled line을 포함한 ring hybrid는 -3 dB coupling power를 가질 경우에 한해서만이 perfect matching이 이루어지기 때문에, perfect matching을 갖는 coupled line ring hybrid는 2차원으로 구현하기는 거의 불가능하다. 이 문제를 해결하기 위해서 coupled line을 해석했고, 그 해석 결과로부터 coupling coefficient에 관계없이 어느 경우에도 perfect matching을 이룰 수 있는 설계 식을 유도했다. 이 설계식을 이용하여, transmission line의 길이가 ${\pi}$보다 큰 경우에도 적용될 수 있는 크기를 줄이기 위한 새로운 형태의 transmission line 등가회로를 제시했다. 이 새로운 형태의 transmission line의 등가회로를 이용하면 기존의 ring hybrid의 $3\;{\lambda}/4$의 transmission line을 줄이는 데 사용할 수 있기 때문에 ring hybrid의 크기를 더욱 줄이는데 장점이 될 수 있다. 이 등가회로를 증명하기 위해서, coupling power를 고정하고 또는 transmission line의 길이를 고정하는 2가지 형태의 simulation을 하였으며, 대역폭은 coupled line의 coupling power에 직접적인 상관 관계가 있음을 보였다. 기존의 등가회로와 새로운 형태의 등가회로를 이용하여, 작고 넓은 대역폭을 가지는 ring hybrid를 제시하였다. 새로 제시된 ring hybrid를 이용하여, 기존의 ring hybrid와 비교하였다. 비교 결과로부터, 본 논문에서 제시한 ring hybrid의 전체 ring 둘레가 1/3보다 더 작음에도 불구하고, 대역폭이 훨씬 넓음을 보여줬다. 작고 넓은 대역폭을 가지는 ring hybrid를 측정했으며, 측정 결과는 -2.78 dB, -3.34 dB, -2.8 dB, -3.2 dB의 power division 특성을 보여줬으며, matching과 isolation은 20 % 이상의 대역폭에서 -20 dB보다 좋은 특성을 보여줬다.

Keywords

References

  1. W. A. Tyrrel, 'Hybrid circuits for microwaves', Proc. IRE., vol. 35, pp. 1294-1306, Nov. 1947 https://doi.org/10.1109/JRPROC.1947.233572
  2. V. I. Albanese, W. P. Peyser, 'An analysis of a broad-band coaxial hybrid ring', IRE Trans. Microwave Theory Tech., vol. 6, pp. 369-373, Oct. 1958 https://doi.org/10.1109/TMTT.1958.1125207
  3. W. V. Tyminski, A. E. Hylas, 'A wide-band hybrid ring for UHF', Proc. IRE., pp. 81-87, Jan. 1953
  4. S. March, 'Wideband stripline hybrid ring', IEEE Trans. Microwave Theory Tech., vol. MTT-16, pp. 361-362, Jun. 1968
  5. L. K. Yeung, Y. E. Wang, 'A novel 180$circ$ hybrid using broadside-coupled asymmetric coplanar striplines', IEEE Trans. Microwave Theory Tech., vol. 55, pp. 2625-2630, Dec. 2007 https://doi.org/10.1109/TMTT.2007.910067
  6. C. -H. Chi, C. -Y. Chang, 'A new class of wideband multiseciton 180$\circ$ hybrid rings vertically installed planar couplers', IEEE Trans. Microwave Theory Tech., vol. 54 pp. 2478-2486, Jun. 2006 https://doi.org/10.1109/TMTT.2006.875799
  7. H. -R. Ahn, Ingo Wolff, and Ik-Soo Chang, 'Arbitrary termination impedances, arbitrary power division and small-sized ring hybrids', IEEE Trans. Microwave Theory Tech., vol. 45, pp. 2241-2247, Dec. 1997 https://doi.org/10.1109/22.643824
  8. C. -H. Ho, L. Fan, and K. Chang, 'Broad-band uniplanar hybrid-ring and branch-line couplers', IEEE Trans. Microwave Theory Tech., vol. 41, pp. 2116- 2124, Dec. 1993 https://doi.org/10.1109/22.260695
  9. C. -H. Ho, L. Fan, and K. Chang, 'Slotline annular ring elements and their applications to resonator, filter and coupler design', IEEE Trans. Microwave Theory Tech., vol. 41, pp. 1648-1650, Sep. 1993 https://doi.org/10.1109/22.245694
  10. C. -H. Ho, L. Fan, and K. Chang, 'New uniplanar coplanar waveguide hybrid-ring couplers and magic-T's', IEEE Trans. Microwave Theory Tech., vol. 42, pp. 2440-2448, Dec. 1994 https://doi.org/10.1109/22.339779
  11. H. Okabe, C. Caloz, and T. Itoh, 'A compact enhanced-bandwidth hybrid ring using an artificial lumped-element left-handed transmission line section', IEEE Trans. Microwave Theory Tech., vol. 52, pp. 798-804, Mar. 2004 https://doi.org/10.1109/TMTT.2004.823541
  12. L. Fan, C. -H, Ho, S. Kanamaluru, and K. Chang, 'Wide-band reduced sized uniplanar magic-T hybrid ring and de Ronde's CPW-slot couplers', IEEE Trans. Microwave Theory Tech., vol. 43, pp. 2749- 2758, Dec. 1995 https://doi.org/10.1109/22.475631
  13. B. -H. Murgulescu, E. Moisan, P. Leaude, E. Penard, and I. Zaquine, 'New wideband 0.67 $\lambda$g circumference 180$\circ$ hybrid ring coupler', Electronic Lett., vol. 30, no. 4, pp. 299-300, Feb. 1994 https://doi.org/10.1049/el:19940234
  14. T. Hirota, A. Minakawa, and M. Muraguchi, 'Reduced-size branch-line and rat-race hybrids for uniplanar MMIC's', IEEE Trans. Microwave Theory Tech., vol. 38, pp. 270-275, Mar. 1990 https://doi.org/10.1109/22.45344
  15. M. -L. Chung, 'Miniaturized ring coupler of arbitrary reduced size', IEEE. Microwave Component Lett., vol. 15, no. 1, pp. 16-18, Jan. 2005 https://doi.org/10.1109/LMWC.2004.840960
  16. H. -R. Ahn, AsymmetrIc Passive Components in Microwave Integrated Circuits, New York, John Wiley & Sons, Inc., Aug. 2006
  17. H. -R. Ahn, I. -S. Chang and S. -W. Yun, 'Miniaturized 3-dB ring hybrid terminated by arbitrary impedances', IEEE Trans. Microwave Theory Tech., vol. 42, pp. 2216-2241, Dec. 1994 https://doi.org/10.1109/22.339745
  18. S. J. Parisi, '180$\circ$ lumped element hybrid', in IEEE MTT-S Dig., pp. 1243-1246, 1989
  19. R. K. Gupta, W. J. Gestinger, 'Quasi-lumped-element 3- and 4-port networks for MIC an MMIC applications', in IEEE MTT-S Dig., pp. 409-411, 1984
  20. H. -R. Ahn, B. Kim, 'Transmission-line directional couplers for impedance transforming', IEEE Microwave and Wireless Components Letters, pp. 537-539, Oct. 2006
  21. H. -R. Ahn, B. Kim, 'Toward integrated circuit size reduction', IEEE Microwave Magazine, pp. 65-75, Feb. 2008
  22. H. -R. Ahn, Resonators, in Encyclopedia of RF and Microwave Engineering, Wiley, 2005
  23. G. Mathaei, L. Young, and E. M. T. Jones, Microwave Filters, Impedance-Matching Networks and Coupling Structures, Artech House, NJ, USA, pp. 36, 1985
  24. Y. Konishi, I. Awai, Y. Fukuka and M. Nakajima, 'A directional coupler of a vertically installed planar circuit structure', IEEE Trans. Microwave Theory Tech., vol. 36, pp. 1057-1063, Jun. 1988 https://doi.org/10.1109/22.3632