volume | PIER Journals

Abstract

A three-section branch-line coupler is miniaturized using diamond-series stubs microstrip lines. The modified coupler is capable of operating from 1.6 GHz to 3 GHz with a return loss of less than -20 dB, phase imbalance of less than 2.5°, insertion loss and coupling of 4.5 dB and 3.02 dB, respectively. The bandwidth of the coupler has been extended up to 1.4 GHz. In addition, it achieves up to 84% size reduction as compared to a conventional three-section coupler. Furthermore, its performance and circuit size were compared with another modified coupler with normal open-stubs microstrip lines. Effects of the diamond structure and number of stubs were analyzed and discussed in detail, Furthermore, the results achieved by this study are superior to the previous studies.

1. Pozar, D. M., Microwave Engineering, 2nd Ed., Wily, New York, 1998.

2. Muraguchi, M., T. Yukitake, and Y. Naito, "Optimum design of 3-dB branch-line couplers 2 using microstrip lines," IEEE Trans. Microw. Theory Tech., Vol. 31, No. 8, 674-678, 1983.
doi:10.1109/TMTT.1983.1131568

3. Liao, S. S., P. T. Sun, N. C. Chin, and J. T. Peng, "A novel compact-size branch-line coupler," IEEE Trans. Microwave and Wireless Components Letters, Vol. 15, No. 9, 588-590, 2005.
doi:10.1109/LMWC.2005.855378

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

5. Chen, W. L., G. M. Wang, and C. X. Zhang, "Miniaturization of wideband branch-line couplers using fractal-shaped geometry," Microwave and Optical Technology Letters, Vol. 51, No. 1, 26-29, 2009.
doi:10.1002/mop.24002

6. Krishna, V. V., B. Patel, and S. Sanyal, "Harmonic suppressed compact wideband branch-line coupler using unequal length open-stub units," International Journal of RF and Microwave Computer Aided Engineering, Vol. 21, No. 1, 115-119, 2010.

7. Kurgan, P. and M. Kitlinski, "Novel doubly perforated broadband microstrip branch-line couplers," Microwave and Optical Technology Letters, Vol. 51, No. 9, 2149-2152, 2009.
doi:10.1002/mop.24566

8. Dwari, S. and S. Sanyal, "Size reduction and harmonic suppression of microstrip branch-line coupler using defected ground structure," Microwave and Optical Technology Letters, Vol. 48, No. 10, 1966-1969, Jul. 2006.
doi:10.1002/mop.21830

9. Sa’ad, B. M., S. K. Rahim, and R. Dewan, "Compact wide-band branch-line coupler with meander line, cross, and two-step stubs," Microwave and Optical Technology Letters, Vol. 5, No. 8, 1810-1815, Aug. 2013.
doi:10.1002/mop.27731

10. 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

11. Kim, H., B. Lee, and M. J. Park, "Dual-band branch-line coupler with port extensions," IEEE Trans. Microw. Theory Tech., Vol. 58, No. 3, 651-655, Mar. 2010.
doi:10.1109/TMTT.2010.2040342

12. Lee, S. and Y. Lee, "Wideband branch-line couplers with single-section quarter-wave transformers for arbitrary coupling levels," IEEE Microw. Wireless Compon. Lett., Vol. 22, No. 1, 19-21, Jan. 2012.
doi:10.1109/LMWC.2011.2176723

13. Wu, Y., J. Shen, and Y. Liu, "Comments on quasi-arbitrary phase-difference hybrid coupler," IEEE Trans. Microw. Theory Tech., Vol. 61, No. 4, 1725-1727, Apr. 2013.
doi:10.1109/TMTT.2013.2247771

14. Chiu, L. and Q. Xue, "Investigation of a wideband 90◦ hybrid coupler with an arbitrary coupling level," IEEE Trans. Microw. Theory Tech., Vol. 58, No. 4, 1022-1029, Aug. 2010.
doi:10.1109/TMTT.2010.2042835

15. Zong, B. F., G. M. Wang, C. X. Zhang, and Y. W. Wang, "Miniaturised branch-line coupler with ultra-wide high suppression stopband," Electron. Lett., Vol. 50, No. 19, 1365-1367, Sep. 2014.
doi:10.1049/el.2014.1150

16. Bekasiewicz, A. and S. Koziel, "Miniaturised dual-band branch-line coupler," Electron. Lett., Vol. 51, No. 10, 769-771, 2015.
doi:10.1049/el.2015.0751

17. Lee, J., J. Lee, and M.-J. Park, "Branch-line couplers with arbitrary coupling value through the electrical length variation with fixed line impedances," IEEE Microw. Wireless Compon. Lett., Vol. 27, No. 11, 968-970, 2017.
doi:10.1109/LMWC.2017.2750084

18. Zhou, B., H. Wang, and W.-X. Sheng, "A modified UWB Wilkinson power divider using delta stub," Progress In Electromagnetics Research Letters, Vol. 19, 49-55, 2010.
doi:10.2528/PIERL10101805

19. Alqahtani, B. M., A. F. Sheta, and andM. A. Alkanhal, "New compact wide-band branch-line couplers," IEEE Microwave Conference, 2009, EuMC 2009, European, 2009.

20. You, K. Y., A. A. Nadera, J. C. Chong, K. Y. Lee, E. M. Cheng, and Y. S. Lee, "Analytical modeling of conventional and miniaturization three-section branch-line couplers," Journal of Electrical Engineering & Technology, Vol. 13, No. 2, 858-867, 2018.

Ms. Nadera Najib Al-Areqi

Dr. You Kok Yeow

Dr. Mohamad Ngasri Dimon

Dr. Nor Hisham Khamis

Dr. Chia Yew Lee