volume | PIER Journals

Abstract

In this paper, a novel miniaturized microstrip branch-line coupler (BLC) with good harmonic suppression using radial stub loaded resonators is proposed. The novel structure has two significant advantages, which not only effectively reduces the occupied area to 10.3% of the conventional BLC at 0.5 GHz, but also has high 14th harmonic suppression performance. The measured results indicate that a bandwidth of more than 121 MHz has been achieved while the phase difference between S₂₁ and S₃₁ is within 90° ± 1.5°. The measured bandwidth of |S₂₁| and |S₃₁| within 3 ± 0.4 dB are 146 MHz and 151 MHz, respectively. Furthermore, the measured insertion loss is comparable to that of a conventional BLC. To validate the design concept, a new miniaturized planar BLC with good harmonic suppression using radial stub loaded resonators is designed and fabricated. Simulated and experimental results are achieved with good agreement.

1. Pozar, D. M., Microwave Engineering, 3rd Edition, Chap. 7, 333–337, Wiley, New York, 2005.

2. Mohra, A., A. F. Sheta, and S. F. Mahmoud, "New compact 3 dB 0/180 microstrip coupler configurations," Applied Computational Electromagnetics Society (ACES) Journal, Vol. 19, No. 2, 108-112, Jul. 2004.

3. Xiao, B., J. Hong, and B. Wang, "A novel UWB out-of-phase four-way power divider," Applied Computational Electromagnetics Society (ACES) Journal, Vol. 26, No. 10, 863-867, Oct. 2011.

4. Shamaileh, K. A., A. Qaroot, N. Dib, and A. Sheta, "Design of miniaturized unequal split Wilkinson power divider with harmonics suppression using non-uniform transmission lines," Applied Computational Electromagnetics Society Journal, Vol. 26, No. 6, 530-538, Jun. 2011.

5. Eccleston, K. W. and S. H. M. Ong, "Compact planar microstripline branch-line and rat-race couplers," IEEE Trans. Microw. Theory Tech., Vol. 51, No. 10, 2119-2125, Oct. 2003.
doi:10.1109/TMTT.2003.817442

6. Mondal, P. and A. Chakrabarty, "Design of miniaturized branch-line and rat-race hybrid couplers with harmonics suppression," IET Microw. Antennas Propag., Vol. 3, No. 1, 109-116, Jan. 2009.
doi:10.1049/iet-map:20070202

7. Gu, J. and X. Sun, "Miniaturization and harmonic suppression of branch-line and rat-race hybrid coupler using compensating spiral compact microstrip resonant cell," IEEE MTT-S Int. Dig., 1211-1214, 2005.

8. Wang, J., B.-Z. Wang, Y. X. Guo, L. C. Ong, and S. Xiao, "A compact slow-wave microstrip branch-line coupler with high performance," IEEE Microw. Wirel. Compon. Lett., Vol. 17, No. 7, 501-503, Jul. 2007.
doi:10.1109/LMWC.2007.899307

9. Velidi, V. K., B. Patel, and S. Sanval, "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, Jan. 2011.
doi:10.1002/mmce.20495

10. Tsai, K. Y., H. S. Yang, J. H. Chen, and Y. J. Chen, "A miniaturized 3 dB branch-line hybrid coupler with harmonics suppression," IEEE Microw. Wirel. Compon. Lett., Vol. 21, No. 10, 537-539, Oct. 2011.
doi:10.1109/LMWC.2011.2164901

11. Velidi, V. K., A. Pal, and S. Sanyal, "Harmonics and size reduced microstrip branch-line baluns using shunt open-stubs," International Journal of RF and Microwave Computer-Aided Engineering, Vol. 21, No. 2, 115-119, Mar. 2011.
doi:10.1002/mmce.20495

12. Sha, S., Y. Ye, and Z. Zhang, "A novel microstrip branch-line coupler with wide suppression band," Progress In Electromagnetics Research Letters, Vol. 83, 139-143, 2019.
doi:10.2528/PIERL19021003

13. Nosrati, M., "An extremely miniaturized microstrip branch-line coupler," Microw. Opt. Tech. Lett., Vol. 51, No. 6, 1403-1406, 2009.
doi:10.1002/mop.24365

14. Kurgan, P., A. Bekasiewicz, and M. Kitlinski, "Slow-wave resonant structures in branch-line coupler miniaturization: A case study," 19th International Conference on Microwaves, Radar & Wireless Communications, 695-698, 2012.

15. Wang, J. P., L. Ge, Y.-X. Guo, and W. Wu, "Miniaturised microstrip lowpass filter with broad stopband and sharp roll-off," IET Electronics Letters, Vol. 46, 573-575, 2010.
doi:10.1049/el.2010.0329

Dr. Hai Zhang

Dr. Zhijie Zhang