volume | PIER Journals

Abstract

In this letter, a new miniaturized broadband 3-dB branch-line coupler at the center frequency of 880 MHz is proposed. The proposed coupler is designed by means of integrated miniaturization method, which consists of shunt capacitors, fractal geometry and equivalent miniaturized stubs, to achieve 82% size reduction compared with the referenced coupler. The return loss and isolation are both under -20 dB over a 19% relative bandwidth. The proposed coupler is simulated, fabricated and measured. The measured results agree well with the simulated ones.

1. Riblet, G. P., "A directional coupler with very flat coupling," IEEE Transactions on Microwave Theory and Techniques, Vol. 26, No. 2, 70-74, 1978.
doi:10.1109/TMTT.1978.1129315 Google Scholar

2. Mayer, B. and R. KnÄochel, "Branch-line couplers with improved design flexibility and broad bandwidth," IEEE Transactions on Microwave Theory and Techniques, Vol. 32, 391-394, 1990. Google Scholar

3. Tanigawa, S., K. Hayashi, T. Fujii, T. Kawai, and I. Otha, "Tri-band/broadband matching techniques for 3-dB branch-line couplers," Proceeding of the 37th European Microwave Conference, 560-563, 2007. Google Scholar

4. Chen, W. L. and G. M. Wang, "Exact design of novel miniaturised fractal-shaped branch-line couplers using phase-equalising method," IET Microwaves, Antennas & Propagation, Vol. 2, No. 8, 773-780, 2007.
doi:10.1049/iet-map:20080074 Google Scholar

5. Jung, S.-C., R. Negra, and F. M. Ghannouchi, "A miniaturized double-stage 3 dB broadband branch-line hybrid coupler using distributed capacitors," IEEE APMC, 1323-1326, 2009. Google Scholar

6. Jung, S.-C., R. Negra, and F. M. Ghannouchi, "A Design methodolgy for miniaturized 3-dB branch-line hybrid couplers using distributed capacitors printed in the inner area," IEEE Transactions on Microwave Theory and Techniques, Vol. 56, No. 12, 2950-2953, 2008.
doi:10.1109/TMTT.2008.2007323 Google Scholar

7. Shamsinejad, S., M. Soleimani, and N. Komjani, "Novel enhanced and miniaturized 90^。 coupler for 3G EH mixers," Progress In Electromagnetics Research Letters, Vol. 3, 43-50, 2008.
doi:10.2528/PIERL08012702 Google Scholar

8. Tang, , C.-W. and M.-G. Chen, "Synthesizing microstrip branch-line couplers with predetermined compact size and bandwidth," IEEE Transactions on Microwave Theory and Techniques, Vol. 55, No. 9, 1926-1934, 2007.
doi:10.1109/TMTT.2007.904331 Google Scholar

9. Tang, C.-W., M.-G. Chen, and C.-H. Tsai, "Miniaturization of microstrip branch-line coupler with dual transmission lines," IEEE Microwave and Wireless Components Letters, Vol. 18, No. 3, 185-187, 2008.
doi:10.1109/LMWC.2008.916798 Google Scholar

10. Elhiwaris, M. Y. O., S. K. B. A. Rahim, U. A. K. Okonkwo, N. B. M. Jizat, and M. F. Jamlos, "Miniaturized size branch line coupler using open stubs with high-low impedances," Progress In Electromagnetics Research Letters, Vol. 23, 65-74, 2011. Google Scholar

Dr. Jun Zhu

Dr. Yonggang Zhou

Dr. Jianhua Liu