volume | PIER Journals

Abstract

A 3-dB compact hybrid coupler is presented in this paper in an ultra-wideband frequency range from 1.5 GHz to 3.2 GHz with 90˚ phase deference between the two output ports. The proposed coupler is formed by two notched elliptically shaped microstrip lines and four phase shifters, which are broadside coupled through an elliptically shaped slot. A combination of impedance matching technique and structural modification then has been employed to increase coupler efficiency. The design is demonstrated assuming a 0.51-mm-thick Rogers RO4350B substrate. Results of simulation and measurements show that the designed device exhibits a coupling of 3±1 dB across the aimed bandwidth. This ultra-wideband coupling is accompanied by smooth isolation in the order of better than 25 dB and return loss in the order of better than 17 dB. The manufactured device including microstrip ports and phase shifters occupy an area of 35 mm × 30 mm × 1.1 mm (0.27λ × 0.23λ × 0.009λ) which makes it a compact suitable device for UHF applications and measurements, specifically measuring and determining isolation in in-band full duplex transceivers, because of its smooth isolation versus frequency and ultra-wideband bandwidth.

1. Pozar, D. M., Microwave Engineering, 4th Edition, 2012.

2. Bialkowski, M. E. and A. P. Dimitrios, "A step-frequency six-port network analyser with a real-time display," AEU Int. J. Electron. Commun., Vol. 47, No. 3, 193-197, 1993. Google Scholar

3. Choi, M. K., M. Zhao, S. C. Hagness, and D. W. van Der Weide, "Compact mixer-based 1-12 GHz reflectometer," IEEE Microwave and Wireless Components Letters, Vol. 15, No. 11, 781-783, 2005.
doi:10.1109/LMWC.2005.859015 Google Scholar

4. Laughlin, L., et al. "Tunable frequency-division duplex RF front end using electrical balance and active cancellation," IEEE Transactions on Microwave Theory and Techniques, Vol. 66, No. 12, 5812-5824, 2018.
doi:10.1109/TMTT.2018.2851990 Google Scholar

5. Laughlin, L., M. A. Beach, K. A. Morris, and J. L. Haine, "Electrical balance duplexing for small form factor realization of in-band full duplex," IEEE Communications Magazine, Vol. 53, No. 5, 102-110, 2015.
doi:10.1109/MCOM.2015.7105648 Google Scholar

6. Laughlin, L., M. A. Beach, K. A. Morris, and J. L. Haine, "Optimum single antenna full duplex using hybrid junctions," IEEE Journal on Selected Areas in Communications, Vol. 32, No. 9, 1653-1661, 2014.
doi:10.1109/JSAC.2014.2330191 Google Scholar

7. Uysal, S. and A. H. Aghvami, "Synthesis and design of wideband symmetrical nonuniform couplers for MIC applications," IEEE MTT-S Int. Microw. Symp. Dig., 587-590, 1988. Google Scholar

8. Cho, J. H., H. Y. Hwang, and S. W. Yun, "A design of wideband 3-dB coupler with N-section microstrip tandem structure," IEEE Microwave and Wireless Components Letters, Vol. 15, No. 2, 113-115, 2005.
doi:10.1109/LMWC.2004.842850 Google Scholar

9. Lange, J., "Interdigitated stripline quadrature hybrid," IEEE Transactions on Microwave Theory and Techniques, Vol. 17, No. 12, 1150-1151, 1969.
doi:10.1109/TMTT.1969.1127115 Google Scholar

10. De Ronde, F. C., "A new class of microstrip directional couplers," IEEE MTT-S Int. Microw. Symp. Dig., 184-189, 1970. Google Scholar

11. Tanaka, T., K. Tsunoda, and M. Aikawa, "Slot-coupled directional couplers on a both-sided substrate MIC and their applications," Electronics and Communications in Japan (Part II: Electronics), Vol. 72, No. 3, 1989.
doi:10.1002/ecjb.4420720310 Google Scholar

12. Wong, M. F., V. Fouad Hanna, O. Picon, and H. Baudrand, "Analysis and design of slot-coupled directional couplers between double-sided substrate microstrip lines," IEEE MTT-S Int. Microw. Symp. Dig., 2123-2129, 1991. Google Scholar

13. Garcia, J. A., "A wideband quadrature hybrid coupler," IEEE Transactions on Microwave Theory and Techniques, Vol. 19, No. 7, 660-661, 1971.
doi:10.1109/TMTT.1971.1127598 Google Scholar

14. Schiek, B., "Hybrid branchline couplers --- A useful new class of directional couplers," IEEE Transactions on Microwave Theory and Techniques, Vol. 22, No. 10, 804-869, 1974.
doi:10.1109/TMTT.1974.1128365 Google Scholar

15. Hoffmann, R. K. and J. Siegl, "Microstrip-slot coupler design --- Part II: Practical design aspects," IEEE Transactions on Microwave Theory and Techniques, Vol. 30, No. 8, 1205-1216, 1982.
doi:10.1109/TMTT.1982.1131222 Google Scholar

16. Abbosh, A. M. and M. E. Bialkowski, "Design of compact directional couplers for UWB applications," IEEE Transactions on Microwave Theory and Techniques, Vol. 25, No. 22, 189-194, 2007.
doi:10.1109/TMTT.2006.889150 Google Scholar

17. Chang, C. P., J. C. Chiu, H. Y. Chiu, and Y. H.Wang, "A 3-dB quadrature coupler using broadside-coupled coplanar waveguides," IEEE Microwave and Wireless Components Letters, Vol. 18, No. 3, 191-193, 2008.
doi:10.1109/LMWC.2008.916805 Google Scholar

18. Malo-Gomez, I., J. D. Gallego-Puyol, C. Diez-Gonzalez, I. Lopez-Fernandez, and C. Briso- Rodriguez, "Cryogenic hybrid coupler for ultra-low-noise radio astronomy balanced ampliers," IEEE Transactions on Microwave Theory and Techniques, Vol. 57, No. 12, 3239-3245, 2009.
doi:10.1109/TMTT.2009.2033874 Google Scholar

19. Hayati, M. and M. Nosrati, "Loaded coupled transmission line approach of left-handed (LH) structures and realization of a highly compact dual-band branch-line coupler," Progress In Electromagnetics Research C, Vol. 10, 75-86, 2009.
doi:10.2528/PIERC09041508 Google Scholar

20. Nosrati, M., M. Daneshmand, and B. Virdee, "Novel compact dual-narrow/wideband branch- line couplers using T-Shaped stepped-impedance-stub lines," International Journal of RF and Microwave Computer-Aided Engineering, Vol. 21, No. 6, 642-649, 2011.
doi:10.1002/mmce.20559 Google Scholar

21. Sanada, A., C. Caloz, and T. Itoh, "Characteristics of the composite right/left-handed transmission lines," IEEE Microwave and Wireless Components Letters, Vol. 14, No. 2, 2004.
doi:10.1109/LMWC.2003.822563 Google Scholar

22. "CST studio suite electromagnetic field simulation software (2020),", DASSAULT SYSTEMES, [Online]. Available: https://www.3ds.com/products-services/simulia/products/cst-studio-suite/. Google Scholar

Dr. Soheyl Soodmand

Dr. Mark Beach

Dr. Kevin Morris