volume | PIER Journals

Abstract

A new broadband microstrip branch-line quadrature hybrid with very flat phase response is presented. The device is made by cascading four branch-line couplers with arbitrary power division. The novel design is based on the microstrip transposition of a broadband waveguide polariser [4]. Across a 32% bandwidth centred at 9.3 GHz, the RL and the IL are respectively -15 dB and -3 dB/-4 dB; the phase difference is very flat, i.e. 90°±1.5°.

1. Fox, A. G., "An adjustable wave-guide phase changer," Proc. IRE, Vol. 35, 1489-1498, Dec. 1947.
doi:10.1109/JRPROC.1947.234574

2. Sultan, N. B., "Generalized theory of waveguide differential phase sections and application to novel ferrite devices," IEEE Trans. Microw. Theory Tech., Vol. 19, No. 4, 348-357, Apr. 1971.
doi:10.1109/TMTT.1971.1127519

3. Pisano, G., et al., "A 90 GHz waveguide variable phase-shifter," IEEE Microw. Wire. Comp. Lett., Vol. 17, No. 3, 208-210, 2007.
doi:10.1109/LMWC.2006.890476

4. Pisano, G., et al., "A novel broadband Q-band polarizer with very flat phase response," Journal of Electromagnetic Waves and Applications, Vol. 26, No. 5-6, 707-715, 2012.
doi:10.1080/09205071.2012.710795

5. Harris, A. I., et al., "Design considerations for correlation radiometers," NRAO Green Bank Telescope Memo, Vol. 254, 2007.

6. Fowles, G. R., "Introduction to modern optics," 2nd Edition, Dover Publication, New York, 1989.

7. Ahn, H.-R., et al., "Arbitrary power division branch-line hybrid terminated by arbitrary impedances," Electron. Lett., Vol. 35, No. 7, 1999.
doi:10.1049/el:19990352

8. Hsu, C.-L., "Dual-band branch-line coupler with large power division ratios," Asia-Pacific Microw. Conf., 2088-2091, Singapore, 2009.

9. Hsu, C.-L., et al., "Miniaturized dual-band hybrid couplers with arbitrary power division ratios," IEEE Trans. Microw. Theory Tech., Vol. 57, No. 1, 2009.

10. Gwon, C., et al., "A new branch-line hybrid coupler with arbitrary power division ratio," Asia-Pacific Microw. Conf., 1-4, Bangkok, 2007.

11. Lin, T.-W., et al., "Distributed and lumped element realizations of wideband branch-line hybrids with arbitrary power division," Asia-Pacific Microw. Conf., 2112-2115, Singapore, 2009.

12. , , , Ansoft High Frequency Structure Simulator, www.ansoft.com.

13. , , , Trackwise, Unit 4B Delta Drive, Tewkesbury Business Park, Tewkesbury, Gloucestershire GL20 8HB, UK.

Dr. Adelaide Ladu

Dr. Giampaolo Pisano