A power divider with ultra-wideband (UWB) performance has been designed. The quarter-wave transformer in the conventional Wilkinson power divider is replaced by an exponentially tapered microstrip line. Since the tapered line provides a consistent impedance transformation across all frequencies, very low amplitude ripple of 0.2 dB peak-to-peak in the transmission coefficient and superior input return loss better than 15 dB are achieved over an ultra-wide bandwidth. Two additional resistors are added along the tapered line to improve the output return loss and isolation. Simulation performed using CST Microwave Studio and measured results confirm the good performance of the proposed circuit. The return loss and the isolation between the output ports are better than 15 dB across the band 2-10.2 GHz. Standard off-the-shelf resistance values can be selected by optimizing the physical locations to mount the resistors. Better performance can be achieved with more isolation resistors added. Hence, the number of isolation resistors to be used may be selected based on the desired bandwidth and level of isolation and return loss specifications.
2. Cohn, S. B., "A class of broadband three-port TEM-mode hybrids," IEEE Trans. Microwave Theory Tech., Vol. 16, No. 2, 110-116, Feb. 1968.
doi:10.1109/TMTT.1968.1126617
3. Collin, R. E., "Theory and design of wide-band multisection quarter-wave transformers," Proc. IRE, Vol. 43, 179-185, Feb. 1955.
doi:10.1109/JRPROC.1955.278076
4. Cohn, S. B., "Optimum design of stepped transmission-line transformers," IRE Trans. Microwave Theory Tech., Vol. 3, 16-21 , Apr. 1955.
doi:10.1109/TMTT.1955.1124940
5. Nishikawa, K., T. Tokumitsu, and I. Toyoda, "Miniaturized Wilkinson power divider using three-dimensional MMIC technology," IEEE Microw. Guided Wave Lett., Vol. 6, No. 10, 372-374, Oct. 1996.
doi:10.1109/75.536949
6. Lu, L. H., P. Bhattacharya, L. P. B. Katehi, and G. E. Ponchak, "X-band and K-band lumped Wilkinson power dividers with a micro-machined technology," EEE MTT-S Int. Dig., 287-290, 2000.
7. Parisi, S. J., "180° lumped element hybrid," IEEE MTT-S Int. Dig.,, 1243-1246, 1989.
doi:10.1109/MWSYM.1989.38951
8. Chongcheawchamnan, M., N. Siripon, and I. D. Robertson, "Design and performance of improved lumped-distributed Wilkinson divider topology," Electron. Lett., Vol. 37, 501-503, Apr. 2001.
doi:10.1049/el:20010356
9. Scardelletti, M. C., G. E. Ponchak, and T. M. Weller, "Miniaturized Wilkinson power dividers utilizing capacitive loading," IEEE Microw. Wireless Compon. Lett., Vol. 12, No. 1, 6-8, Jan. 2002.
doi:10.1109/7260.975717
10. Huang, W., C. Liu, L. Yan, and K. Huang, "A miniaturized dual-band power divider with harmonic suppression for GSM applications," Journal of Electromagnetic Waves and Applications, Vol. 24, No. 1, 81-91, 2010.
doi:10.1163/156939310790322082
11. Zhang, Z., Y.-C. Jiao, Y. Song, H.-H. Xie, S. Tu, and F. S. Zhang, "A compact 1 to 2 Wilkinson power divider for 2.4GHz/UWB with band-notched characteristic using simple defected ground structure," Journal of Electromagnetic Waves and Applications, Vol. 23, No. 11-12, 1623-1630, 2009.
12. Hosseini, F., M. Khalaj-Amir Hosseini, and M. Yazdani, "A miniaturized Wilkinson power divider using nonuniform transmission line," Journal of Electromagnetic Waves and Applications, Vol. 23, No. 7, 917-924, 2009.
doi:10.1163/156939309788355243
13. Lin, Z. and Q.-X. Chu, "A novel compact UWB power divider for spatial power combining," Journal of Electromagnetic Waves and Applications, Vol. 23, No. 13, 1803-1812, 2009.
doi:10.1163/156939309789566851
14. Wu, Y., Y. Liu, and S. Li, "A new dual-frequency Wilkinson power divider," Journal of Electromagnetic Waves and Applications, Vol. 23, No. 4, 483-492, 2009.
doi:10.1163/156939309787612400
15. Li, X., S.-X. Gong, L. Yang, and Y.-J. Yang, "A novel Wilkinson power divider for dual-band operation," Journal of Electromagnetic Waves and Applications, Vol. 23, No. 2-3, 395-404, 2009.
doi:10.1163/156939309787604346
16. Wu, L., Z. Sun, H. Yilmaz, and M. Berroth, "A dual-frequency Wilkinson power divider," IEEE Trans. Microwave Theory Tech., Vol. 54, No. 1, 278-284, 2006.
doi:10.1109/TMTT.2005.860300
17. Leung, C. and Q. Xue, "A parallel-strip ring power divider with high isolation and arbitrary power-dividing ratio," IEEE Trans. Microwave Theory Tech., Vol. 55, No. 11, 2419-2426, Nov. 2007.
18. Chiu, L., T. Yum, Q. Xue, and C. Chan, "A wideband compact parallel-strip 180° Wilkinson power divider for push-pull circuitries," IEEE Microw. Wireless Compon. Lett., Vol. 16, No. 1, 49-51, 2006.
doi:10.1109/LMWC.2005.859972
19. Goodman, P. C., "A wideband stripline matched power divider," IEEE MTT-S International Microwave Symposium Digest, Vol. 68, No. 1, 16-20, May 1968.
20. Mencia-Oliva, B., A. M. Pelaez-Perez, P. Almorox-Gonzalez, and J. I. Alonso, "New technique for the design of ultra-broadband power dividers based on tapered lines," IEEE/MTT-S International Microwave Symposium, 493-496, Jun. 2009.
21. Zhuanhong, J., Z. Qinglin, and A. Faliang, "A 2-way broad-band microstrip matched power divider," Proceedings of International Conference on Communications, Circuits and Systems, Vol. 4, 2592-2596, Jun. 2006.
22. Abbosh, A. M., "Ultra wideband in-phase power divider for multilayer technology," IET Microwave, Antenna and Propagation, Vol. 3, No. 1, 148-153, 2009.
doi:10.1049/iet-map:20070310
23. Hecken, R. P., "A near-optimum matching section without discontinuities," IEEE Trans. Microwave Theory Tech., Vol. 20, No. 11, 734-739, Nov. 1972.
doi:10.1109/TMTT.1972.1127862
24. Klopfenstein, R. W., "A transmission line taper of improved design," Proceedings IRE, Vol. 44, 31-35, Jan. 1956.
doi:10.1109/JRPROC.1956.274847