A compact planar 4 x 4 microstrip Butler matrix is proposed in this paper. It is a wideband beam-forming network with the advantages of compact size, low cost and ease of fabrication. Three-branch line couplers with lumped-distributed elements are adopted to reduce the size, and multi-U-shaped coupled-line Schiffman phase shifters are designed to get good transmission and phase performances. The Butler matrix is fabricated and measured, and a good agreement is found between the simulated and measured results, which makes it very attractive for wideband multi-beam antenna applications.
2. Nedil, M., T. A. Denidni, and L. Talbi, "Novel Butler matrix using CPW multilayer technology," IEEE Trans. Microw. Theory Tech., Vol. 54, No. 1, 499-507, 2006.
3. Gruszczynski, S. and K. Wincza, "Broadband 4x4 Butler matrices as a connection of symmetrical multisection coupled-line 3-dB directional couplers and phase correction networks," IEEE Trans. Microw. Theory Tech., Vol. 57, No. 1, 1-9, 2009.
4. Djerafi, T., N. J. G. Fonseca, and K. Wu, "Design and implementation of a planar 4x4 Butler matrix in SIW technology for wideband applications," Proceedings of the 40th European Microwave Conference, 910-913, 2010.
5. Zheng, S., W. S. Chan, S. H. Leung, and Q. Xue, "Broadband Butler matrix with flat coupling," Electr. Lett., Vol. 43, No. 10, 576-577, 2007.
6. He, J., B. Z. Wang, Q. Q. He, Y. X. Xing, and Z. L. Yin, "Wideband X-band microstrip Butler matrix," Progress In Electromagnetics Research, Vol. 74, 131-140, 2007.
7. Vogel, R. W., "Analysis and design of lumped- and lumped-distributed element directional couplers for MIC and MMIC applications," IEEE Trans. Microw. Theory Tech., Vol. 40, No. 2, 253-262, 1992.
8. Chun, Y. H. and J. S. Hong, "Design of a compact broad-band branchline hybrid," IEEE MTT-S Int. Microw. Symp. Dig., 997-1000, Long Beach, CA, 2005.
9. Chun, Y. H. and J. S. Hong, "Compact wide-band branch-line hybrids," IEEE Trans. Microw. Theory Tech., Vol. 54, No. 2, 704-709, 2006.
10. Schiffman, B. M., "A new class of broad-band microwave 90-degree phase shifters," IRE Trans. Microw. Theory Tech., 232-237, 1958.
11. Quirartc, J. L. R. and J. P. Starski, "Synthesis of Schiffman phase shifters," IEEE Trans. Microw. Theory Tech., Vol. 39, No. 11, 1885-1889, 1991.
12. Muracuchi, M., T. Yukitake, and Y. Naito, "Optimum design of 3-dB branch-line couplers using microstrip lines," IEEE Trans. Microw. Theory Tech., Vol. 31, No. 8, 674-678, 1983.
13. Jafari, E., F. Hodjatkashani, and R. Rezaiesarlak, "A broadband quadrature hybrid using improved wideband Schiffman phase shifter," Progress In Electromagnetics Research C, Vol. 11, 229-236, 2009.
14. Zhang, Z., Y. C. Jiao, S. F. Cao, X. M. Wang, and F. S. Zhang, "Modified broadband Schiffman phase shifter using dentate microstrip and patterned ground plane," Progress In Electromagnetics Research Letters, Vol. 24, 9-16, 2011.