A four-stage switched beam antenna array at millimeter-wave (mm-wave) frequencies is designed, fabricated, and experimental results are demonstrated. A novel rectangular loop dipole antenna (RLDA) applying the quasi Yagi-Uda concept is designed to achieve high gain and wide bandwidth with end-fire radiation. This RLDA with director has a return loss better than 10 dB over a frequency range of 32 GHz to 37 GHz and a peak gain of 8.5 dB. The proposed high gain end-fire RLDA antenna in combination with a 4x4 Butler Matrix(BM) creates the switched beam configuration and generates four beams in the directions of 15˚±2˚, -45˚±4˚, 38˚±2˚, and -15˚±1˚ at 33.5 GHz, 34.5 GHz, and 35.5 GHz with successive input port excitation. The switched beam configuration has overall dimensions at 34.5 GHz is 26 mm x 25.8 mm (3.03λ x 3.0λ).
2. Abumunshar, A. J., K. Sertel, and N. K. Nahar, "Millimeter-wave tightly-coupled phased array with integrated MEMS phase shifters," Progress In Electromagnetics Research C, Vol. 110, 135-150, 2021.
3. Dadgarpour, B. Z., B. S. Virdee, and T. A. Denidni, "Beam tilting antenna using integrated metamaterial loading," IEEE Transactions on Antennas and Propagation, Vol. 62, No. 5, 2874-2879, May 2014, doi: 10.1109/TAP.2014.2308516.
4. Mantash, M., A. Kesavan, and T. A. Denidni, "Beam-tilting endfire antenna using a single-layer FSS for 5G communication networks," IEEE Antennas and Wireless Propagation Letters, Vol. 17, No. 1, 29-33, Jan. 2018, doi: 10.1109/LAWP.2017.2772222.
5. Dale Ake, W., M. Pour, and A. Mehrabani, "Asymmetric half-bowtie antennas with tilted beam patterns," IEEE Transactions on Antennas and Propagation, Vol. 67, No. 2, 738-744, Feb. 2019, doi: 10.1109/TAP.2018.2880078.
6. Mosca, S., F. Bilotti, A. Toscano, and L. Vegni, "A novel design method for Blass matrix beam-forming networks," IEEE Transactions on Antennas and Propagation, Vol. 50, No. 2, 225-232, Feb. 2002, doi: 10.1109/8.997999.
7. Fakoukakis, F. and G. Kyriacou, "Novel nolen matrix based beamforming networks for series-fed low SLL multibeam antennas," Progress In Electromagnetics Research B, Vol. 51, 33-64, 2013.
8. Rahimian, A., Y. Alfadhl, and A. Alomainy, "Design and performance analysis of millimetre-wave Rotman lens-based array beamforming networks for large-scale antenna subsystems," Progress In Electromagnetics Research C, Vol. 78, 159-171, 2017.
9. Lian, J., Y. Ban, Z. Chen, B. Fu, and C. Xiao, "SIW folded Cassegrain lens for millimeter-wave multibeam application," IEEE Antennas and Wireless Propagation Letters, Vol. 7, No. 4, 583-586, Apr. 2018, doi: 10.1109/LAWP.2018.2804923.
10. Butler, J. and R. Lowe, "Beam-forming matrix simplifies design of electronically scanned antennas," Electronic Design, Vol. 9, 170-173, Apr. 12, 1961.
11. Panduro, M. A. and C. del Rio-Bocio, "Simplifying the feeding network for multibeam circular antenna arrays by using corps," Progress In Electromagnetics Research Letters, Vol. 21, 119-128, 2011.
12. Panduro, M. A. and C. del Ro-Bocio, "Design of beam-forming networks using CORPS and evolutionary optimization," International Journal of Electronics and Communications, Vol. 63, No. 5, 353-365, 2009, doi: 10.1016/j.aeue.2008.02.009.
13. Panduro, M. A. and C. del Río-Bocio, "Design of beam-forming networks for scannable multi-beam antenna arrays using CORPS," Progress In Electromagnetics Research, Vol. 84, 173-188, 2008.
14. Juárez, E., M. A. Panduro, A. Reyna, D. H. Covarrubias, A. Mendez, and E. Murillo, "Design of concentric ring antenna arrays based on subarrays to simplify the feeding system," Symmetry, Vol. 12, No. 6, 970, Jun. 2020, https://doi.org/10.3390/sym12060970.
15. Tseng, C., C. Chen, and T. Chu, "A low-cost 60-GHz switched-beam patch antenna array with butler matrix network," IEEE Antennas and Wireless Propagation Letters, Vol. 7, 432-435, 2008, doi: 10.1109/LAWP.2008.2001849.
16. Karamzadeh, S., V. Rafiei, and M. Kartal, "Beam steering fabry perot array antenna for MM-wave application," Progress In Electromagnetics Research M, Vol. 91, 81-89, 2020.
17. Ashraf, N., A.-R. Sebak, and A. A. Kishk, "PMC packaged single-substrate 4 × 4 butler matrix and double-ridge gap waveguide horn antenna array for multibeam applications," IEEE Transactions on Microwave Theory and Techniques, Vol. 69, No. 1, 248-261, Jan. 2021, doi: 10.1109/TMTT.2020.3022092.
18. Trinh-Van, S., J. M. Lee, Y. Yang, K. Lee, and K. C. Hwang, "A sidelobe-reduced, four-beam array antenna fed by a modified 4 × 4 butler matrix for 5G applications," IEEE Transactions on Antennas and Propagation, Vol. 67, No. 7, 4528-4536, Jul. 2019, doi: 10.1109/TAP.2019.2905783.
19. Lian, J., Y. Ban, C. Xiao, and Z. Yu, "Compact substrate-integrated 4 × 8 butler matrix with sidelobe suppression for millimeter-wave multibeam application," IEEE Antennas and Wireless Propagation Letters, Vol. 17, No. 5, 928-932, May 2018, doi: 10.1109/LAWP.2018.2825367.
20. Cao, Y., K. Chin, W. Che, W. Yang, and E. S. Li, "A compact 38 GHz multibeam antenna array with multifolded butler matrix for 5G applications," IEEE Antennas and Wireless Propagation Letters, Vol. 16, 2996-2999, 2017, doi: 10.1109/LAWP.2017.2757045.
21. Balanis, C. A., Antenna Theory --- Analysis and Design, 3rd Ed., John Wiley & Sons, Inc., 2005.