Planar Multibeam Array Antenna with Rotman Lens Beamformer for 5GHz Band Wireless Applications

Document Type : Research Paper


1 Dept. of Electrical & Computer Eng., Isfahan Univ. of Technology, 8415683111

2 Department of Electrical and Computer Engineering, Isfahan University of Technology, Isfahan, Iran


A planar multi-beam array with a co-planar Rotman lens beamformer is introduced for wireless applications. The array consists of 8 linear series-fed subarrays with proximity-coupled patch elements. The Rotman lens feeds the subarrays through coupling slots. To reduce beam squinting, the subarrays are fed from the center. The coupling slot feeds each arm of a subarray 180° out of phase. To compensate out-of phase feeding, two feeding arms of each subarray are designed in the opposite direction. Also, cross-polar radiation is reduced significantly. In order to reduce the size of radiating patches to fit within array cell size, they are formed by four sub-patches with indentions and are fed by microstrip line from feed layer with two matching sections to improve the bandwidth. Measured results of the array structure in terms of the S-parameter of beam ports and radiation patterns are presented.


1- T. Katagi, S. Mano, and S. Sato, "An improved design method of Rotman lens antennas," IEEE Trans. Antennas Propag., vol. 32, no. 5, pp. 524-527, May 1984.
2-  P. K. Singhal, P. C. Sharma, and R. D. Gupta, "Rotman lens with equal height of array and feed contours," IEEE Trans. Antennas Propag., vol. 51, no. 8, pp. 2048-2056, Aug. 2003.
3-  P. S. Hall and S. J. Vetterlein, "Review of radio frequency beamforming techniques for scanned and multiple beam antennas," IEE Proceedings H ( Microwaves, Antennas and Propag., vol. 137, no. 5, pp. 293-303, Oct. 1990.
4- R. Bayderkhani and H. R. Hassani, "Wideband and Low Sidelobe Slot Antenna Fed by Series-Fed Printed Array," IEEE Trans. Antennas Propagation, vol. 58, no. 12, pp. 3898-3904, Dec. 2010.
5- F. Y. Kuo and R. B. Hwang, "High-Isolation X-Band Marine Radar Antenna Design," IEEE Trans. Antennas Propagation, vol. 62, no. 5, pp. 2331-2337, May 2014.
6- D. M. Pozar, D. H. Schaubert, I. Antennas, and P. Society, Microstrip Antennas: The Analysis and Design of Microstrip Antennas and Arrays. Wiley-USA, 1995.
7- K. K. Chan and S. K. Rao, "Design of a Rotman lens feed network to generate a hexagonal lattice of multiple beams," IEEE Trans. Antennas Propagation, vol. 50, no. 8, pp. 1099-1108, Aug. 2002.
8- H.-I. Lin and W.-J. Liao, "A beam switching array based on Rotman lens for MIMO technology," in Microwave and Millimeter Wave Technology (ICMMT), 2012 International Conference on, 2012, vol. 2, pp. 1-4.
9- D. Nussler, R. Brauns, and H.-H. Fuchs, "A two dimensional lens stack design for 94 GHz," in 2009 German Microwave Conference, pp. 1-4.
10- G. Sole and M. Smith, "Multiple beam forming for planar antenna arrays using a three-dimensional Rotman lens," IEE Proceedings H (Microwaves, Antennas and Propag.), vol. 134, no. 4, pp. 375-385, Aug. 1987.
11- Y. Tao and G. Delisle, "Lens-fed multiple beam array for millimeter wave indoor communications," in IEEE Antennas and Propagation Society International Symposium, 1997. Digest, vol. 4, pp. 2206-2209.
12- Y. Liu, H. Yang, D. Huang, and J. Zhu, "A low sidelobe multi-beam slot array antenna fed by rotman lens," in Antennas & Propagation Conference (LAPC), 2016 Loughborough, 2016, pp. 1-5.
13- W. Lee, K. Young Sub, J. Kim, and Y. J. Yoon, "Multi-layer beamforming lens antenna array with a new line design for millimeter-wave system-in-package applications," in Proceedings of the 5th European Conference on Antennas and Propagation (EUCAP), 2011, pp. 2954-2958.
14- S. Peik and J. Heinstadt, "Multiple beam microstrip array fed by Rotman lens," in Antennas and Propagation, 1995., Ninth International Conference on (Conf. Publ. No. 407), 1995, vol. 1, pp. 348-351.
15- S. Park, Y. Tsunemitsu, J. Hirokawa, and M. Ando, "Center feed single layer slotted waveguide array," IEEE Trans. Antennas Propagation, vol. 54, no. 5, pp. 1474-1480, May 2006.
16- A. Bisognin et al., "A new symmetric feeding technique for a broadband series-fed antenna-array," in Antennas and Propagation Society International Symposium (APSURSI), 2013 IEEE, 2013, pp. 2183-2184.
17- Z. Tao, J. Zhu, T. Zuo, L. Pan, and Y. Yu, "Broadband microstrip-to-microstrip vertical transition design," IEEE Microwave and Wireless Components Letters, vol. 26, no. 9, pp. 660-662, Sept. 2016.
18- S. A. Wartenberg and Q. H. Liu, "A coaxial-to-microstrip transition for multi-layer substrates," IEEE Trans. Microw. Theory Tech., vol. 52, no. 2, pp. 584-588, Feb. 2004.
19- A. Abbosh, "Ultra wideband vertical microstrip–microstrip transition," IET Microwaves, Antennas & Propagation, vol. 1, no. 5, pp. 968-972, 2007.
20- F. P. Casares-Miranda, C. Viereck, C. Camacho-Peñalosa, and C. Caloz, "Vertical microstrip transition for multi-layer microwave circuits with decoupled passive and active layers," IEEE Microwave and Wireless Components Letters, vol. 16, no. 7, pp. 401-403, July 2006.
21- W. Rotman and R. Turner, "Wide-angle microwave lens for line source applications," IEEE Trans. Antennas Propag., vol. 11, no. 6, pp. 623-632, Nov. 1963.
22- P. K. Singhal, R. D. Gupta, and P. C. Sharma, "Recent trends in design and analysis of Rotman-type lens for multiple beamforming," International Journal of RF and Microwave Computer-Aided Engineering, vol. 8, no. 4, pp. 321-338, 1998.
23- J. Dong and A. I. Zaghloul, "Hybrid Ray Tracing Method for Microwave Lens Simulation," IEEE Trans. Antennas Propag., vol. 59, no. 10, pp. 3786-3796, Oct. 2011.
24- E. O. Rausch and A. F. Peterson, "Rotman lens design issues," in Antennas and Propagation Society International Symposium, 2005 IEEE, vol. 2, pp. 35-38.