1. Kutty, S. and D. Sen, "Beamforming for millimeter wave communications: An inclusive survey," IEEE Communications Surveys & Tutorials, Vol. 18, No. 2, 949-973, 2016.
doi:10.1109/COMST.2015.2504600

2. Pang, X., W. Hong, T. Yang, and L. Li, "Design and implementation of an active multibeam antenna system with 64 RF channels and 256 antenna elements for massive MIMO application in 5G wireless communications," China Communications, Vol. 11, No. 11, 16-23, Nov. 2014.

3. Yuan, H.-W., G.-F. Cui, and J. Fan, "A method for analyzing broadcast beamforming of massive MIMO antenna array," Progress In Electromagnetics Research Letters, Vol. 65, 15-21, 2017.
doi:10.2528/PIERL16063005

4. Agiwal, M., A. Roy, and N. Saxena, "Next generation 5G wireless networks: A comprehensive survey," IEEE Communications Surveys & Tutorials, Vol. 18, No. 3, 1617-1655, 2016.
doi:10.1109/COMST.2016.2532458

5. Ala-Laurinaho, J., et al. "2-D beam-steerable integrated lens antenna system for 5G E-band access and backhaul," IEEE Transactions on Microwave Theory and Techniques, Vol. 64, No. 7, 2244-2255, Jul. 2016.
doi:10.1109/TMTT.2016.2574317

6. Uchendu, I. and J. Kelly, "Survey of beam steering techniques available for millimeter wave applications," Progress In Electromagnetics Research B, Vol. 68, 35-54, 2016.
doi:10.2528/PIERB16030703

7. Rahimian, A. and F. Mehran, "RF link budget analysis in urban propagation microcell environment for mobile radio communication systems link planning," International Conference on Wireless Communications and Signal Processing (WCSP), 1-5, Nov. 2011.

8. Venkateswaran, V., F. Pivit, and L. Guan, "Hybrid RF and digital beamformer for cellular networks: Algorithms, microwave architectures, and measurements," IEEE Transactions on Microwave Theory and Techniques, Vol. 64, No. 7, 2226-2243, Jul. 2016.
doi:10.1109/TMTT.2016.2569583

9. Gao, Y., M. Khaliel, and T. Kaiser, "Wideband hybrid analog-digital beamforming massive MIMO systems based on Rotman lens," IEEE International Conference on Communication Systems (ICCS), 1-6, Dec. 2016.

10. Jang, J., et al. "Smart small cell with hybrid beamforming for 5G: Theoretical feasibility and prototype results," IEEE Wireless Communications, Vol. 23, No. 6, 124-131, Dec. 2016.
doi:10.1109/MWC.2016.1500387WC

11. Payami, S., M. Ghoraishi, and M. Dianati, "Hybrid beamforming for large antenna arrays with phase shifter selection," IEEE Transactions on Wireless Communications, Vol. 15, No. 11, 7258-7271, Nov. 2016.
doi:10.1109/TWC.2016.2599526

12. Hall, P. S. and S. J. Vetterlein, "Review of radio frequency beamforming techniques for scanned and multiple beam antennas," IEE Microwaves, Antennas and Propagation, Vol. 137, No. 5, 293-303, Oct. 1990.
doi:10.1049/ip-h-2.1990.0055

13. Fonseca, N. J. G., A. Ali, and H. Aubert, "Cancellation of beam squint with frequency in serial beamforming network-fed linear array antennas," IEEE Antennas and Propagation Magazine, Vol. 54, No. 1, 32-39, Feb. 2012.
doi:10.1109/MAP.2012.6202510

14. Rahimian, A., "Investigation of Nolen matrix beamformer usability for capacity analysis in wireless MIMO systems," 19th Asia-Pacific Conference on Communications (APCC), 622-623, Aug. 2013.
doi:10.1109/APCC.2013.6766023

15. Patterson, C. E., et al. "A 60-GHz active receiving switched-beam antenna array with integrated Butler matrix and GaAs amplifiers," IEEE Transactions on Microwave Theory and Techniques, Vol. 60, No. 11, 3599-3607, Nov. 2012.
doi:10.1109/TMTT.2012.2213834

16. Panduro, M. A. and C. del Rio-Bocio, "Design of beam-forming networks for scannable multi-beam antenna arrays using CORPS," Progress In Electromagnetics Research, Vol. 84, 173-188, 2008.
doi:10.2528/PIER08070403

17. Chan, K. K. and S. K. Rao, "Design of a Rotman lens feed network to generate a hexagonal lattice of multiple beams," IEEE Transactions on Antennas and Propagation, Vol. 50, No. 8, 1099-1108, Aug. 2002.
doi:10.1109/TAP.2002.801292

18. Kushwah, R. P. S., P. K. Singhal, and P. C. Sharma, "Design of symmetric bootlace lens with gain analysis at UHF band," Progress In Electromagnetics Research Letters, Vol. 6, 83-89, 2009.
doi:10.2528/PIERL08122905

19. Lee, W., et al. "Beamforming lens antenna on a high resistivity silicon wafer for 60 GHz WPAN," IEEE Transactions on Antennas and Propagation, Vol. 58, No. 3, 706-713, Mar. 2010.
doi:10.1109/TAP.2009.2039331

20. Lee, W., et al. "Compact two-layer Rotman lens-fed microstrip antenna array at 24GHz," IEEE Transactions on Antennas and Propagation, Vol. 59, No. 2, 460-466, Feb. 2011.
doi:10.1109/TAP.2010.2096380

21. Rahimian, A., "Microwave beamforming networks employing Rotman lenses and cascaded Butler matrices for automotive communications beam scanning electronically steered arrays," Microwaves, Radar and Remote Sensing Symposium (MRRS), 351-354, Aug. 2011.
doi:10.1109/MRRS.2011.6053671

22. Rotman, W. and R. F. Turner, "Wide-angle microwave lens for line source applications," IEEE Transactions on Antennas and Propagation, Vol. 11, No. 6, 623-632, Nov. 1963.
doi:10.1109/TAP.1963.1138114

23. Peterson, A. F. and E. O. Rausch, "Scattering matrix integral equation analysis for the design of a waveguide Rotman lens," IEEE Transactions on Antennas and Propagation, Vol. 47, No. 5, 870-878, May 1999.
doi:10.1109/8.774150

24. Katagi, T., S. Mano, and S. Sato, "An improved design method of Rotman lens antennas," IEEE Transactions on Antennas and Propagation, Vol. 32, No. 5, 524-527, May 1984.
doi:10.1109/TAP.1984.1143353

25. Hansen, R. C., "Design trades for Rotman lenses," IEEE Transactions on Antennas and Propagation, Vol. 39, No. 4, 464-472, Apr. 1991.
doi:10.1109/8.81458

26. Singhal, P. K., P. C. Sharma, and R. D. Gupta, "Rotman lens with equal height of array and feed contours," IEEE Transactions on Antennas and Propagation, Vol. 51, No. 8, 2048-2056, Aug. 2003.
doi:10.1109/TAP.2003.814742

27. Simon, P. S., "Analysis and synthesis of Rotman lenses," 22nd AIAA International Communications Satellite Systems Conference & Exhibit, 1-11, May 2004.

28. Cheng, Y. J., et al. "Substrate integrated waveguide (SIW) Rotman lens and its Ka-band multibeam array antenna applications," IEEE Transactions on Antennas and Propagation, Vol. 56, No. 8, 2504-2513, Aug. 2008.
doi:10.1109/TAP.2008.927567

29. Vashist, S., M. K. Soni, and P. K. Singhal, "A review on the development of Rotman lens antenna," Chinese Journal of Engineering, Vol. 2014, 1-9, article ID: 385385, Jul. 2014.

30. Christie, S., et al. "Rotman lens-based retrodirective array," IEEE Transactions on Antennas and Propagation, Vol. 60, No. 3, 1343-1351, Mar. 2012.
doi:10.1109/TAP.2011.2180347

31. Tekkouk, K., M. Ettorre, L. Le Coq, and R. Sauleau, "Multibeam SIW slotted waveguide antenna system fed by a compact dual-layer Rotman lens," IEEE Transactions on Antennas and Propagation, Vol. 64, No. 2, 504-514, Feb. 2016.
doi:10.1109/TAP.2015.2499752

32. Attaran, A., R. Rashidzadeh, and A. Kouki, "60GHz low phase error Rotman lens combined with wideband microstrip antenna array using LTCC technology," IEEE Transactions on Antennas and Propagation, Vol. 64, No. 12, 5172-5180, Dec. 2016.
doi:10.1109/TAP.2016.2618479

33. Wang, Z., B. Xiang, and F. Yang, "A multibeam antenna array based on printed Rotman lens," International Journal of Antennas and Propagation, 1-6, article ID: 179327, 2013.

34. Rahimian, A., "Design and performance of a Ku-band Rotman lens beamforming network for satellite systems," Progress In Electromagnetics Research M, Vol. 28, 41-55, 2013.
doi:10.2528/PIERM12111511

35. Rajabalian, M. and B. Zakeri, "Optimisation and implementation for a non-focal Rotman lens design," IET Microwaves, Antennas & Propagation, Vol. 9, No. 9, 982-987, Jun. 2015.
doi:10.1049/iet-map.2014.0797

36. Dong, J. and A. I. Zaghloul, "Extremely high-frequency beam steerable lens-fed antenna for vehicular sensor applications," IET Microwaves, Antennas & Propagation, Vol. 4, No. 10, 1549-1558, Oct. 2010.
doi:10.1049/iet-map.2009.0271

37. Saily, J., et al. "Millimetre-wave beam-switching Rotman lens antenna designs on multilayered LCP substrates," 10th European Conference on Antennas and Propagation (EuCAP), 1-5, Apr. 2016.

38. Lamminen, A., et al. "Gain enhanced millimetre-wave beam-switching Rotman lens antenna designs on LCP," 11th European Conference on Antennas and Propagation (EuCAP), 2781-2785, Mar. 2017.

39. Jilani, S. F., B. Greinke, Y. Hao, and A. Alomainy, "Flexible millimetre-wave frequency reconfigurable antenna for wearable applications in 5G networks," URSI International Symposium on Electromagnetic Theory (EMTS), 846-848, Aug. 2016.
doi:10.1109/URSI-EMTS.2016.7571536

40. Rahimian, A., Y. Alfadhl, and A. Alomainy, "Analytical and numerical evaluations of flexible Vband Rotman lens beamforming network performance for conformal wireless subsystems," Progress In Electromagnetics Research B, Vol. 71, 77-89, 2016.
doi:10.2528/PIERB16082605

41. Vo Dai, T. K. and O. Kilic, "Compact Rotman lens structure configurations to support millimeter wave devices," Progress In Electromagnetics Research B, Vol. 71, 91-106, 2016.
doi:10.2528/PIERB16082704

42. Clemens, M. and T. Weiland, "Discrete electromagnetism with the finite integration technique," Progress In Electromagnetics Research, Vol. 32, 65-87, 2001.
doi:10.2528/PIER00080103

43. Weiland, T., M. Timm, and I. Munteanu, "A practical guide to 3-D simulation," IEEE Microwave Magazine, Vol. 9, No. 6, 62-75, Dec. 2008.
doi:10.1109/MMM.2008.929772

44. Attaran, A. and S. Chowdhury, "Fabrication of a 77 GHz Rotman lens on a high resistivity silicon wafer using lift-off process," International Journal of Antennas and Propagation, 1-9, article ID: 471935, 2014.