This paper presents the analytical design and numerical performance evaluation of novel V-band millimetre-wave (mm-wave) beamforming networks (BFNs), based on the Rotman lens array feeding concept. The devices are intended for operation in the unlicensed 60-GHz frequency band. The primary objective of this work is to study the feasibility of designing flexible V-band beamformers, based on liquid-crystal polymer (LCP) substrates. The planar Rotman lens device has been initially developed, and the output performances, in terms of the scattering parameters and accuracy, have been analysed. This is further continued with the detailed designs of the Rotman lens BFNs based on the four different proposed flexural cases, namely the concave-axial bending, the convex-axial bending, the concave-circumferential bending, and the convex-circumferential bending. Each of the flexures has been analysed, and the performance in terms of the surface currents and phase distributions, as the primary functionality indicators, has been presented. The presented flexible beamformers exhibit significant characteristics to be potentially employed as low-cost and efficient units of the mm-wave transceivers with the in-built beam steering capabilities for the conformal wireless subsystems.
2. Haghzadeh, M., H. M. Jaradat, C. Armiento, and A. Akyurtlu, "Design and simulation of fully printable conformal antennas with BST/polymer composite based phase shifters," Progress In Electromagnetics Research C, Vol. 62, 167-178, 2016.
3. Elias, N. A., et al., "Bending and crumpling deformation study of the resonant characteristic and SAR for a 2.4 GHz textile antenna," Jurnal Teknologi, Vol. 77, No. 10, 17-23, 2015.
4. Tang, M.-C., T. Shi, and R. W. Ziolkowski, "Flexible efficient quasi-Yagi printed uniplanar antenna," IEEE Transactions on Antennas and Propagation, Vol. 63, No. 12, 5343-5350, Dec. 2015.
5. Fan, K. K. and Z.-C. Hao, "\Cylindrical conformal array antenna with tilted H-plane Fan-shaped beam for millimeter-wave application," Microwave and Optical Technology Letters, Vol. 58, No. 7, 1666-1671, Jul. 2016.
6. Semkin, V., et al., "Beam switching conformal antenna array for mm-wave communications," IEEE Antennas and Wireless Propagation Letters, Vol. 15, 28-31, Feb. 2016.
7. Saeed, S. M., C. A. Balanis, and C. R. Birtcher, "Inkjet-printed flexible reconfigurable antenna for conformal WLAN/WiMAX wireless devices," IEEE Antennas and Wireless Propagation Letters, 2016.
8. Hur, S., et al., "Millimeter wave beamforming for wireless backhaul and access in small cell networks," IEEE Transactions on Communications, Vol. 61, No. 10, 4391-4403, Oct. 2013.
9. Rappaport, T. S., et al., "Millimeter wave mobile communications for 5G cellular: It will work!," IEEE Access, Vol. 1, 335-349, May 2013.
10. Niu, Y., et al., "A survey of millimeter wave communications (mm Wave) for 5G: Opportunities and challenges," Wireless Networks, Vol. 21, No. 8, 2657-2676, Nov. 2015.
11. Zhu, Y., et al., "Demystifying 60 GHz outdoor picocells," 20th Annual International Conference on Mobile Computing and Networking (MobiCom), 5-16, Sep. 2014.
12. Verma, L., M. Fakharzadeh, and S. Choi, "Backhaul need for speed: 60 GHz is the solution," IEEE Wireless Communications, Vol. 22, No. 6, 114-121, Dec. 2015.
13. 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.
14. 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, Third Quarter, 2016.
15. 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.
16. 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.
17. Singhal, P. K, 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. 3, 321-338, Feb. 1998.
18. Simon, P. S., "Analysis and synthesis of Rotman lenses," 22nd AIAA International Communications Satellite Systems Conference & Exhibit, 1-11, May 2004.
19. Vashist, S., M. K. Soni, and P. K. Singhal, "A review on the development of Rotman lens antenna," Chinese Journal of Engineering, Vol. 2014, article ID 385385, 1-9, Jul. 2014.
20. Rahim, S. K. A. and P. Gardner, "A novel active antenna beamforming networks using Butler matrices," Progress In Electromagnetics Research C, Vol. 11, 183-198, 2009.
21. Song, I. S., et al., "60 GHz Rotman lens and new compact low loss delay line using LTCC technology," IEEE Radio and Wireless Symposium (RWS), 663-666, Jan. 2009.
22. Lee, W., et al., "Compact two-layer Rotman lens-fed microstrip antenna array at 24 GHz," IEEE Transactions on Antennas and Propagation, Vol. 59, No. 2, 460-466, Feb. 2011.
23. 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.
24. 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.
25. 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.
26. 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.
27. Bhattacharyya, A. K., Phased Array Antennas: Floquet Analysis, Synthesis, BFNs and Active Array Systems, John Wiley & Sons, 2006.
28. Cho, C.-L., et al., "Inkjet-printed multilayer bandpass filter using liquid crystal polymer system-on-package technology," IEEE Transactions on Components, Packaging and Manufacturing Technology, Vol. 6, No. 4, 622-629, Apr. 2016.
29. Cabrol, P. and P. Pietraski, "60 GHz patch antenna array on low cost liquid-crystal polymer (LCP) substrate," IEEE Long Island Systems, Applications and Technology Conference (LISAT), 1-6, May 2014.
30. Liu, D. and Y. P. Zhang, "Integration of array antennas in chip package for 60-GHz radios," Proceedings of the IEEE, Vol. 100, No. 7, 2364-2371, Jul. 2012.
31. Saily, J., et al., "Millimetre-wave beam-switching Rotman lens antenna designs on multi-layered LCP substrates," 10th European Conference on Antennas and Propagation (EuCAP), 1-5, Apr. 2016.
32. Kingsley, N., G. E. Ponchak, and J. Papapolymerou, "Reconfigurable RF MEMS phased array antenna integrated within a liquid crystal polymer (LCP) system-on-package," IEEE Transactions on Antennas and Propagation, Vol. 56, No. 1, 108-118, Jan. 2008.
33. Lamminen, A., et al., "Dual-circular polarised patch antenna array on LCP for 60 GHz millimetre-wave identification," 8th European Conference on Antennas and Propagation (EuCAP), 537-541, Apr. 2014.
34. Thompson, D. C., et al., "Characterization of liquid crystal polymer (LCP) material and transmission lines on LCP substrates from 30 to 110 GHz," IEEE Transactions on Microwave Theory and Techniques, Vol. 52, No. 4, 1343-1352, Apr. 2004.
35. Christie, S., et al., "Rotman lens-based retrodirective array," IEEE Transactions on Antennas and Propagation, Vol. 60, No. 3, 1343-1351, Mar. 2012.
36. Rotman, R., M. Tur, and L. Yaron, "True time delay in phased arrays," Proceedings of the IEEE, Vol. 104, No. 3, 504-518, Mar. 2016.
37. Kutty, S. and D. Sen, "Beamforming for millimeter wave communications: An inclusive survey," IEEE Communications Surveys & Tutorials, Vol. 18, No. 2, 949-973, Second Quarter, 2016.
38. Soh, P. J. and G. A. E. Vandenbosch, "Textile antennas for body area networks: design strategies and evaluation methods," Electromagnetics of Body Area Networks: Antennas, Propagation, and RF Systems, D. H. Werner and Z. H. Jiang, Eds., 1-25, John Wiley & Sons, Inc., 2016.