Liquid-Crystal-Based Beam Steerable Planar Antennas for 60 GHz Wireless Networks

The huge bandwidth available in the unlicensed 57-66 GHz spectrum can support multi-gigabit transmission. Depending on the operating environment and application, 60 GHz wireless networks with ranges between 10 m to 100 m are attractive and currently are under research and development. They can have immense applications in consumer and professional electronic markets. Not only do wireless networks eliminate cabling between communicating terminals, but they permit high definition (HD) uncompressed video streaming over air, can support wireless HD video interactive games, allow secure multi-gigabit data link between close city offices, and can provide safe and fast data, audio and video wireless distribution in planes, trains, cars, offices, hospitals and many other places of interests. Restricted to these applications alone, the sale of 60 GHz chipsets is estimated to run into billion of units. In the 60 GHz band the external interference is extremely low as the absorption of electromagnetic signals by oxygen and obstacles are extremely high. Unfortunately, the high attenuation together with the low transmitter power adversely affects the transmission quality. As flagged by the industry, this problem can be overcome by the implementation of directional antennas in 60 GHz transceivers, capable of steering their beams automatically for maximum signal reception. The aim of this work is to develop beam steerable planar antenna arrays for the 60 GHz band using nematic liquid crystals as a means for controlling the phase distribution over the antenna elements and hence, to provide prototype antennas which are compact, low-power and low-cost for multi-gigabit 60 GHz wireless networks. For this purpose, we will investigate, develop and compare two types of phase shifters based on liquid crystals, and design and build beam steering antenna arrays integrating the best alternative. Both the optimisation of the phase shifter performance and the development of the antenna arrays require detailed liquid crystal and electromagnetic modelling for which there is no commercial software available. In this work, our own advanced liquid crystal and electromagnetic modelling methods are extended and software tools capable of dealing with fully inhomogeneous and anisotropic dielectrics (on a point by point basis) will be developed in order to analyse and design accurately and reliably the 2D and 3D liquid-crystal-based devices including phase shifters and antennas.

The economic benefit of the research will be primarily in the telecommunication sector involved in the development of 60 GHz networks. The demand for 60 GHz chipsets alone is estimated to be of over a billion units for consumer and professional markets and phase shifters and beam formers will be essential for their use. The UK communication industry has an outstanding record in the development and exploitation with a 52 billion a year market in 2008 (Lord Carter's report). There are many companies who would have interests in the final antenna prototypes arising from the proposed research. In addition to the telecommunication sector, the mm-wave imaging industry including those making body scanners/cameras for security systems in airports would benefit from the research results on the liquid-crystal-based phase shifters for control or formation of beams from mm-wave phased array antennas integrated with the phase shifters. Other possible beneficiaries are the radar industry, involved in the development of car radars, robotic cars and short range radars as aircraft landing aid. Manufacturers of liquid crystal materials and researchers will benefit from this research as we intend to characterise and compare their products and study their suitability for RF applications. In addition, since the proposed work eliminates cables or fibres to set-up ultra wideband data networks, its results should have positive impacts on environment, energy consumption for cable manufacturing, and infra-structure planning. Already such benefits are strongly associated with cellular mobile communications, especially in those disadvantaged areas where there is no cable networks for normal telephony communication.