Liquid Antennas

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The antenna, as an essential device for radio systems and "Internet of Things", is in high demand in a wide range of wireless products. It has traditionally been made of good conductive materials (such as copper) to minimise the ohmic loss and maximise the radiation efficiency. However conductive/metal antennas are not ideal for some applications. For example, at lower frequencies, they are normally large, heavy and expensive. They also produce relatively large radar cross sections which are not good for military applications. Furthermore, they are solid - once the antennas are made, it is hard to make them reconfigurable and flexible in terms of the electromagnetic performance and mechanical configurations. Recently, water antennas have been studied and found that they could overcome many problems facing the traditional metal antennas and offer some attractive and unique features, such as small in size, cost effective, transparent, flexible and reconfigurable. However, they cannot work at low temperatures (e.g. below 0 degree C) and may suffer from low radiation efficiency and low power handling capacity problems, which make them not suitable for practical applications. Thus, better alternatives to water and conventional metal antennas are required for a wide range of real world applications.In this project, we are going to develop a new type of antenna: liquid antennas, which will offer all the advantages but overcome the problems that water antennas have. The main challenges are1) How to identify the most suitable liquid materials with low loss, thermal and mechanical stability which will work over the desired temperature range (from -30 to +60 degree C), frequency range (from kHz to GHz), and RF/microwave power range (up to kW).2) How to design and make compact and efficient liquid antennas which are flexible or reconfigurable in terms of the main antenna parameters (such as the operational frequency, radiation pattern, and size) and suitable for real world applications. This is an interdisciplinary project which requires expertise from radio frequency (RF) and microwave engineering, chemical and material science. It consists of both theoretical and experimental work. A wide range of liquid materials (not limited to water and sea water) will be studied, especially ionic liquids and antifreezes. Their electromagnetic, thermal and mechanical properties will be screened against temperature, frequency and RF/microwave power levels with the ultimate goal being to make reconfigurable, small liquid antennas to work efficiently and effectively over a wide temperature, frequency and power range. In addition, the reconfigurable techniques suitable for liquid antennas will also be studied thoroughly and two reconfigurable liquid antennas will be developed, optimised to demonstrate their excellent potential features for both military and commercial applications. The work will be undertaken in collaboration with industrial leaders (BAE Systems and Huawei) and academic expert (Prof Luk from Hong Kong) to ensure that this research will bring new knowledge into material science and radio engineering, a novel type of antenna will be introduced to meet the demands from the industry and provide an alternative compact reconfigurable and/or flexible device to the wireless world. The research outcomes of this study (e.g. the liquid and reconfigurable technology) could be extended to other RF and microwave devices (such as filters, delay lines and phase shifters) where low-loss dielectric materials may be used.