Liquid Antennas

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 are
1) 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.

The proposal is about the development of a new type of antenna, liquid antennas, which are very different from the conventional ones. The research outcome will lead to the creation of new knowledge and better understanding of liquid materials, their thermal and electromagnetic properties, and their applications in antennas (and radio systems in general) which will provide an attractive and novel alternative for us to make antennas and radio systems. There is no doubt that this will make a major contribution to the UK's world research standing in antennas, radio communications and material science. This kind of research project will have a long term impact on knowledge, economy, people and society as summarised in our Pathways to Impact. In particular, it will have a major impact on the following sectors:

1) Industry
The direct beneficiaries are the companies directly involved in the project (BAE Systems and Huawei) and the companies making antennas and radio systems who can use the research outcome to introduce new products or improve their products and services. Radio systems are now everywhere to provide connectivities to people and machines, and have become a very important part of the world economy. New RF/microwave systems and devices are emerging all the time. The liquid antennas are not limited to commercial products, but also suitable for many military applications due to their special features such as small size, flexibility, reconfigurability and transparency.

2) Academia
The proposed project is to develop a new type of antenna which is designed to work under various harsh conditions: from -30 degree C and +60 degree C, and over a very large frequency band. How to make use of the liquid features to make reconfigurable antennas is a very challenging task. Furthermore, the power handling capacity will also be studied in this project. Thus a range of liquid materials will be synthesised and studied from a very special angle. This inter-disciplinary research will provide a new opportunity for people from very different areas to work together to produce cutting-edge new knowledge, results and products, benefiting the wider academic community ranging from chemistry through materials to radio frequency/microwave engineering.

3) The Public
The general public and communication service subscribers will benefit from the use of new/improved radio systems, broadband multimedia services with enhanced efficiency, speed, range, performance and sustainability. Since the liquid antennas will be much cheaper than metal antennas, and will also be made of environmental friendly material. Thus the public will also enjoy the cost and environmental benefits.

To disseminate the results, we will publish the work and findings at major international conferences (5 conferences have been planned) and in high-impact peer-reviewed journals (e.g. Nature, Science, IEEE Trans and letters) and open-access publications. We will also disseminate our results through publications that are aimed at the general public through websites and newspaper articles. There will be a dedicated website for this project, to publicise the project activities and research findings in a direct and timely fashion. Any significant outcome will also be publicised through the University PR Office, national and international media. We will seek to patent our discoveries through the Liverpool University Business Gateway and maximise the impact through other channels as identified in our Pathways to Impact.