Millimeter-wave Antennas and Components for Future Mobile Broadband Networks (MILLIBAN)

Lead Research Organisation: Queen Mary, University of London
Department Name: Sch of Electronic Eng & Computer Science

Abstract

Future mobile communication services will require exceptionally high data rates (over 10Gbits/s) to support more demanding user requirements, including High Definition video streaming. True mobile broadband is a major challenge for the telecommunications industry and urgently calls for radical new design approaches. The millimeter wave (mmWave) band (30GHz-300GHz), offers underexploited opportunities in terms of wide available bandwidths thus supporting high data throughput (e.g. multi-Gbps/Tbps) as well as enhanced data security. This is in sharp contrast to the dearth of spectrum in the congested sub-6GHz bands. In recent years there has been considerable interest in using mmWave technology in telecommunication applications.

High performance cost-effective antennas with the ability to focus their radiated energy towards different directions are a crucial requirement for the successful deployment of envisaged mmWave mobile wireless networks. State-of-the-art mmWave antenna technology is unable to support this type of continuous beam steering with low power requirements and wide angular steering range. This imposes a major barrier to the successful development of the envisaged mmWave mobile networks.

The interdisciplinary research described in this proposal will address this major problem. We will develop new paradigms in antenna design leading to breakthroughs in the analogue beamforming performance. This will be based on innovative enabling material technology along with state of the art microfabrication processes building on heritage at the applicants' institutions. The capabilities of the proposed antenna designs will be fully leveraged to maximize the system throughput with the optimized design of mmWave based small cell access techniques and realistic test-bed measurements which will demonstrate opportunities for significantly enhanced communication system throughput.

The outcomes of this work would place the UK at the centre of developments in this transformative area. This joint proposal brings together two globally leading academic research institutes/centres having complementary experimental infrastructure and skills. Importantly, the proposal involves several key industrial partners who will help to shape the programme and shorten the lag between fundamental research and product development thus further increasing impact generation.

Publications

10 25 50

Related Projects

Project Reference Relationship Related To Start End Award Value
EP/P008402/1 23/03/2017 25/10/2018 £673,436
EP/P008402/2 Transfer EP/P008402/1 26/01/2019 04/12/2020 £371,516
 
Description A high gain antenna is analogous to a spot light; in that it sends most of its energy towards a certain direction and relatively little energy in all other directions. One of the most popular forms of high gain antenna is the phased array. This type of antenna consists of a number of radiating elements. Each element generates a, so called, element factor. The configuration and feeding of these elements gives rise to the, so called, array factor. When all of the elements are fed at once, the antenna is able to produce a beam of energy, which is known as the main lobe. Importantly, by changing the excitation applied to the elements it is also possible to electronically steer the main lobe.

In this project we have acquired a deeper knowledge of a novel phased array steering technique, reported earlier in the literature. This steering technique involves dynamically reconfiguring the element factor in conjunction with the array factor. The additional insight discovered is that, when this approach is used: 1) the curve of antenna gain (i.e. sharpness of the main lobe) verses steering angle exhibits a maximum at the angle to which the element factor is steered, 2) the lobe level (i.e. undesirable peaks of radiation occurring in unwanted directions), at wide steering angles, is reduced in comparison with that for a conventional phased array, 3) item 2 increases the maximum steering angle that can be achieved for a given number of radiating elements.

Phased array antennas must incorporate components, known as phase shifters, to control the excitation signal applied to each element. Conventional phase shifters exhibit high insertion loss (i.e. loss of RF/microwave signal power). We have devised, designed, and simulated a novel phase shifter operating at 10GHz. The phase shifter has a wide tuning range and provides extremely low levels of insertion loss compared with conventional technology. This work could have commercial applications and it is something we intend to work on further.

There is considerable interest in reconfigurable antennas which can be used in a wide range of applications wherever antennas need to adapt to their environment. There are 3 main techniques for reconfiguring circuits/antennas: 1) switches/tuning elements, 2) mechanical movement, 3) tunable materials that can vary their bulk properties. The most popular technique for reconfiguring circuits/antennas is to use semiconductor switches/tuning elements and this technology is quite mature. However, it suffers from several important limitations including: (i) significant overall power consumption; (ii) poor harmonic performance; (iii) limited tuning range; (iv) spurious effects due to isolated areas of metalisation; and (v) poor power handling capability. Liquid metals based on alloys of Gallium have the potential to address these limitations. We have begun experimenting with using liquid metal within antennas operating at millimetre wave frequencies. This work requires moving tiny volumes of liquid metal in a very precise way. To enable this and to address other fundamental problems with the technology we now realise that a co-design approach is required involving input from an interdisciplinary team including experts with a background in: chemistry, RF, physics, mechanics, controls, etc.

We have also shown that a phased array can be used as the feed beneath a series of lenses. The lenses are arranged on a circular arc. At wider steering angles several cascaded lenses are used in order to enhance the gain and thus mitigate for scan loss. The approach yields a reduction in scan loss (i.e. the reduction in gain as a beam is steered from the minimum to maximum angle). However, the lobe level was increased partly because the lens provides gain at all angles, around the phased array, not just the angle corresponding to the main beam. Matching layer material was used ensure that the electromagnetic waves, launched from the phased array, were properly absorbed by the lenses rather than simply being reflected off the surface of the lenses. We discovered that it is very important to use low loss materials in the construction of those matching layers to avoid reducing the antenna gain.

We also showed that by combining a transmit array with a phased array antenna it is possible to obtain useful performance benefits. A phased array antenna was used to feed the transmit array and steer the main beam. The transmit array is used to boost the gain of a phased array at wide scan angles. For this reason, the side panels, of the transmit array, are rotated to align with the maximum steering angle. The transmit array employs a reduced number of reconfigurable unit cells compared with the conventional case. The advantage of this approach is that one can turn the gain of the transmit array on in the direction of the main beam and yet turn it off in all other directions. In this way we have demonstrated successful mitigation of scan loss without significantly increasing the lobe level.

Directional transmissions are usually employed in mm-wave communications in order to combat high path loss and avoid interference. It was a common belief that the narrower the beam we use in millimetre wave systems, the longer distance we can cover and the less interference to other users. The end result is increased signal to interference plus noise ratio (SINR), leading to higher system throughput. However, our research in this project revealed that a narrower beam will also necessitate a larger beam training overhead, which consequently decreases the system throughput. The design of a millimetre wave system should therefore strike a good balance between SINR gain and beam training overhead. Our latest research reveals that by using passive large intelligent surfaces one can create a smart radio environment, which turns a hostile wireless channel into a favourable one, resulting in a large power saving and more secure transmissions.
Exploitation Route We have demonstrated various different approaches for beam steering involving hybridising existing steering techniques: e.g. parasitics and phased arrays, lenses and phased arrays, transmit arrays and phased arrays. Our findings therefore highlight several possible antenna techniques that can be employed to achieve wide scan angle range or low scan loss, as required for various applications in mobile telecommunications and defence.

We have also analysed the trade-offs inherent in a range of different approaches. This new insight will help to highlight the best approach for someone wanting to improve a particular performance metric.

We are currently preparing a funding proposal on antennas incorporating Gallium based liquid metal in which we seek to address the key problems which currently limit the practical applications of this exciting new technology. We will do this by assembling a multidisciplinary team and taking a holistic metaphysics approach.

Our work on tunable phase shifters, operating at millimeter wave frequencies, having low insertion losses and a wide tuning range has attracted interest from industry. We plan to explore opportunities for developing the technology into a commercial product.
Sectors Aerospace, Defence and Marine,Digital/Communication/Information Technologies (including Software),Electronics,Healthcare,Transport

 
Description EPSRC Liquid metal engineering hub (LiME) Feasibility Study
Amount £30,000 (GBP)
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 12/2019 
End 05/2020
 
Description Antenna/circuit fabrication in China 
Organisation Beihang University
Department School of Computer Science & Engineering
Country China 
Sector Academic/University 
PI Contribution Supplied artwork for antenna/circuit designs which our partner in Beihang University fabricated for us.
Collaborator Contribution Our partner in Beihang University liaised with a PCB manufacturer to fabricate hardware prototypes for us.
Impact None
Start Year 2020
 
Description Beam steerable millimeter wave antennas based on liquid metal - State Key Laboratory of Millimeter Waves, City University of Hong Kong 
Organisation City University of Hong Kong
Country Hong Kong 
Sector Academic/University 
PI Contribution Knowladge and experience in using liquid metal for antenna applications
Collaborator Contribution Fabricating prototypes and making antenna measurements
Impact 1 conference paper and 1 paper in the IEEE Transactions on Antennas and Propagation
Start Year 2017
 
Description High gain omni-directional millimeter wave antennas - Inatel Brazil 
Organisation Instituto de Telecomunicações
Country Portugal 
Sector Charity/Non Profit 
PI Contribution Exchange of technical knowladge and experience.
Collaborator Contribution Exchange of technical knowladge and experience.
Impact 2 conference papers
Start Year 2017
 
Description Microfluidic network design 
Organisation University of Southampton
Department Southampton Nanofabrication Centre
Country United Kingdom 
Sector Academic/University 
PI Contribution Insight into: 1) the problems associated with current techniques for actuating (i.e. moving) liquid metal; 2) the ways in which we need to actuate liquid metal in order to create reconfigurable antenna/circuits.
Collaborator Contribution The partner has contributed: 1) expertise and knowledge of advanced microfluidic fabrication techniques and electrokinetics; 2) possible solutions to the problems with current actuation techniques; 3) help in writing a new standard mode EPSRC proposal.
Impact None
Start Year 2019
 
Description Phase shifting using liquid metal - University of Central Florida 
Organisation University of Central Florida
Country United States 
Sector Academic/University 
PI Contribution Knowladge and experience of using liquid metal in antenna applications
Collaborator Contribution New ideas and technical guidance
Impact During the visit the Professor from the University of Central Florida delivered a presentation to the research group. He and I also reviewed the technical results arising from a collaborative piece of research on the topic of phase shifters that can be reconfigured using liquid metal. Our collaboration led to the publication of the following paper: Khaled Alqurashi, James R. Kelly, Zhengpeng Wang, Carol Crean, Raj Mittra, Mohsen Khalily, Yue Gao, "Liquid Metal Bandwidth Reconfigurable Antenna," IEEE Antennas and Wireless Propagation Letters, vol. 19, no. 1, pp. 218 - 222, 2020. This collaboration began from initial discussions during which I presenting a range of research projects, to the Professor.
Start Year 2017
 
Description Rheology of liquid metal 
Organisation University of Surrey
Department Department of Mechanical Engineering Sciences
Country United Kingdom 
Sector Academic/University 
PI Contribution Insight into the questions that we have about the rheology of liquid metal as well as the problems that we would like to solve.
Collaborator Contribution Our partner from the University of Surrey has provided insight into the rheology of liquid metal. He has also prepared and submitted 2 small funding proposals on the topic that will help to investigate this topic further.
Impact We worked together to apply for funds from: 1) the Royal Society (£20k), and 2) EPSRC Future LM Engineering Hub Feasibility Study (£30k). That funding will be used to characterise the fluidic properties of Gallium-based liquid metal. The collaboration is multi-disciplinary and involves a mechanical engineer specialising in fluid mechanics.
Start Year 2017
 
Description Rheology of liquid metal 
Organisation University of Surrey
Country United Kingdom 
Sector Academic/University 
PI Contribution Insight into the questions that we have about the rheology of liquid metal as well as the problems that we would like to solve.
Collaborator Contribution Our partner from the University of Surrey has provided insight into the rheology of liquid metal. He has also prepared and submitted 2 small funding proposals on the topic that will help to investigate this topic further.
Impact We worked together to apply for funds from: 1) the Royal Society (£20k), and 2) EPSRC Future LM Engineering Hub Feasibility Study (£30k). That funding will be used to characterise the fluidic properties of Gallium-based liquid metal. The collaboration is multi-disciplinary and involves a mechanical engineer specialising in fluid mechanics.
Start Year 2017
 
Description Visit from Spanish researcher to Queen Mary University of London (QMUL) to undertake research of phase shifters 
Organisation University of Castile-La Mancha
Country Spain 
Sector Academic/University 
PI Contribution Devised the original idea of a phase shifter that could be reconfigured using liquid metal. Also researched and developed the technology on actuating liquid metal. Fabricated and measured the performance of the structure. Contributed to drafting the top quartile journal paper. Purchased all consumable items used. Funded Dr Borja's accomodation during the visit.
Collaborator Contribution Designed and optimised the performance of the phase shifter using the simulation tool. Drafted the top quartile journal paper. Helped to develop actuation techniques.
Impact 6th of June 2019 until 16th of July 2019 - Visit from Spanish researcher to Queen Mary University of London (QMUL) to undertake collaborative research. The target of the research was to develop a Substrate Integrated Waveguide (SIW) based phase shifter, operating at millimetre wave frequencies, which could be reconfigured using liquid metal. The visit was funded by the Spanish government. The outcome of the visit will be a top quartile journal paper. We also made a successful application, to the Spanish government, to fund a reciprocal visit by my Post Doc. and myself to the Spanish researcher's university. During that 1 week visit we planned to undertake further research on SIW based structures. Unfortunately, the visit did not take place due to the outbreak of the Covid-19 pandemic.
Start Year 2019
 
Description Presentation at City University of Hong Kong 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Professional Practitioners
Results and Impact Presentation at City University of Hong Kong. The presentation covered our work on novel forms of beam steerable millimetre wave antennas, including work from my previous PhD students: Marion Allayioti, Tim Hill, and Khaled Alqurashi. The work has led to further collaboration with Hang Wong at City University of Hong Kong. Hang Wong and I also made a successful application to run a convened session during the EuCAP 2020 conference.
Year(s) Of Engagement Activity 2019
 
Description School of Electrical Engineering and Computer Science Research Week 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact I presented a 3-minute overview of our research during the school's research open week. The event was attended by 16 delegates. The delegates included prospective PhD, MSc students, as well as industry partners. The event was recorded and has been made available via our YouTube channel: https://www.youtube.com/watch?v=iq4k1JbDguA. To-date it has received 40 views online.
Year(s) Of Engagement Activity 2020
URL https://www.youtube.com/watch?v=iq4k1JbDguA
 
Description Skype call with Li-ke Huang from Viavi Solutions 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Industry/Business
Results and Impact Skype call with Li-ke Huang from Viavi Solutions. During the call I described work that we have undertaken in QMUL on the topic of phase shifters than can be reconfigured using liquid metal as well as beam steerable antennas. Li-ke Huang expressed an interest in following that work closely with a view to possible commercialisation. We arranged a follow-up meeting on the 27th of March.
Year(s) Of Engagement Activity 2020
 
Description Wikipedia page on transmitarrays 
Form Of Engagement Activity Engagement focused website, blog or social media channel
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Wikipedia page on transmitarrays written by Tim Hill. Tim Hill was a student who studied for his PhD under my supervision. His research was aligned to this project. The page was only accepted for publication on the 12th of March and so it is too early to assess the impact.
Year(s) Of Engagement Activity 2020
URL https://en.wikipedia.org/wiki/Transmitarray_antenna