Taking radar to another level

12 March 2013
IET's 2012 AF Harvey Engineering Research Prize winner Prof Hugh Griffiths FIET

Making good use of the IET research award: Prof Hugh Griffiths, Royal Academy of Engineering/Thales UK Chair in RF Sensors.

International Space Station

Space is full of junk that is potentially lethal to astronauts on the International Space Station.

Space debris around the Earth

It may not be immediately obvious, but space is full of junk.

Radar dish

Radar technology has been with us for more than a century.

Mature technologies such as radar don’t grab the headlines much these days. But as the IET’s 2012 AF Harvey Engineering Research Prize winner Hugh Griffiths says, there is still plenty going on. Words and portrait by Nick Smith.

Walking into Hugh Griffiths’ office at the Department of Electronic and Electrical Engineering at University College London, the first things to grab the visitor’s attention are a bunch of daffodils and a rather impressive globe. The flowers are a nod to his Welsh background and by extension his passionate interest in rugby. The globe will become a prop when he sits for his portrait photograph. In the first of many good-natured exchanges, we decide that we’ll try to keep the word ‘global’ out of the headline.

Griffiths is one of the big names in radar research, specifically bistatic radar, and as one of its non-military uses is geophysical remote sensing, the globe serves as a reminder of the international importance of his work. He has just been awarded the 2012 AF Harvey Engineering Research Prize from the IET. The £300,000 cheque will enable him to continue his investigations in bistatic radar.

By his own admission his job title is a bit of a mouthful. As he gives me his card I carefully copy the words ‘Hugh Griffiths, Royal Academy of Engineering/Thales UK Chair in RF Sensors’. If I were to ask him only one question today it would be simply that of how he is going to spend the money.

“I’m going to continue my research programme on measuring and understanding bistatic radar clutter and target signatures. Here at UCL we have our own bistatic radar in the lab upstairs and basically what I want to do is to extend the operation of that radar to different frequencies, and to improve it in a number of other ways that will help with our understanding of that phenomenology.”

While extremely welcome, it isn’t simply the money that makes the award so important. “The recognition is valuable too. It says that we are doing world-class research here at UCL, and that means a lot to me. Then there is the ability to do further research in an unfettered way. I’ll be able to make good use of the award.”

Bistatic radar is a branch of the discipline where the transmitter and receiver are in separate locations. According to Griffiths, this introduces “a number of complications. First, the receiver needs to know the very instant each pulse is transmitted, which means that there are synchronisation and geolocation issues.”

But there are advantages to bistatic over conventional radar systems, especially in military applications. The receiver is passive and does not radiate a signal, which makes it hard for an enemy to detect and destroy. It’s also hard to jam. Griffiths says that should an enemy wish to jam a bistatic system (assuming it has been detected), “the jamming will have to be spread out over a wide range of angles, which dilutes its effectiveness.” He goes on to say that bistatic may also have advantages in detecting stealthy targets (“details of which, of course, would be classified”) and it is also compatible with unmanned aerial vehicles (UAVs). “In this case the transmitter, with all its weight and power consumption, can be somewhere else and the receiver can be on a small lightweight platform such as a UAV.” And that, says Griffiths, is “very interesting.”

As well as the continuation of his prize-funded research, Griffiths is looking into the detection of space debris. It may not be immediately obvious, but space is full of junk that can damage satellites and is potentially lethal to astronauts on the Space Station. “Every now and then you will hear reports that the astronauts have had to evacuate to their escape capsule, just in case they’re going to be hit. If you look at a graph of space debris versus year you’ll see that it increases steadily.” There are two step changes on the graph, one of which is when China shot down a satellite with a missile (“which made an awful lot of debris”). The second is when two satellites collided accidentally. “It takes just the tiniest piece of debris to cause a lot of damage. So being able to detect the debris is an important part of what needs to be done. What you then do to clear it up gets more difficult.”

Another area of Griffiths’ research is spectrum congestion. The electromagnetic spectrum is a finite resource with lots of users – broadcast, communications, wireless, radar, radio navigation – all wanting a bigger slice of it. And it comes at a premium. When the government  auctions off chunks of the spectrum to cell phone companies, they can expect to pay “literally billions of pounds.” Griffiths says that “it is very likely that bistatic radar will have a part to play in relieving that congestion. We’re quite interested in radars that don’t have their own dedicated transmitter, which just make use of existing transmissions, such as communications, broadcast or TV.”

He asks me if I remember the ‘ghosting’ effect that used to spoil the experience of watching our old analogue TVs. To most people this was a nuisance, he says. But where others see a bad picture, he sees radar, which if harnessed properly can be used to detect and track aircraft for 100km or more. “We are starting to think that we will want to design communications waveforms not only to deliver their primary purpose, but so that they can be deliberately used as radar.” This needs to be addressed because “there is only one thing you can predict about spectrum congestion with any certainty, and that is that it’s going to get worse.” Griffiths also predicts that there will be issues with the new WiMAX wireless standard, due to it sharing spectrum with a formerly exclusive radar band.

A lunar start

Griffiths recalls being interested in electronics from a very early age. He remembers as a nine-year-old building a crystal set with his father. His headmaster also gave him a transistor radio (“which I dismantled”) that led to a teenage interest in ham radio. “But it was never just about talking to people. I was always interested in the experimental side, building new pieces of kit and bouncing radio signals off the moon, or off meteor trails and things like that. I learned a huge amount from that. The moonbounce was great. We built a 20-foot diameter dish out of scaffolding and chicken wire and… it worked!”

He went up to the University of Oxford in the 1970s where he read physics at Keble College and played a lot of rugby. Afterwards, he worked in industry at the research laboratory at Roke Manor, “which in those days was part of Plessey.” At Roke he worked on circular antenna arrays and became aware of similar research being carried out at UCL by Professor DEN Davies. “I was interested in doing a PhD as well as the bright lights of London, and so I wrote to him. Davies, who among many other appointments was Chief Scientific Advisor to the Ministry of Defence and president of the Royal Academy of Engineering, has been a great influence on my career. At that time we had a really interesting system here, where we were using as the source of our bistatic radar experiments air traffic control radar at Heathrow Airport. We were able to set up out own radar here using someone else’s transmitter. I also worked on space-based sensing for remote measurement of the topography of polar ice sheets, effectively trying to see whether the ice was shrinking due to the effects of global warming.” At the time, Griffiths recalls, “that was quite an unusual idea.”

Following his PhD, Griffiths was offered a lectureship at UCL where his career developed: he served as a professor and then as head of department for five years, before temporarily stepping outside London for a three-year stint at the Defence Academy at Shrivenham. “That was terrific fun. I really enjoyed working with the military. But it was really an administrative role and I missed doing research.” Griffiths returned to UCL to take up a chair funded by the Royal Academy of Engineering and Thales UK, which is “what I’ve been doing for the past four years.”

Working with the IET

Apart from being the recipient of the AF Harvey award, Griffiths has strong links with the IET. “I’ve been a Fellow for a long time.” He looks up at the wall to see if he can locate his fellowship certificate. It’s not an easy job as there are dozens of framed accolades to scan through. Eventually he gives up, and reflects that he was “heavily involved in the early stages of my career back in the days when the IET was the IEE.” He was “for many years” chair of the Radar, Sonar and Navigation Professional Group and has been the editor of the Radar, Sonar and Navigation Journal “for a long time.” He edits a series of books for the IET and served as chair of the Scholarships Committee.

I ask Griffiths what he thinks are the most important challenges facing the engineering community at the moment. “In broad terms, I’d say that it is the requirement to harness technology for the benefit of mankind. Heaven knows the world faces some pretty dire problems in the near future: global warming and overpopulation are just two. Potentially technology is the only means of solving these problems. But this requires governments understanding the value of what we do.” He explains that funding for technology in the UK, as a proportion of national income, is less than in other developed countries. He points out that few politicians in the UK have a scientific or technical background, which leads to investment in technology being seen as an expensive drain on resources. “Also,” he says, contemplating the globe on his meeting table, “so many of the problems we face are international. Recently there have been restrictions on universities taking people from other countries. To my mind that has been very counterproductive because engineering and research are international subjects.”

Griffiths needs to get back to work. But for his parting thought he assumes another of his roles: chair of the Campaign for Science and Engineering. “What we do at CaSE is try to get politicians of all kinds to take science and engineering more seriously.” He admits this is difficult when the challenges have time constraints far longer than the four-year self-preservation cycle that preoccupies our politicians. He says that maybe we should turn our attention to how longer-term problems are solved in different parts of the world. “In Saudi Arabia, for example, they understand that they can’t rely on generating wealth from oil for ever. They understand that future prosperity will have to come from technology, and so that is the direction in which they are moving. And this is how we have to think in future.”

For further information on UCL’s Department of Electronic and Electrical Engineering go to www.ee.ucl.ac.uk

Research notes

Radar technology has been with us for more than a century and plays a vital role in air traffic control, environmental monitoring and defence. Future challenges such as the congestion of the electromagnetic spectrum mean that conventional approaches to radar will be overtaken by intelligent, adaptive and distributed systems in the future.

The Department of Electronic and Electrical Engineering at UCL has a long tradition of research in microwaves, radar and optics, dating back to its foundation in 1885 by Professor Sir Ambrose Fleming, inventor of the thermionic valve and constructor of the equipment used by Marconi for the first transatlantic radio communication in 1901. Over the years, Professors Harold Barlow, Alec Cullen, DEN Davies, John Forrest and Hugh Griffiths have maintained and built on the impressive stature of the department in this area.

Its main areas of research are radar and sonar systems, antennas, phased arrays, microwave and MMIC circuits and computer modelling of fields, with funding from a wide range of sources including DERA, EPSRC, EC and numerous UK industrial partners. The group is currently led by Professor Hugh Griffiths and involves 11 full-time and visiting members of academic staff and some 16 postgraduate students or research assistants.

Bistatic and multistatic radar systems have been studied and built since the earliest days of radar. As an early example, the Germans used the British Chain Home radars as illuminators for their Klein Heidelberg bistatic system. Bistatic radars have some obvious advantages. The receiving systems are passive, and hard to detect. The receiving systems are also potentially simple and relatively inexpensive. Bistatic radar may also have a counter-stealth capability. Bistatic radar systems can use VHF and UHF broadcast and communications signals as ‘illuminators of opportunity’, at which frequencies target stealth treatment is likely to be less effective.

Over the years a number of bistatic and multistatic radar systems have been built and evaluated. But few have progressed beyond the ‘technology demonstrator’ phase. Interest in bistatic radar tends to vary over a period of approximately 15 years, and we are currently at a peak of that cycle.

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