Hugh Griffiths

‘Engineers don’t often get much recognition’: Professor Hugh Griffiths OBE

Image credit: Nick Smith

Professor Hugh Griffiths OBE, a world authority on radar at University College London, has just been elected fellow of the Royal Society. Here he discusses how radar is going to play a significant role in the technology of the 21st century.

“It really does seem such an honour, because engineers don’t often get much recognition,” says Hugh Griffiths on being elected to the fellowship of the Royal Society. The 2021 elite cohort will, in time, Covid restrictions permitting, attend a ceremony in the Society’s storied halls in Carlton House Terrace, where he will be in elevated company. The Royal Society has counted among its fellows such names as Isaac Newton, Charles Darwin, Michael Faraday, Ernest Rutherford and Albert Einstein.

Fellowship of the Royal Society is awarded to those who have made a “substantial contribution to the improvement of natural knowledge, including mathematics, engineering science, and medical science”. It allows laureates to use the post-nominal letters ‘FRS’, which, for the onlooking engineering community, is confirmation that you have ‘made it’. This is further confirmed by how difficult it is to get elected and by the fact that the annual intake is limited to 52 new fellows, while there are only about 1,700 in total. “Some of the names really are quite incredible,” says Griffiths: “Maxwell, Turing, Hawking. To think that you’ve been put in the same league... there’s got to be some sort of impostor syndrome going on.”

Griffiths is best known for his long and distinguished career in the field of radar, in particular bistatic radar – “the bulk of my research” – in which the transmitter and receiver are spatially separated. This has the advantage over ‘more conventional radar’ in that “there is more information gathered from the directional properties of the scattering from the target”. He’s also conducted work with passive monostatic radar (“which is almost all radar systems”), where the radar receiver exploits existing transmissions such as broadcast, communications or radionavigation signals: “In other words, signals that are already there. We did some research in the 1980s and it’s now a pretty mainstream subject.” The passive configuration has applications in military radar sensing where the passive nature of the receiver is beneficial in the detection of stealthy targets, as well as in civil radar, as demand for spectrum from all users increases. He’s also got a professional interest in “biologically inspired signal-processing, looking at the way that bats vary their acoustic transmitted signal according to what they’re trying to do... navigation, intersecting prey. Those sorts of things.”

His short-form biography on the Royal Society’s website explains how Griffiths has “pioneered this subject over several decades in undertaking some of the first experiments on passive radar, and his work and publications have stimulated further work worldwide, to the point where passive radar is now a mainstream subject. He has also made measurements of the bistatic radar-scattering properties of land and sea, and of various types of target, including drones, birds and humans.”

While his job title at University College London is Thales UK/Royal Academy of Engineering Research chair of Radio Frequency Sensor Systems, Department of Electronic and Electrical Engineering, Faculty of Engineering Science, Griffiths thinks of himself as “a British, preferably Welsh, engineer”. Although he worked at Plessey for a few years designing and building adaptive antenna systems, the 65-year-old has spent most of his career in academia. In his teens he went up to Keble College at the University of Oxford where he read physics, captained the rugby XV and spent time rock climbing. “I don’t think I was a brilliant student. I didn’t get a first.”

“I was president of the Radio Society,” adds Griffiths. “But it was never about talking to people – it was always on the experimental side.” His interest in radio extended to radar (‘radio detection and ranging’) while working at Plessey, based at the Roke Manor research lab, on adaptive antennas, mostly for communications applications. In the late 1970s, “these were all analogue, and digital techniques were only just starting to be considered. Pretty much from the first day I had my own project that I was responsible for.” This interest developed further while doing his PhD at UCL, where, apart from a three-year stint at the Defence Academy College of Management and Technology at Shrivenham, he’s been ever since. During his tenure in London, Griffiths has published more than 500 papers and technical articles in the fields of radar, antennas, and sonar. He has received several awards and prizes, including the IET’s Harvey Prize in 2012.

Griffiths says that while it might feel as though the extent of the public’s knowledge about radar is restricted to pulsing lights on screens in World War Two submarine movies, in terms of real-life applications, there’s a lot more going on. “Perhaps the most obvious application for radar is in air traffic control. You can’t fly an airliner without radar to direct it. But it’s also used in meteorology: every night on our televisions we see weather radar maps. The technology is also used in land-mine detection and forensic applications. Radar is sometimes termed a ‘day/night, all-weather sensor’, so it works even when there is cloud cover, which means that the technology can be integrated into cars for collision avoidance and cruise control. There’s a whole range of other applications in the military: surveillance on aircraft, ships and satellites.

“It’s also used for Earth observation or remote sensing – things like the monitoring of the elevation of polar ice caps to see whether they may be shrinking or growing.” We digress to discuss the surface-penetration radar technology that polar explorer Pen Hadow famously man-hauled over the ice to the North Pole in the Catlin Arctic Survey International Scientific Research Programme (2007-2012). A fellow UCL alumnus, Hadow joined Griffiths on the Christmas 2019 edition of BBC2’s ‘University Challenge’ against the Guildhall School of Music and Drama. “Oddly enough, we didn’t disgrace ourselves.”

‘Networked sensing is part of the Internet of Things set of ideas and will happen without doubt.’

Professor Hugh Griffiths

With so many applications surrounding us, Griffiths contends that radar is a “very current” technology, “despite the temptation to see it as mature and we’ve solved all the problems. That’s far from the case.” This temptation stems in part from the fact that we’ve known at least something of how to sense the environment by means of reflected electromagnetic waves ever since German inventor Christian Hülsmeyer was the first to use radio waves to detect “the presence of distant metallic objects” at the dawn of the 20th century. (During his research, Griffiths found a recording of Hülsmeyer’s voice that provided him with “a vivid link back to the earliest days of radar”.) The jury is still out on whether this was radar as we understand it today. Yet Griffiths, who is also an expert and author on the history of the technology, makes the point that detecting reflected signals and measuring their range to build up a picture is still a rich field of multi-disciplinary academic research, “at a fundamental level applicable to military and civilian applications. Some of the stuff I do is explicitly military and is classified.”

An area where radar is likely to bring a significant impact in the 21st century is, says Griffiths, networked sensing. “Rather than having a single radar sending out a signal and receiving it, you have a whole network of sensors making their measurements, exchanging information, reconfiguring the form of that network in an adaptive and intelligent way. If each sensor were a cell-phone – they don’t currently have radar – for example, and they were all working together, you could build up a picture in an adaptive way. Network sensing, rather than single sensing, is a big one.” Griffiths explains that perhaps one of the best current uses for networked sensing is in cars. “At the moment they have individual radars, but you could imagine a situation where they are exchanging information between each other and with other kinds of sensors, so that traffic can flow unhindered. You can anticipate traffic jams and route cars in other directions.” Rerouting can be in response to fog or rain. In future, says Griffiths, we’ll join these networks via our smartphones. “It’s all part of the Internet of Things set of ideas, and it will happen without any doubt.”

The concept of networked sensors also has far-reaching implications for military applications. The sort of radar used on AWACS (Airborne Warning and Control System) aircraft, “great big things with rotating rotodomes on top of them, is hugely expensive” – in 2019 Nato announced that it was to modernise its AWACS fleet at a cost of $1bn – “and they can only be in one place at a time. Having networked aircraft working together is very attractive. This is because the system is reconfigurable and it’s flexible. Also, if you have a stealthy aircraft, the very last thing you want it to do is to transmit a signal that would give away its location. Stealthy aircraft that don’t transmit at all but can nevertheless pick up the echoes of other transmitters, are all part of this as well.”

Another big development, says Griffiths, “has been phased-array radar. With an old-fashioned radar system, the antenna moves physically, rotates mechanically, or whatever. These days we like to do that electronically so that the antenna stays fixed, and we move the beam all over the place really quickly, and that introduces a whole load of flexibility: it means you can have one radar doing lots of different jobs.”

One of the reasons radar has stayed relevant as a technology that continues to emerge while maintaining its viability as a research topic, is that it was given a significant boost by the arrival of the digital revolution, with the potential for more consumer radar applications increasing with the mushrooming of computer power. So, is it inevitable that as computing power becomes more ubiquitous and cheaper, we’ll get to see more radar in our lives? “Yes. The increase in computing power availability has an impact on so much. Moore’s Law tells us that computing power doubles every 18 months, and that will continue despite there being some physical limits (although I think that we’ll find ways around that).”

It follows that the increased scope of what can be done with that power will have “a huge effect on our lives. The original Moore’s Law paper is really interesting, quite apart from the fact that it is unusual for having a cartoon in it of people queuing up to buy a personal computer. That’s because this guy had a vision of what the future would be like. Of course, being senior in a big semiconductor company, he was in a prime position to make it happen. But you’ve got to remember that this was more than 50 years ago [‘Cramming More Components onto Integrated Circuits’ was published in 1965]. Even more interesting still, in Moore’s final paragraph of the paper he effectively says: ‘oh and by the way, this technology is going to have a huge impact on radar’.” (The final sentence reads: ‘The successful realization of such items as phased-array antennas, for example, using a multiplicity of integrated microwave power sources, could completely revolutionize radar.’).

We end with a counterfactual in which we imagine that Gordon Moore himself asks the final question in the interview: “Come on then, Professor Griffiths, tell me what you radar guys have done with my law.” The Welsh engineer focuses for a moment before explaining that “it’s enabled us to do so many things in making radar intelligent and adaptive. It’s enabled us to make radar images from satellites with incredible resolution. It’s enabled us to detect very small or stealthy targets.” The effective two-yearly doubling of computing power has meant that “we can now do so many things that we were previously unable to do”.

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