Surprising Negatives: Defying Accepted Norms in Circuit and Antenna Behaviour

Imagine a radar screen on which, instead of ‘blobs’, appeared images of the objects detected by the radio waves – from a ship in the ocean to a pothole in the road. Such a display system may not be too far off, thanks to world-leading research being led at Birmingham by Professor of Microwave Engineering Peter Gardner.

Peter – whose specialisms are antennas and circuits – is working on the so-called terahertz gap, an engineering term for a band of frequencies in the terahertz (Tz) region of the electromagnetic spectrum between radio waves and infrared light, for which practical technologies for generating and detecting the radiation don’t exist. At least, not yet.

The challenge, says Peter with more than a hint of optimism, is to go beyond accepted physics to bridge this gap and spawn new technologies with applications in the likes of additive manufacturing and micromachining.

‘The other really big application is imaging,’ he explains. ‘This is where a lot of our funding is coming from now for the Tz work, because the windows in the low Tz band are where we can propagate a signal that will enable us to do very high resolution imaging with very small antennas. A typical image is radar: instead of blobs on a screen, you would see detailed images. In the automotive industry, this is very important. When you reach high levels of autonomy, you want more information than simply “there’s something ahead, but we don’t know what it is”. Radar imaging would allow you to see textures in the road surfaces, so that you know there’s a pothole or an oil spill coming up, for example. This would enable the vehicle to prepare itself for what it’s about to encounter. So we are working closely with industry on this, in particular Jaguar Land Rover.’

This, along with other aspects of his groundbreaking work, featured in Peter’s recent Inaugural Lecture. His address was one of a series of Inaugural Lectures run by the College of Engineering and Physical Sciences to showcase its leading scientists who are pushing the boundaries in their disciplines. These events, which are open to the public and free of charge, mark an academic’s promotion to Professor (Peter was appointed in 2015), but also provide a rare opportunity to hear first-hand about their research.

‘I really enjoyed doing it,’ he says of the lecture. ‘I was able to use it as a way of talking about my research going all the way back to when I was doing my PhD, and even before that.’

Peter originally intended to go into medicine, but switched courses just weeks into his first degree at Oxford.

‘I’d always been very interested in electronics and engineering, but at school I got swept along with the idea that all the best people did medicine. So I actually went to Oxford to do that, but just a few days into it I realised it wasn’t what I wanted, so in the third week I managed to change to physics.’

After completing his BA with first-class honours, Peter settled on electronics as his particular interest, ‘so that was a natural direction for me to take’. It led him first into industry: from 1981 to 1987 he worked for Ferranti as a senior engineer in microwave amplifier development. In 1989, he embarked on a PhD at UMIST, researching microwave negative resistance circuits, low-noise MMIC design and tuneable planar resonators. In 1994, he joined Birmingham’s School of Electronic, Electrical, and Computer Engineering, where he has been ever since.

‘My first job here, as Lecturer in Electronic Engineering, was attached to (now Emeritus) Professor Peter Hall’s new Chair. Part of the reason I was recruited was that Peter was world renowned in antennas – it’s in large part thanks to him that our mobile phones are now so small, as he helped to pioneer putting antennas inside devices – so having a circuits specialist complemented his work. We had many productive years looking at all sorts of ways in which you could integrate circuit functions into antennas.’

Their research is behind a successful University spinout company, Smart Antenna Technologies, which launched its innovative single-antenna technology for mobile devices in 2013. This enables smartphone and tablet device manufacturers to replace several antennae with a single multi-band antenna, using a novel foil or printable antenna and control chip to produce a compact multi-frequency antenna. Its performance matches that of the separate antennae at their specified frequencies.

Now Head of Electronic, Electrical and Systems Engineering at Birmingham, much of Peter’s work focuses on finding ways to control antennas to make them smaller or with greater band width.

‘One of the trends we’re looking at now – and this was the main theme of my Inaugural Lecture – new ways of trying to challenge the fundamental limits of how well antennas can work. In some senses, it’s still very early days, but we have some new concepts that involve driving an antenna from more than one point. In other words, you could have two separate feeds and you could control the relative properties of those two signals feeding the antenna, in order to create some new possibilities for what the antenna can do. That includes making it smaller or making it operate over broader band width, or making it adaptable but in a way that doesn’t involve circuits embedded into the antenna itself, but involves a very precise control of the receiver properties of those two signals going in. That means the properties of those two signals can be brought into digital control in a much more precise way than we could before, so that you’re much closer to the idea of software-defined radio. We’re getting excited about that at the moment.’

A raft of academic papers has been published showing what the fundamental limits are on size, brand width and directivity of antennas.

‘Two examples we’ve generated with this technique show that we are meeting the fundamental limit. But the real challenge is to get beyond that – to go beyond accepted limits. If we can do that, then we really are going to make it.’