More than 290 radar experts from 15 countries congregated in Adelaide in mid-September for the Radar 2013 International Conference.

Over four days, their presentations illuminated a changing landscape for radar, dominated by ever increasing demands on a finite electromagnetic spectrum, the enabling effect of recent step changes in computing power and the rise of the civil market for commercial radar systems in applications from bushfire monitoring to vehicle safety.

Radar 2013 came to Adelaide through Australia’s involvement in the five-nation conference member group, with the engineering or electronic engineering institutions of France, China, Britain and the US also hosting in turn. Financial constraints in Europe and the US reduced their involvement with this year’s conference, but organisers were impressed with the quality of the papers presented, an impression confirmed by post-conference feedback from delegates.

China’s keynote speaker, East China Research Institute of Electronic Engineering Deputy President Dr. Jian-qi Wu, provided an insight in to the state of Chinese counter-stealth radar research. His presence was something of a victory for organisers, according to conference international liaison chair, Adelaide University Adjunct Professor Don Sinott.

“There have been restrictions from both sides on their ability to send people to Australia and give meaningful talks,” Prof Sinnott said. “So getting a prestigious figure like this professor to come and speak was quite a coup.”

Dr. Jian-qi Wu’s presentation detailed Chinese experiments with metre-wave radar in detecting stealth aircraft. Although metre-wave offers unique frequency band advantages for detecting stealth aircraft, its historically low detection accuracy and inaccurate height finding have seen it progressively replaced with common microwave radar in many applications. But Chinese tests with the meter-wave synthetic impulse and aperture radar (SIAR) and super-resolution processing have shown that it is possible to overcome these drawbacks effectively, suggesting the system is worth of more development as a counter-stealth system.

The theory and technology were not new to conference delegates, but the candour of such an eminent Chinese radar expert was.

“I think the subject was somewhat surprising in that he talked about Chinese programs for counter-stealth radars which, if you go back a decade, nobody was allowed to talk about the word,” Prof Sinnott said. “It was quite a step forward.”

Radar conference chair, DSTO’s Dr. Andrew Shaw, said Dr Wu’s presentation was another reminder of China’s progress in radar development, in a nation which graduates more new radar engineers in a year than Australia has in total.

“The other thing that shows up in the Chinese attendance is how far they’ve progressed in the past 10 years,” Dr Shaw said. “The sheer number of radar scientists that they are generating is stunning. And the quality of their work is quite notable.”

British speaker Professor Hugh Griffiths holds the Thales/Royal Academy Chair of RF Sensors in the Department of Electronic and Electrical Engineering at University College London, England. His keynote address “Where Has All The Spectrum Gone?” detailed the proliferation of transmitting devices in all areas of the electromagnetic spectrum and the trend of allocating formerly “radar-friendly” sections of spectrum for dedicated communications.

“Advances in radar and communications over recent years have put increasing pressures on the electromagnetic spectrum,” Prof Griffiths said. “Increased signal processing power has allowed wideband high resolution radar waveforms to become an increasingly common option on modern military systems.

“Meanwhile, miniaturisation has allowed commercial communications companies to provide ever more complex services to mobile systems, which require much larger bandwidths than those used in the past, particularly because of the demand for wireless streaming of video to mobile devices. The prices paid by telecommunications companies for a few tens of megahertz are indicative of the financial value attached to the spectrum and it is not necessarily easy to see how radar can compete in these terms.”

The problem is compounded by the fact that communications users have successfully lobbied the International Telecommunications Union (ITU), which controls spectrum allocation, to have radar systems downgraded from primary to secondary status in some parts of the spectrum, in favour of communications transmission. A secondary status user can only transmit if they can do so without interfering with primary users.

“Over the last 10 years, wireless industries have lobbied their member nations within the ITU to downgrade radar in the 3.4-3.7 GHz band to secondary status as well,” Prof Griffiths said. “Currently, the big competitor for the 3.4-3.7 GHz band is 4G wireless communications (WiMAX or LTE, though all indications are that the latter will dominate).”

Prof Sinnott agreed, and said the issue is well known in Australia, affecting even the nation’s best known radar system.

“It’s not a new problem, but it’s a mounting problem,” he said. “I guess a good current example of that is in the high frequency spectrum, maybe five or six megahertz, up to 30 megahertz, which has traditionally been very heavily used. And what operates in that? Australia’s Jindalee Over The Horizon (JORN) radar.

“So the licence that’s held by the folks that run that radar is basically a non-interference one that they can use a band if it’s not being used by somebody else. And a key to that is that the spectrum is continually held under surveillance and the JORN system will use a spot. But if somebody else comes up that has legitimate reason to use it and has the licences, then JORN has to move. And that’s what’s done.”

New design directions

With the demand for communications unlikely to decrease, radar designers are taking advantage of technology advances to produce cleaner signals, with less sidelobe diversion from the target frequency, to minimise interference and maximise useful data in the returns. They are also devising various means of sharing the spectrum with new players. Concepts such as sharing bandwidth on a time basis, transmitting when no one else is transmitting, or on a spatial basis – transmitting in a geographical area where another user is licensed to operate, but isn’t, are just two of the options.

Another solution is itself a function of the exponential increase in electromagnetic energy already being emitted by the proliferation of devices such as mobile phone towers – passive radar.

“Talk about passive radar, reinvention of passive radar, has been really noticeable over the last couple of radar conferences,” Dr Shaw said. “It’s something we’ve always known is a good idea but there have always been issues with it. Essentially the waveforms that were out there were not good and the computational power you needed to do the processing was not good.

“What’s really happened in the last four or five years is all the waveforms of any real significance are now digital and because of the nature of the comms signals they’re transmitting, they’re not perfect for radar but they’re very good. And when they’re essentially free, very good has a lot going for it.”

Dr Shaw said that while the requirement for stealth is a factor in some passive radar applications, competition for spectrum is often the driver.

“There are many applications for which an active radar is still by far the best thing,” he said. “But there are also a whole range of applications where we can’t use a radar any longer, or we’re so constrained with what we can do with a radar now that whilst a primary radar would be better, better than nothing is the trip wire radar which we can use passively, which we can then say now there is something interesting, let’s go and look at that with something else.”

Commercial applications

Another conference theme could perhaps be seen as the inevitable outcome of shrinking defence budgets – the rise of commercial radar applications.

A conference paper by Melbourne University’s Rob Evans painted a picture of a future where every car, and possibly even bicycles, will have multiple small radars for applications such as proximity warning and guidance, thanks to development of cheap, easy to produce “single chip” radars at prices with production costs of only a few dollars.

These radars are also being eyed for military applications, including micro-UAVs and, when issues of power supply are eventually solved, even the ability to “sow” an entire battlefield with thousands of small, expendable chip radars.

“Radar on a chip is one of the things that’s going to make a really big difference in the next decade,” Dr Shaw said. “Defence has only ever bought tens of radars at most of any one type. So it’s always been a small market. But if you put just one radar in each corner quadrant of a car, that’s four per car. Put 10 million cars on the road, that’s 40 million radars on the market.”

Radar designers are learning fast, about both the manufacturing possibilities accessible through high volume (TR modules for a recent phased array radar project were manufactured on a mobile phone production line) and the different requirements of the civil world compared with their traditional military customers.

“I remember hearing one fellow apologising to a car manufacturer saying we’re not going to get 10,000 hours of life out of this system,” Dr Shaw said. “The car manufacturer was laughing. And he said have you ever looked at how far a car’s gone when it’s driven for 10,000 hours? That’s several times the lifetime of most cars. So it’s a whole different paradigm from an engineering perspective.”

Prof Sinnott believes continued involvement in the Radar Conference has great value in keeping our local radar researchers connected with nations where radar research is conducted on a larger scale.

“The fact that it comes to Australia every five years is a golden opportunity for Australian researchers in radar or related fields,” he said. “Having Australia in this club is particularly important in terms of networking. Once the conference is over and people go back to their desks, they’re on the e-mail and they’re talking to people overseas and connecting in ways they haven’t in the past.

“From my research experience the most valuable thing I ever had was my network of expert contacts and that’s what we hope will grow through this conference.”

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