Key Point: Chinese scientists claim they have developed a new kind of material for making aircraft less detectable by radar.
But the development probably is not the breakthrough that some observers claim it is.
Prof. Luo Xiangang and colleagues at the Institute of Optics and Electronics, part of the Chinese Academy of Sciences in Chengdu, said they had created the first-ever mathematical model to precisely describe the behavior of electromagnetic waves when they “strike a piece of metal engraved with microscopic patterns,” according to South China Morning Post.
The newspaper cited a statement Luo’s team posted on the academy’s website on July 15, 2019.
“With their new model and breakthroughs in materials fabrication, they developed a membrane, known as a ‘metasurface,’ which can absorb radar waves in the widest spectrum yet reported,” South China Morning Post reported.
At present, stealth aircraft mainly rely on special geometry – their body shape – to deflect radar signals, but those designs can affect aerodynamic performance. They also use radar absorbing paint, which has a high density but only works against a limited frequency spectrum.
In one test, the new technology cut the strength of a reflected radar signal – measured in decibels – by between 10 and nearly 30dB in a frequency range from 0.3 to 40 gigahertz.
A stealth technologist from Fudan University in Shanghai, who was not involved in the work, said a fighter jet or warship using the new technology could feasibly fool all military radar systems in operation today.
Luo’s claims and breathless comment on their implications do not constitute a major change in the way companies develop stealth warplanes or the military balance of power among operators of such aircraft.
That’s because the metasurface Luo is working on is just one example of type of metamaterial that has been the subject of research all over the world. It’s not terribly new. If and when it begins to appear in front-line aircraft, it could improve stealth qualities in a wide range of aircraft on both sides of the Pacific Ocean.
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Metamaterials have been a popular research subject for more than a decade, Financial Times reported in 2018. “Metamaterials first captured the public imagination in 2006, when John Pendry of Imperial College published two papers showing how to create a Harry Potter-style invisibility cloak using the specially engineered materials.”
David Smith, professor of electrical and computer engineering at Duke University, who was a co-author of the research, went on to produce the first functioning cloak — although it made objects invisible to microwaves rather than to visible light. Now, the same technology is starting to be used in a number of commercial products.
Because certain metamaterials can control electromagnetic waves, they can also be used to improve the performance of satellite antennas and sensors. These commercial uses may be less headline-grabbing than an invisibility shield, but they show that metamaterials are coming out of the lab and into everyday use.
“These are the earliest pushes,” says Tom Driscoll, chief technology officer of Echodyne, which makes radar for drones, one of the products that uses the emerging technology. “It is a time when [people are] starting to emerge from their research or stealth development phases and ship general availability products.”
Lockheed Martin, which makes the U.S. military’s F-22 and F-35 stealth fighters, is a big investor in metamaterials. In 2017 the company partnered with a Canadian firm that produces lightweight metamaterials for solar-energy applications.
Metamaterials clearly are promising and, over time, could wind their way into various countries’ warplane-production. But they are not revolutionary.
South China Morning Post in a 2018 story gave voice to the skeptics. “There is debate in the research community about the value” of metamaterials under development by a research team at Southeast University in Nanjing, the newspaper explained.
“There is not a clear-cut definition of a metamaterial, so not everyone in the research community agrees with their claim,” a researcher with the Chinese Academy of Sciences said. “The consensus is that their product still has a lot of room for improvement.”
Image: Chinese Internet.