A Chinese research team from Southeast University in Nanjing have announced that they have found a way to change the way radar waves interact with an object. Researchers Wei Xiang Jiang and Tie Jun Cui used advanced metamaterials, sometimes used to guide light in unique ways, to similarly guide radio waves, thus changing how the object appeared in a radar scan. The New Scientist explains the experiment:
Copper conducts electricity well and reflects incoming radio waves, giving it a bright radar signature. To alter this behaviour, the team built a device made of 11 concentric rings of circuit boards etched with small metal-lined channels that prevent electromagnetic waves reflecting away. Instead, they guide the waves in a direction that the researchers choose specifically to make the hidden object appear to have different electrical properties.
Many of you are probably saying, “so what?” Admittedly, it’s not very exciting in and of itself that some guys were able to make copper look like porcelain to radar. But then one of the researchers says the magic words that will make your ears prick up.
Similar illusion devices could eventually be used for stealth technology: for example, to “convert the radar image of an aircraft into a flying bird”, Cui says.
There’s the payoff. Currently, stealth technology relies heavily on airframe shapes and materials to deflect or change how they are perceived on radar. The F-117 Nighthawk is a prime example of how shaping the airframe can dramatically alter the radar image.
The hypothetical device that the Chinese team describes has the potential to change stealth design by making many more aircraft designs stealthy with a device rather than a design. Something like a massive cargo plane could perhaps be made to look much, much smaller but still carry huge payloads.
There are, of course, limitations to the concept. Many stealth designs, like the B2 Spirit, use recessed engines to help mask the heat put off by the aircraft’s propulsion system. A radar cloaking device won’t be able to help with that, obviously.
Moreover, the Chinese device currently only works when viewed from one side, and the radar image was still the same size as the original object. This is a proof of concept, but the development of this technology will almost certainly shape the design of future aircraft.