Microwave absorbing circuit can enhance plane stealth

A team of Chinese researchers have made a breakthrough in stealth plane technology that could be so significant even local military sources say it should be kept out of the public realm.

The team released the technical and design details of an “invisibility circuit” they claim has the potential to help aircraft trick the best early warning systems in use today.

The researchers are affiliated with the Huazhong University of Science and Technology in Wuhan in central China’s Hubei province.

According to their paper, they have created a multi-layer electrical circuit that can “trap” microwaves at ultra-high frequencies, thus confusing radar systems and enabling aircraft to sneak past them

What is unique about the latest finding is that the material used to create the circuit would be almost impossibly thin. At under one centimeter, it is just a tenth the size of similar products developed by overseas competitors. This means it could be used to coat planes for the first time, pundits say.

Stealth planes including the F-22 and F-35 used by the US military are not quite as evasive as they sound, according to Huang, who said they can be spotted by advanced radar systems even from a considerable distance.

Such radars typically use microwaves at strengths of 2 gigahertz or lower to identify and track stealth aircraft. This is because the currently available coating materials can only absorb electromagnetic waves at high frequencies.

Jiang’s team said the new circuits hit the military’s sweet spot as they can absorb waves ranging from 0.7Ghz to 1.9Ghz.

Many similar projects are kept under wraps because of their implications for national security and national defence. Some are supported by military funding, which prohibits their public disclosure.

The new circuit is not without problems.

First, it is unable to absorb microwaves generated at frequencies of 2Ghz or above, meaning that it could still be spotted by advanced radar systems, some of which can operate at over 40 Ghz.

As such, it could take years before it is used on an actual aircraft, Huang said.

It may initially be applied as an undercoat beneath other cutting-edge paints that are already used on stealth planes, he added.