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Stephen Chen

A groundbreaking radar being developed by Chinese scientists could detect and track F-22 stealth fighter jets using signals from China’s BeiDou navigation satellite system.
Using a simple receiving antenna, the radar is cost-effective, can be deployed almost anywhere on Earth and does not emit signals that might reveal its location.
Plus, if BeiDou is jammed, it can switch frequency bands to use GPS, Europe’s Galileo, or Russia’s GLONASS, ensuring uninterrupted operation.
In a peer-reviewed paper published this month in the Journal of National University of Defence Technology, the project team used an image of an F-22 Raptor, the most advanced stealth fighter jet in the US, to illustrate the radar’s hypothetical target.
Estimated performance data suggests this technology could also be applied to the detection of other stealth aircraft, such as the F-35.
China has a large number of anti-stealth radars along its coastlines and on its warships. But these radars are technologically complex and only affordable to a few powerful countries.




In smaller nations such as Yemen, Syria and Lebanon, Western stealth fighter jets can come and go freely, with little concern about getting caught.
The BeiDou radar could make anti-stealth technology more readily available, according to the project team led by Wen Yuanyuan, a senior engineer with the National Key Laboratory of Space Microwave Communication in Xian, Shaanxi province.
BeiDou, China’s global navigation constellation, has nearly twice the number of satellites as GPS.
When BeiDou signals encounter a stealth aircraft, they are refracted, creating unique echoes that scientists can analyse to make a fairly accurate guess as to the type of target and its position.
“With strength in all weather, global coverage, continuity, stable transmission frequency and precise timing”, navigation satellite signals provide an ideal source of external radiation to light up small and weak targets on a radar screen, Wen and her colleagues said.
But the signals refracted by stealth aircraft are extremely weak when they reach the ground, and the same satellite signals can also bounce off buildings, trees and other objects, causing strong interference and noise.

That is why until now it has generally been thought that passive radars require a dedicated set of antennas pointing straight at a satellite to obtain a direct and pure navigation signal. By comparing this reference signal with the signals received by another set of antennas, information about stealth aircraft can be extracted.
But this approach increases the complexity and computational burden of signal processing.
“Moreover, the dual-channel receiving structure is complex and carries a higher hardware cost,” Wen wrote.
Instead, her team proposed an unprecedented “blind detection” method using a single channel to identify stealth aircraft – without the need for a reference antenna.
This new design not only significantly cuts the cost of the radar but also makes its simple structure easier to deploy and more effective in resisting enemy interference during wartime, according to the researchers.
This breakthrough was made possible by a unique algorithm.
In 1991, when the world was still reeling from the end of the Cold War, Goran Zivanovic, a computer scientist in Belgrade, then the capital of Yugoslavia, invented a new method for detecting hidden cyclic frequencies in electromagnetic signals.
Following the publication of this algorithm, Zivanovic vanished from academia, and Yugoslavia dissolved a year later. His work received little attention, and for the past 15 years, no Western scientist has cited his articles.


But in China, his idea has been highly respected and widely applied in fields such as radar, communication and sonar.
Wen’s team upgraded the original algorithm to enable its application in the detection of stealth target signals.
In simulation tests, the algorithm successfully distinguished the distance, direction and speed of three stealth targets from radio noise.
China is harnessing a series of technological advancements to bolster its combat capabilities against the US military.
As well as navigation satellites, Chinese scientists are also developing other methods to catch stealth aircraft such as long-wave signals that can be reflected by the ionosphere, radiation produced by Starlink satellites and even electromagnetic waves emitted by US military base radars.
Some Chinese commercial satellites, empowered by artificial intelligence, have also detected and tracked F-22 fighter jets flying through the clouds.
The US is changing its Asia-Pacific strategy to counter the rapid progress in China’s military technology and capabilities. In June, the US military announced the transfer of around 10,000 soldiers from its military bases in Japan to Guam and Hawaii, locations farther from China.
Some senior Pentagon officials have expressed a growing preference for using drones over traditional combat aircraft in potential military conflicts with China.


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China

A new radar method developed by Chinese scientists is offering a cost-effective way to track stealth aircraft


A new radar method developed by Chinese scientists is offering a cost-effective way to track stealth aircraft.
