Scientists in western China have developed an anti-stealth radar so small it could be quietly and easily set up almost anywhere , including on a rooftop, according to the research team behind the project. Anti-stealth radar systems usually require a large antenna to pick up the weak signature of stealth aircraft equipped with technology to absorb or deflect radar signals. “Although the detection accuracy of the radar can be improved by increasing the antenna aperture, it will reduce the mobility and survivability of the radar platform,” said professor Yang Minglei in a paper published in the domestic peer-reviewed journal Modern Radar on August 11. The metric wave radar array developed by Yang, of the national laboratory of radar signal processing at Xidian University, Xian, and his colleagues, is similar in size and appearance to a clothes-drying rack, according to a photo published in the journal. The researchers said the mobile device showed superior performance in detection accuracy and range in a number of tests conducted on the roof of a university campus building. China has a multilayered air-defence system with anti-stealth radar stations, especially along the eastern Pacific Ocean and the South China Sea coastline. The Chinese advanced radars taking on stealth aircraft According to a public presentation in 2018 by Wu Jianqi, a lead scientist in the military’s anti-stealth radar programme, Chinese radar systems could detect and track American F-22 jets – regarded as the world’s most advanced and powerful stealth fighters – flying several hundred kilometres off the Chinese coast as early as 2013. The coating and structure of stealth aircraft can weaken or redirect high frequency millimetre-long radio waves . But the Chinese anti-stealth radar uses waves at much lower frequencies that are longer than a metre (3.3 feet). These low-frequency waves could interact with the stealth aircraft’s large components, such as its wings or tail, to produce echo signals more than 100 times stronger than those of military radar that operate at higher frequencies, according to Wu. Most metric wave radar systems are huge. Even mobile versions can be tens of metres high when fully extended. The devices usually need to be towed by large trucks and take hours to set up, making them easy targets for satellites and drones. In 2019, the Israeli air force destroyed a Chinese-made JY-27 metric wave radar in Syria. Although the device was believed to be a watered-down version of those used by the People’s Liberation Army, the incident heightened concerns about how well these anti-stealth platforms can survive, according to openly available information. The metric-wave radar system developed by Yang’s team consists of two identical antenna placed about 20 metres apart on the same rooftop, according to their paper. After one antenna emitted a burst of low-frequency electromagnetic pulses, the two antennas, linked by an optical cable, would work at the same pace to detect returning signals. The relatively large area covered by the dual-antenna array allowed the system to pick up more long waves that bounced off a target, according to the researchers. But the gap between the antennas also created extra noise or false signals that could affect accuracy. The idea of breaking a large metric wave antenna into several smaller ones has been around since the 1980s, but actual application of the technology remains rare because of instability and the degree of inaccuracy, according to Yang. How Pelosi’s Taiwan trip set off a new wave of US-China electronic warfare The Chinese team said they had developed an algorithm that could extract useful signals from strong background noise by analysing data collected by antennas in different locations. The data flow generated by the new radar was greater than usual, requiring four domestically produced Hunxin 1 chips, Yang’s team said. The Hunxin 1 is a coin-sized processor designed and made entirely in China with 55nm technology that is so old it cannot be affected by US sanctions on China . It has been widely used in Chinese cars, machinery and military equipment for nearly a decade because of its low cost, high performance and stability, even in harsh environments. “The chip has a quad-core parallel processing structure with powerful floating-point computing capabilities, which can very well meet the application requirements of high-speed real-time signal processing,” Yang said. The researchers could not be reached for comment by the time of this report. Due to the sensitivity of the stealth technology, the new radar’s actual performance in detecting real stealth aircraft remains unclear. But Yang’s team said they had been tracking many civilian aircraft with the system and the data suggested the technology worked. Elsewhere in China, scientists are working on other new anti-stealth radar technologies. A research team with the Nanjing Research Institute of Electronics Technology said in a paper published in the same journal last month they had developed a compact metric radar that could unfold like a budding flower, much faster than existing devices. Other research teams are increasing the power of high-frequency radar to increase the likelihood of detecting stealth targets and range. Chinese scientists are also developing quantum radar technology that can pick up signals invisible to traditional radar and technology and illuminate a stealth target with beams from several radar stations hundreds of kilometres apart.