Chinese scientists say they have solved a fundamental dilemma inherent to radar. High-frequency radars, such as microwave radars, emit a lot of short pulses that are good for guiding weapons to a target.
Low-frequency radars, that emit waves that are meters long, are better for searching an area but aren’t precise enough for fire control (here’s a quick
primer). That means high- and low-frequency radars tend to be paired for search and fire control.
Stealth aircraft are shaped to avoid detection by high-frequency beams.
“Meter wave radars can detect stealth aircraft because modern stealth aircraft are mainly designed to avoid detection by microwave radar, and are less stealthy to meter wave radar,” said The Global Times.
“However, analysts previously said that because of their low resolution and accuracy, meter wave radars can only send warnings about incoming threats. And even if microwave radars compensate for the shortcomings of the meter wave radars, they are unable to entirely overcome these shortcomings.”
Wu Jianqi, a senior scientist at the state-owned China Electronics Technology Group Corporation, told Chinese media that his team has solved this dilemma.
“Wu solved the issue by designing
the world’s first practical meter wave sparse array synthetic impulse and aperture radar,” according to The Global Times. “Wu said that his radar has multiple transmitting and receiving antennas tens of meters high, scattered in a range of tens to hundreds of meters. They can continuously cover the sky as the radar receives echoes from all directions.”
https://asiatimes.com/2019/11/nowhere-to-hide-has-china-won-the-stealth-war/
German radar TwInvis
A German radar vendor says it tracked the F-35 jet in 2018
https://www.intelligent-aerospace.com/military/article/14067798/twinvis-radar-f-35-tracked
Countering Stealth Aircraft Technology: The Race to See through “Invisibility”
Russia’s Almaz-Antey 55Zh6M Nebo M is a 3-D high mobility digital AESA radar system, with three individual networked radars. It is Russia’s primary counter-stealth radar, developed specifically to detect and track stealth jets, UAVs and missiles and provide tracking data to SAM batteries and interceptor jets. The importance Russia attaches to it can be gauged by the recent announcement that 100 Nebo M systems would be expeditiously procured for Russia’s AD forces.
The Russian S-400 Triumf designed by Almaz-Antey is widely recognised as one of the most capable and lethal long-range AD systems in the world. Its AESA radar is claimed to be extremely successful in detecting stealth jets. It can engage all types of aerial targets including aircraft, UAVs and ballistic and cruise missiles within a range of 400 km. It can fire four different types of missiles with ranges between 40 and 400 km.
China’s JY-27A is a VHF AESA long-range air surveillance and guidance radar system. It is highly reliable and mobile, resistant to jamming, and can easily detect stealth aircraft such as the US F-22 and F-35. China has also developed the JY-26 radar that works in the VHF and UHF bands. Both these radars have a claimed maximum detection range of 500 km.
http://www.indiandefencereview.com/...hnology-the-race-to-see-through-invisibility/