Stealth fighters like America’s F-35 Joint Strike Fighter and F-22 Raptor are often touted as being “invisible on radar,” but they’re actually not invisible at all. In fact, all of today’s modern stealth fighters, including China’s J-20 and Russia’s Su-57, are pretty easy to spot on even dated early warning systems that have been in service for decades.Stealth designs minimize an aircraft’s radar signature, delaying and sometimes even preventing detection, but because of the physical requirements for tactical jets, stealth fighters can be easily spotted by certain low-frequency radar bands.