My idea I hope no one actually makes because I am from a country that spends a ton of money on makeing stealth, so I hope my idea doesn't work in some aspects but my idea is to basicly do what it's title says, detect stealths.
My idea is quite simple, most radar systems are capable of picking up
stealth aircraft but are not able to see that they are indeed aircraf because of ambient noise and interference.
My idea is basicly to have a computer program that takes only the high speed moving ambient noise and filters those out from the rest of the interference. So basicly it is looking for fast moving objects in the sky anywhere from 200 mph to mach 2.5 which is the speed that an aircraft would be traveling at.
You could use a doppler radar which uses the doppler affect to see speed of particles.
Since most birds don't fly at 500 mph like the B-2B, F-22, F-117 and later JSF will be flying at a radar system could determine that any object that appears the size of a bird or insect on radar that is moving at 500 mph must be a stealth aircraft or just a fly that got swatted really hard.