[ChinaThreat]

It is a system that is not truely radar, but a passive system built on microwave detection technology. It looks at the sky and looks for any interruptions in microwave transmissions. Think of it as looking at a canvas, and any blemishes on the canvas would indicate an object. Many experts think the Yugoslavs used this and that is how they were able to shoot the Stealth fighter down in the Kosovo conflict.

[Bryan24]

I can think of a couple of ways to spoof that, and I'm not even a radar specialist or a military planner.

I'm willing to bet that the F-117 that got hit in Kosovo was visually sighted and then brought down.

[Blood of Tyrants]

My personal opinion is that it was a similar system developed by the Chinese that brought down our F-117. Thus the reason for the "accidental" bombing of the Chinese embassy a few days later.