The system works by detecting minute disturbances in tv and radio waves as an object passes through the air. This makes it passive, i.e. no electromagnetic emissions and therefore VERY hard to find and destroy.
"stealth" aircraft are actually called low-observable for a reason. They have a small radar cross-section, but not a zero cross section. They are always seen by the radar, just not detected as aircraft.
Lockheed developed a system like the one described here some time ago-- used ambient and terrrestrial RF as the transmitter. Same thing works for super-advanced SONARS -- the systems listen for a moving hole in the background noise of the ocean. Makes it 'easy' to find "silent" subs if they move.
The secret to defeating a system like that is to give them what they are looking for.