During the Kosovo War the 250th Missile Brigade equipped with the SA-3 'Goa' anti-aircraft missile system, downed a F-117A. According to NATO Commander Wesley Clark,and other NATO generals, Serb air defenses found that they could detect F-117s with their radars operating on unusually long wavelengths. This made them visible on radar screens for short times.
About 6 weeks later the Chinese Embassy in Belgrade is bombed. Looks like they found the radar in question!! Just should have checked the address before launching the HARMs!!!!