Large portions of the craft were recovered, from the engine intakes to the exhaust to critical joints and things like the canopy.
IIRC, cell towers were used to look for the moving radio “void” in a computerized and decentralized method.
IIRC, the Chinese have been looking into that method. There has a lot that has been written about the F-117 shootdown over Serbia. I'm inclined to believe that the Serbs (probably with some outside help) took a fairly standard SAM radar & tricked it up to look for very small targets. This will work if you are looking at a very small slice of the sky and you know with some accuracy when the target aircraft is likely to arrive.
The cell tower method would likely involve a lot of sophisticated software and a degree of network reliablilty that might not have been possible for the Serbs. I say "might".