Originally Posted by
_Agrajag_
I don't know but a balloon carrying a corner reflector might well look a bit like a small drone, as long as there's a bit of wind in the right direction. I remember making some ad hoc corner reflectors from bits of cardboard covered with aluminium foil years ago. They worked just fine and gave a pretty solid return.
From everything I've read, the computers are usually set to eliminate contacts below a certain speed/size to avoid bird alerts (and balloons )