I have never used radar so this idea may be useless (ok, so almost all
of em are) but.....
Producing an intense burst of RF is fairly easy by firing a magnet
through a properly shaped coil. This is done in new EMP weapons where
the power output is high enough to fry nearby electronics. So, why not
use the same idea in a 12 guage shell dsigned to fit in one of those
flare launchers. The charge fires the magnet through the coil (this is
destructive as the coil disintegrates) producing a short intense pulse
of RF that will appear on the radar scope. Maybe it could also fire a
cloud of chaff into the air to make a longer lasting return. The idea
is that the initial pulse will get the operators attention and then the
chaff would allow him to see the source.