Radar plugin does not produce tracks. If you mean
radar trials they are not objects able to catch, more like graphics on
screen.
If you let radar_pi produce ARPA targets OCPN can track them as any
AIS target. Any
AIS, or own, tracks can be exported or "send to peer". See "Route & Mark manager" -> "Tracks" what's possible.
Is this an answer to your question?
Håkan