You can use a combination of:
Mobile control tower, @ Avsim, file name="mct074rc.zip"
Traffic View Board, @ Avsim, file name="tvb_v2.1.zip"
FS9 Traffic Tool Box (FS9 Traffic SDK), @ FSDeveloper,
Traffic Tool Box
Mobile Control Tower is an "aircraft" that you can position anywhere and it makes use of the Eric Marciano freeware radar guage. It however will not track an AI aircraft, it's simply for viewing.
Traffic View Board tracks the AI, and is the most useful.
In the Traffic SDK, there are two nice AI trackers including a radar type display, these can both be run as separate windows in game.