I've used radar in sweep mode for Sparrows quite a bit so I could pick and choose my targets better. Keep in mind, I have difficulty settings on normal. Accidentally toasted a squadmate once -doah.
When your radar is sweeping level off a bit and hit the default HOME key to cycle through targets. Then hit the default Insert key to make your radar lock-on to the target that is now in brackets on your radar. At normal difficulty you can then hit Ctrl-R to visually target your currently locked and get info on it. Ctrl-R doesn't always work for me, but that's most likely because it's out of sighting distance.
By then, you should have it all locked up just fine. Fire, and keep him in your HUD.