Originally Posted by vendo
I get same static when windshield wiper goes on...i didnt see any ground wires to check like the firewall one
What year/model is the car?
If your antennae is not in the rear defroster grid, then I cannot think of what would be causing the interference, then again even if it was, the fact that you also get it when using the windshield wipers, means it is not isolated to the rear defroster, which sounds like a bad grounding issue, if it is not that then I must admit I am stumped, I wish I knew more and could be of more help.
Did you try to disconnect the antennae as Mike suggested?