What he ^ said. In the rear window, the top part or upper-detached part of the 'grid' is actually the fm antenna. Only the lower part of what looks like the heating grid will actually defrost the window.
Alright thanks. I was hoping that the black antenna was it, because I wanted to delete the stock antenna on my '68 Barracuda and replace it with the Challenger one. Now I'm not sure how I am going to do it.