After I cold night (10F), I awoke to see my passenger's side mirror cracked, so I buy a replacement and replace it. When I removed the old glass I saw that there was an electrical film behind it and I accidentally tore off on of the plug endings it had. I looked up what it was in the handbook, apparently
a heating element, but my used jag didn't come with that feature (its missing from my driver's side control panel, so I figured its okay. But when I went to drive it later I noticed my radio sounds like it just lost its antennae, which as far as I know is part of the back window glass. What did I really break?

 

It maybe coincidental, however the heating element in the mirrors work when you switch the rear screen heater on.

Maybe the earth has something to do with it

 

There isn't a separate switch for the door mirror heating elements - they work when the rear screen heater is switched ON.

Graham

 

vincent, first off, your car did have the side mirror heating elements. But, with what you most likely did, the one mirror no longer does. What I think is happening is that since you put the new mirror back on, that power wire is now acting like an antenna and it is picking up lots of interference from the outside world. It is getting shunted through the whole car and you are hearing it come out the radio. This can happen a few different ways. At a minimum you need to pull the mirror back off and insulate that wire so it is not making any accidental contact with any part of the body leading to other electrical issues.

 

Plus, it is a very common problem that when you have the rear defrost on the radio signal could suffer, especially on FM. Maybe just a coincidence you noticed it now. As far as I know there is no fix for that. I don't think that issue was ever addressed through the model years.