radio stations

[zlj1989]

I have a '99 Alero 4-door and I've had an aftermarket radio installed for a while now. The problem is that I've never been able to get in any radio stations clear. There's only one that I can really get in but its still not as good as the stock radio was. Also, my rear window defogger doesn't work. I'm thinking theres a broken cable somewhere. Could the rear window defogger not working be the reason I can't get in radio stations because the antenna is in the rear winshield? Or is there any way I can buy another antenna to have it work?