Car Stereos: Radio unit under Windshield, auto glass company, antenna system

Question
Audi A4 2004 quattro

Because my windshield was broken by someone and I just
replaced a new windshield. But, after replacing it, my
radio can work. An Auto shop told me theres a unit (maybe
amplifier) is missing and he said it should be with
windshield. But, the auto glass company said he cannot find
anything. I want to ask "does that unit should come with
new windshield?" and "if I want to buy a new
amplifier(attach to windshield), where can i buy it and
which type?"

Answer
Hi Stephanie,

I assume you're talking about the rear glass, not the front windshield, because there's nothing in the front glass components that should affect the radio.

I'm not very familiar with the Audi's antenna system; your best option would probably be to contact a local dealer's service department.  However, from what I can tell, the actual antenna aerial is integrated with the rear glass, while there's a booster module mounted above the glass, under the headliner in the rear.  The replacement glass should have included the built-in aerial, but not the booster.  Of course, even if your new glass included the aerial, it wouldn't be effective unless it was connected to the system; and the fact that they couldn't find the booster is a pretty good indicator that it's not connected.  

Hope this helps!

Brian