when the tints got replaced the antenna got damaged. (the reception is really bad now).
but Im not shure if it is the back or front glass where the antenna is. so I can fix the problem.

the FM antenna is on the top passenger side of the front windshield.

so whats on the back other than the defoger?

The 2K+ Bonneville has a Diversity Antenna system. This uses an antenna on both the front and the rear windows. The rear is AM/FM and the front is FM. The antenna module, when FM is selected, phase matches the signal from the front and rear to create the best possible signal. The radio sends a signal back to the antenna module indicating the signal strength and the antenna module adjusts gain accordingly.

What portion of the antenna was damaged? These are not repairable and the glass must be replaced.

From the FSM:
The diversity antenna system uses both front and back windows with an integral antenna built between the glass layers of the windshield and as an applique to the rear glass. Any damage to the antenna requires replacing the glass.

both the rear and front antennas got scratched with the knife. you can tell by looking at them that there are parts missing.

will something like this help my reception?
http://cgi.ebay.com/ebaymotors/New-F...spagenameZWDVW

The fact that both were damaged certainly explains why your reception is so poor. Did you do the tint yourself, or is there some sort of recourse with a shop? The eBay antenna shows it'* primarily tuned for FM signals and won't help much if you listen to AM. The other problem is connecting it to the antenna module. Connecting it directly into the back of the radio may be a possibility, but an adapter might be required.

I'm surprised about the front antenna. It is supposed to be located between the layers of glass and should be fairly difficult to damage. Do you have the original windshield?

You may want to talk with some glass and/or tinting shops. I'm sure these must get damaged from time to time. There may be replacement aftermarket applique antennas available. I've never looked into this, but it may be worth some hunting around.

The damage was done by a local shop. But since I was not using the car at the time, I did not notice until recently. & its been almost a year.