I just noticed that my OB 04 that I just purchased has no antenna. No signs it had at one point either. The radio reception is okay tho. 
Correct. I replaced my headunit and didn't plug in the power antenna wire at first. There was no reception whatsoever. Otherwise, it seems to work just as well as a conventional mast antenna when powered.The glass antenna does have a small catch. There is an antenna preamp in the rear hatch. Mine just died due to a broken power wire in the rubber flex boot at the top of the hatch. When the preamp dies, the FM gets weak, and the AM reception goes away almost completely. I will be soldering wires to fix it later today.
I believe that the 02 has the antenna in the rear side window glass. The preamp would be inside the panel near that window. If you have an aftermarket radio, chances are the wire that powers the preamp did not get connected in the dash behind the radio.I just bought an 02 OB and put in a nice radio I had in my last Subee.
However, the FM is weak and I get no AM
So maybe I have the same problem as Radar.
If you are still out there [I realize the last post was well over a year ago], could you tell me the outcome of your antenna booster project, and just where to find it. Is it in the spare tire compartment? Or closer to the rear seat?
Did you have to buy another one?
Thanks