How are the antenna for Sirius or XM installed? Do they hook up to the existing car antenna or is there a separate antenna somewhere?

Thanks

What I read is that the antenna for Sat. is incorporated into the new antenna style for the 05 model. But this does not make sense for those who updated software and now have sat. radio, unless the antenna was replaced. Dealer also told me that 05 had new antenna with built in Sat. My ex 04 LS430 had to have an antenna added that hid in the rear shelf and was painted same color as shelf trim.

I believe the XM and the GPS use the same antenna, but I'm not sure. Regardless, there is either one or two antennas under there for that purpose.