Porsche has an assigned bracket for the XM antenna under the passengers side wiper. Its found under the plastic cover just below the wiper. I had extremely poor reception with it placed there. I asked the aftermarket installer to simply disconnect the existing XM antenna and connect another with 25 or 50 feet of line so I could play with the placement. The installer said reception is better when there is metal below the XM antenna. What you saw in my pictures was the first and and only place I tried for the alternate placement. I live in Fairfield County, CT, where the roads are hilly and have a huge canopy of trees over them. Its the worse case senario for XM reception. I now have at the minimum of 97% good reception vs 60% from what I had before moving the antenna.
Alternate places where the installer said to he had placed the antenna were in the following places: 1. centered under the front bumper 2. centered under or above on the front dashboard as close to the window as possible. 3. for the cab layout: in the headliner just inside the front plastic sleeve.
Just a side note. XM antennas have vertex angle of reception of about 80 degrees that can be blocked by metal and the angle of the car. If the angle of the car is going downhill and the antenna is going away from the southern exposure of the XM satilite, the reception can be blocked. I have a cab so the placement works great with the top up or down. No metal to speak of to really block the signal.
Like I said in my thread, I looking at having the XM Commander taken out and going with the Cayenne module. The light at night from the display is quite bright. You can get information about this module from SunCoast Porsche, 877.923.1700.
Hope this helps, best
