I had XM installed back in June. I have the Alpine XM head unit with XM built into the HU. That set up came with the micro antenna which we mounted between the defroster vents on the dash. Seem's to work very good for me. Just the occasional drop out in heavily treed area's. But that's about it really.

 

Don't forget, guys, if you're getting a lot of dropouts, move the antenna someplace where there's a lot of metal underneath the antenna. It may work fine sitting on top of the dash, but if you're in an area that's iffy, you need to give the antenna a bigger ground plane to increase its sensitivity.

 

Mounted my Pioneer XM antenna inside the passenger side roll hoop works great top up or down.

 

Excellent info- I know this was an old cellular antenna rule of thumb but didn't know if the XM antennas were the same.

My XM antenna is also on the piece of metal between the trunk lid and the convertible top, works pretty well.

 

Its a useful technique for quite a few antenna types. The ground plane allows the antenna to increase its apparent length, thereby increasing its ability to pull in a signal. In some ways, it's like the technique of putting stuffing material into sub boxes to increase their apparent size.

 

finally got mine back from the paint guy (hacked it on ) noticed a big diffence already as the old one would drop out in my driveway but no longer - Thanks again John!!

a few pics

 

Bass,

Glad it worked for you. I guess it must be mounted on sheet metal in order to work. Looks much better painted to match the car!

John