Dan wrote:
I am toying with the idea of getting an aftermarket Gilsson antenna for
my GPSMAP 396 from www.gpsgeek.com. Has anyone had any expereince with
Gilsson antennas for aviation use? Supposedly they have better gain
than the Garmin units.

No idea for aviation purposes but I have a few for my Garmin V
automobile GPS (one semi-permanently installed in my car, and then
another for when I travel). All work very well. A million times better
than the standard one that came with the Garmin V. Not sure if the one
you plan on getting has magnets but they are removable from the antennas
I got.