I don't want to hijack the thread, but I have similar questions now that I've received my 25 watt GMRS radio kit from Rugged Radios. The kit has a half wave length 12 1/4" NMO antenna and mag-mount. No ground plane required.
I'm installing on a side-by-side which has an aluminum roof, but no portion of it is truly flat. I'm also somewhat obsessed with symmetry and having a "factory" look. The roll over structure has a center tube right where the antenna should go, so I was planning to use a pair of magnets under the aluminum roof (one on either side of the ROPS tube) to secure the mag-mount. The cable would run to the back edge of the roof, then down into the side-by-side.
Instead of the redneck triple magnet setup, I have a lathe and could make a hollowed-out raised ground plane disk with enough clearance over the roof and center ROPS tube to accommodate the NMO connection. The cable would enter the side-by-side via a hole in the roof under the ground plane/adapter. From my research, the ground plane should be a 6 1/8" radius to work with the 12 1/4" antenna assembly (stick plus base load). I'm guessing this ground plane adapter would wind up being about 5/8" tall, and it would be electrically coupled to the roof and side-by-side frame.
Is the raised ground plane adapter going to work, or am I mixing technologies (ground plane vs. no ground plane required) that shouldn't be mixed?
