Do you want the antenna to be removable without tools?
If so, I'd suggest some 3M heavy duty locking tape; it's not velcro or any other style of hook-and-loop. It instead interlocks pins and is very sturdy. I used a full covering on the back of my wireless heat controller, and it was almost impossible to remove from a RAM mounting plate. I had to cut waaaay back on the amount of the tape I used for the attachment, and it still does not come of without a fight.
I'm amazed at the level of adhesion that is achieved with modern materials.
Successfully surviving motorcycling since 1976.