Originally Posted by DRMA
One thing to be aware of. When I talked to Van's technical support they said they do NOT recommend drilling any holes in the fiberglass cabin top that are not specified in the plans, as the fiberglass top is a structural member. So if you can mount the antenna below the cabin top, say inside the overhead console, without drilling any holes through the top, you should be ok. After a lot of reading and study, I came up with antenna arrangements that allow me to mount both GPS antennas, one Com antenna, and the ELT antenna all on the aluminum top skin behind the fiberglass cabin top, while still maintaining recommended spacing between antennas, ground planes, and distance from the vertical stab.
The second Com antenna is on the rear fuselage bottom, with the Xponder/ADS-B antenna forward in the tunnel but away from the gear legs.
I?m no engineer, and certainly don?t have any data to refrute Vans conservative recommendation, but I?m 100% confident that the two GPS antennas I have mounted to the top of my cabin and their associated holes have not significantly compromised the structure. Maybe I?m a fool and living on borrowed time so I guess ignorance is bliss. YMMV....