Perhaps "antenna experts" can add clarity or correction to this, but here is my understanding in regards to metallic tube fuselage structures like our Kitfox designs... I have heard that a full 1/4 wave ground plane in the form of a disc or plate is not necessarily needed. Something much smaller, if properly attached and grounded to the fuselage structure seems to work very well, as per the experiences of a whole lot of builders/flyers. I've been told that the fuselage tubing/structure itself becomes an extended part of the ground plane, working very effectively in most cases... FWIW.