Total posts : 45366
“The efficiency is improved simply because the radials reduce ground loss. Less signal lost in the ground-more signal radiated.”
Right, just so … but I cannot see how draping a wire across the roof and vertically down a wall could be considered a ground radial. Putting some wires radiating outwards from the base of the antenna flat on the roof (don’t go down any walls) would be much more like it, to prevent ground loss, but IMO even that should be attached to Earth ground in some way.
Otherwise, the ground of a wall wart or audio cable shield would have to do … inadequate for safety IMO.
The only way I can think of would be a metal vent pipe, which would be in a very old building, and might still be modified, i.e., corroded sections replaced with PVC, before it goes Earth, rendering it useless as a ground path.
Cap hats are, AFAIK, also considered part of the antenna, same as above ground radials, but as you say, these things are still up for debate.
Anyway, don’t let any of that stop experimentation … it’s where we all learn.