Art, KB9MZ wrote:
"I can up my efficiency to 50 per cent by hanging a wire down from the
dipole ends which I am not comfortable about---."

Why would Art be uncomfortable about improving efficiency by hanging a
wire down?
Maybe he does not believe his model is correct. Maybe he doesn`t want
some directivity change that comes with hanging a wire down. Maybe there
is some physical problem with hanging a wire down.

The problem with a loading coil is increased loss. Capacitance is
usually low loss.

As Yuri, K3BU has noted, there is much to be learned from reading
ON4UN`s Chapter 9 about antenna loading even though everything regarding
vertical antennas doesn`t translate readily to horizontal antennas.

ON4UN includes horizontally polarized antennas in "Low-Band DXing". It`s
easy to read, well illustrated, and full of good references. It helps if
you want to design your own antenna because it tells why as well as how.

Best regards, Richard Harrison, KB5WZI