My own fan dipole array in the loft came about after remembering an old Ham friend from my childhood, (many years ago!!), who had such a setup much to the apparent bemusement of his radio colleagues. This idea does resurface every now and then and can be seen in the following article :-
Seemed ideal as I have a large loft and wire is cheap. (Unless you pay a company to cut the lengths for you!
I set this up years ago luckily before I became disabled for SWL activities and due to the use of discarded/surplus domestic mains wire I was able to press it into transmission use too. (With a homebrew Pi-Network ATU and RG11 feed.)
I had similar issues and questions until I came across 'Wireless Girl' AB2RA Janis and several of her articles. Her work with fan dipoles can be found here :-
But the main crux and as you have stumbled across already is the 40m/15m question which she explains eloquently here :-
Often as with many things we question 'conventional wisdom' now and then to find less than ideal if any suitable answers. Sometimes it's just a case of 'accepted wisdom' more than anything due to history or how many times it's printed.
Is it ideal?
Well, I'm still testing the transmission abilities but it has already proved itself exceptional as a SWL antenna and on my lowly 10 Watts I've had no issues. It's high up, fires through the tiles, (even when raining
), and best of all totally hidden so gets no disconcerting gazes from neighbours nor suffers weather damage. Flipping inexpensive too!
I had over the years started to pick up more noise thanks to modern electronics but the addition of a common mode choke eradicated that. So successfully that even my wife's hairdryer doesn't disturb a SWL session anymore!
Luckily I'm not firing hundreds of Watts through it or chasing 'rare' DX nor 'software modelling' it or even have the time to argue, ahem, discuss it ad infinitum. Antennas can be the proverbial 'quest for the holy grail' and I haven't enough years left for such adventures. It works admirably for my needs and I can fire up everything from 160m to 10m including WARC bands.
As always I wish you the best with everything you do Neal, but I've always enjoyed reading about your antenna adventures.
All the best