I've only recently come across 'flat-top antennas' after looking at pressing my paltry 44 foot doublet antenna into 160m action. (I've managed 80m and making contacts so thought I'd push some more!)
Have knocked together a link-coupled ATU with a fat T200 toroid that gets current up the wire and a 1:1 match but not managed any contact yet on 160m. (The old '1942' boys were booming through though!)
This same setup has been used on 80m by myself and managed to get some FT8 action in the log.
(Couldn't get into the usual rag-chew subject material to try a SSB 'break'.)
The original idea came about after reading this article :-
The shack is upstairs so all I got by adding an 'earth' was terrible noise and the laptop shutting down on transmit.
But I have started looking at 'Ground Tuning Units' or 'Artificial Earths' using a counterpoise. So far I can transmit with no ill effects to the shack, (or neighbours!), but my licence limit of 10 Watts hasn't rewarded me as of yet on 160m.
I wish you well with it Paul and thanks to Mike for pointing out such antenna options.
If anyone has anything to share on such subjects it would be most appreciated and should I come up with 'the goods' on my own experiments I'll be happy as usual to share any results/ideas.
Interesting stuff and fits the 'never say never' ethos well.
All the best,