I live in the top flat of a building with a flat roof about 24' (7.5M) x 21'
(6.5M) and 30' (9M) above ground. I need an 80M antenna to operate locally
around the SE part of England. I have limitations on what I can erect.

I thought of a horizontal loop about 3' (1M) above the roof, possibly with
90uH to 100uH in each of the two side legs to help it resonate on 80M. I'm
not very good at modelling and could not work out how I enter a reactance
across the feedpoint to balance out the large negative reactance there. The
FFT plot with EZNEC looks promising.

Can someone help me to work out how to feed this antenna and what reactance
I should add at the feedpoint.

I have some options segarding the feeder and ATU. I have an SGS SG-230 ATU
which I could mount near the loop or an LDG Z-11 that I could mount near the
transmitter with a balun (I have several from 1:1 to 16:1) and balanced feed
to the antenna. My preferred feeder is 50 or 300 ohm balanced as they are
easily concealed or alternatively coax feeder and balun at the antenna.

Thanks for any help.
Richard (Dick) G4BBH