Someone asked me how this antenna worked after I had built the Q section
from two pieces of 50r coax side by side, using the centre conductors as
an open wire feeder equivalent. The shields being joined at each end but
nowhere else.. (There should be grounded at the bottom end and at some
neutral point at the top - if any)

The antenna is a almost equilateral triangular shaped single quad loop
with base/feed about 4 metres off the ground. The "almost" being the
horizontal/top section is about 8 metres in length.

Well it works! I dont have enough of a power supply at the moment for
doing any extensive on air tests. VSWR was 1.4:1 without much excursion
at the band edges. This is what 4NEC2 said it would be. In fact I didnt
have to cut it after following the modelled dimensions. It was
surprisingly wide band I guess from the higher feed Z (rather than using
a single 75r section)

I have only just moved here and there is a lot of noise about at various
times of the day. (S7-9) I have heard stations across the US and maybe
some Spanish speaking. Waiting for a PSU to arrive so I can try a little
harder.

I didnt notice any VSWR changes or a change in feedline radiation
(through PC/stereo spkrs etc) by coiling the coax at the base of the Q
section. Indeed I did it because I was at risk getting tangled in the
coax going to the trash can!

I expect high radiation angles BTW.

Cheers Bob W5/VK2YQA East Texas.