Bill,
I've 'shorted' an 80 meter loop to load it as a
'sort of' 1/4 wave wire on 160 meters. Disconnected
the 'ground' side of the ladder line and connected
it to the 'hot' side of the tuner (with the 'other'
side of the ladder line). Certainly nothing to brag
about in performance, but it did work. I said a
"sort of" 1/4 wave wire because it's length really
isn't a 1/4 wave long. (Maybe a very 'fat', but 'short'
1/4 wave wire?) Probably didn't work very well because
I don't have any radials in the ground, just a very good
safety ground.
I suspect your 540 foot loop won't load the easiest,
but should make for at least a 'fair' signal on 160 if
you 'shorted' it. But, at 540 feet, you shouldn't need
to 'short' it anyway...
'Doc