http://kf4bwg.com/ There seems to be two kinds of horse fencing of interest.

The flat braid with wires, and a round one called Electrobraid. 600' of black Electrobraid is $110.00 from Tractor Supply.

The round stuff has two strands of copper in an open helix braid woven into a poly sheath that is like a sock woven over a poly rope core. The flat stuff is 3 or four conductor. I would think an antenna like this would be strong, and maybe a little heavy.

The rhetoric for the flat one is it is broad banded, which makes sense.
Dunno about the round stuff, but I expect it might be as well...

I bet the flat stuff should be twisted just like ladder line so it doesnt blow around in the wind.