Using a balanced amp as I do, the loop is not a direct short to ground at DC. The shield of the feedline is not involved in the loop itself. What confused me was in the Mobius design where the feedline is indeed shorted to the center conductor, which is fine until you also connect it to the feedline shield. Everett cleared that up nicely with his diagram he sent me.
I understand that many antenna designs use matching transformers and such that provide a direct DC path to ground but at RF it not a problem. Not so with a 3 foot diameter loop at VLF or even at 30 Mhz.
All good stuff. Great group here.
--- In firstname.lastname@example.org, Andy <ai.egrps@...> wrote:
> > ... but if I ground the shield it becomes a dead short to the feedline coax.
> It is no more than a dead short, than a loop antenna is a short on the
> feedline. And yet we know loop antennas work. The "short" is only at DC.
> Think of it as a balanced loop antenna where the center-tap of the
> loop is grounded.