Yuri,

Just once, and I'm done with this.

Someone somewhere along the line mistakenly called it a shield. They
didn't understand how it works and what's important. Get over it.
Look at just the "shield" with no wires inside. Isn't that exactly a
single turn loop antenna? Isn't the feedpoint the gap in the loop?

If you put a wire (or several wires) through the inside of that tube
you used to call the shield, they just pick up the signal from the
feedpoint. Consider a single wire through the tube. There is a
voltage across the gap, the feedpoint of the loop. Since there is
essentially no voltage drop along the wire in the center, across the
distance of the gap in the tube, then the voltage across the gap must
appear as transmission line voltage across the coaxial feedlines which
are made up of the wire and the inner surface of the tube. If you've
arranged things symmetrically, then the total gap voltage will divide
equally between the two. Then it's just standard coaxial lines from
there to where you connect your receiver, or where you put a tuned
tank.

Or if you have multiple wires through the tube, the net transmission
line current divides among them. And you can resonate them with a
capacitor, but that doesn't make them have antenna currents on them.

If you have another way to analyze it accurately, fine. I don't care.
My way works for me, and it does not disagree with the _performance_
I've seen you post about. It does disagree with the _theory_ you've
suggested.

As for WHY adding the "shield" helps get rid of local e-field noise
(from sources less than a few wavelengths away, which at VLF might be
kilometers), and why the nulls are more perfect, it's because symmetry
is CRITICAL for that performance, and adding the outside tube allows
you to make a more perfectly symmetrical loop than you can practically
accomplish with just wires and all the tuning stuff you hang off it.
If you are VERY careful to keep things symmetrical, you can also do it
without the tube. But it takes amazingly little imbalance to screw
things up.

Dat's it in a nutshell.

Cheers,
Tom