Hello Tom!

Since you're making the loop small compared with a wavelength anyway,
just how does it matter? I would think the difference in feedpoint
impedance (the gap) between jacketed and unjacketed line would be very
small indeed.

I was just trying to follow the mantra of trying to enclose as much area
as possible. I found that in the end it wasn't as critical as I
thought, ie changing a 10-foot circumference loop to 7-feet. As long as
I could get my tuner to handle it, it seemed that the Q of the circuit
made up for the small difference in the loss of the capture area. So in
the end, you are right, the difference in feedpoint impedance wasn't too
critical.

So one way to make the loop, assuming the gap is at the top, is to
make one side out of coax (which becomes the feedline) and the other
side out of solid rod the same OD as the feedline. Attach the center

snip
Yup! Once I had accepted the fact that the shield is the antenna, all
the other loops I made with one half of the loop being solid wire,
shorted coax pieces, cross-connects etc, all made sense. They all
worked nearly the same except for some very slight inbalances in the
directional pattern, and some small differences in the depth of the
nulls. The light bulb turned on in my head, and now I could stop
cutting up so much coax. grin

Remember, too, that the current is there (in a receiving antenna)
because we put a load across the gap by means of the coax feedline.
Otherwise, any current would only be there to charge the capacitance
of the gap (to a voltage corresponding to the EMF given by Faraday's
law, less a tiny I*R drop in the conductor).

Aha! As in putting say a gapped director or reflector element built out
of copper tubing in front or behind of my coax-built rx loop. Now that
would be interesting, although most likely a mechanical nightmare.

Good info!

73
Brian