Jerry Martes wrote:
I dont propose that there is any practical reason to build a horizontal
coaxial-sleeve horizontal 1/2 wave dipole for HF.

The practical reason is when it is not practical to
center-feed a dipole. If one is forced to run the
coax feedline very close and parallel to one of the
dipole elements, might as well make the element hollow
and run the coax feedline inside it.

I wonder if that would work for a half-square? Make
one of the vertical sections hollow and run the coax
up the center of that section.

But your post suggests
to me an interesting way to build a fullwave "dipole". Two coaxial-sleeve
1/2 waves, end to end, might provide a method of low impedance feeding a
fullwave long horizontal "dipole". I might even try it at VHF.

There are two types of antennas called "sleeve" antennas.
One has the braid connected to the sleeve where the
1/4WL single center conductor emerges. The other has
the braid connected to the sleeve 1/4WL back down the
feedline from that point to achieve a shorted 1/4WL
stub sleeve.
--
73, Cecil http://www.w5dxp.com