[TowerTalk] 80M Delta Loop (bobtail curtain)

[Jim Brown]

On 7/26/2024 8:48 PM, Jim W7RY wrote:
> You guys need to investigate a bobtail curtain.

Thanks for pulling my coat about this one, Jim. Looks like a very useful 
antenna if you want something vertically polarized with a bi-directional 
+/-20 degree beamwidth, and that doesn't need radials! A bit more than 6 
dB gain over a single vertical.

And if you have the space to rig it. It's three quarter-wave verticals 
in-line, spaced a half-wave, with a horizontal wire running between them 
at the top. The three verticals are in-phase, with current minima at the 
base. The outer verticals float from ground. So the beam is broadside to 
the array.

The center vertical is fed against ground, and it's a voltage maximum, 
so feed against ground with a tapped parallel resonant step-up inductor. 
Pretty easy to build and rig if you have the space and the skyhooks to 
hold the horizontal wire at the needed height and in the right places. 
Just drop the three verticals from the wire, with weights on the bottom 
of each.

This antenna would still work well with poor ground, and is that much 
better with good ground!

73, Jim K9YC