Topband: Delta Loop

[Bob Eldridge]

>If the vertically polarized delta loop is essentially equivalent to phase
>verticals, than why should it function any better than a phase array of two
>low ground planes with a few elevated radials?

For some reason the loop does not reradiate noise as much as grounded
verticals do. It doesn't function better than a phased array (or indeed as
well) for transmitting, but it is easier to install and adjust isn't it. 

>Seems to me that the vertically polarized delta loop would benefit greatly
>from a conducting ground screen underneath each of the vertical sections 

That's true as long as the ground screen extends many wavelengths away from
the antenna, where the reinforcing reflection occurs. If the screen is right
below the antenna it might reflect some of the radiation straight up.  
The horizontal low wire of the Delta is acting rather like a pair of
end-to-end radials I think, and when George Brown invented the groundplane
antenna it had just two ground plane elements, and he added two more only
because the customer thought they must be necessary.

>If it were up to me, I would consider putting some radials underneath
>the delta loop to improve efficiency.

But the efficiency of a dipole in free space is close to 100%, and this
probably applies to a wire loop. I think you have to be careful about the
relative definitions of efficiency and effectiveness.

The point Bill made that you can open the apex to separate the vertical
elements is worth remembering. This may also help keep the apex away from a
conducting support, which is essential. But don't open the current-reversing
point of the baseline and leave the baseline wires "in line".
I think the ideal "squash" is .4 base line, .3 each slanting wire.

Bob VE7BS