I not sure exactly what antenna you are remembering, but there are
several ways of optimizing rectangular loops. Here is one of my
favorites for when you are very limited on height and want a 40 meter DX
antenna. (This could be similar to what you are remembering, or maybe
not.) A 40 meter full wave rectangular loop, oriented vertically,
vertical sides 23 ft, horizontal wires 50 ft, fed in the middle of one
side. This has a couple of nice features. The feedpoint impedance is
50 ohms (nice number), it is a very low angle radiator and beats what
you can do with a dipole in the same height (for DX). Here is a
comparison with the top wire at 40 ft, and a dipole at 40 ft.
El angle Loop Dipole
20 deg 2.4 2.6
15 deg 2.6 0.4
10 deg 1.4 -2.8
5 deg -2.1 -8.5
Because the loop is so squashed, even though it is vertically polarized
it isn't totally omni-directional. In the plane of the loop the gain is
down about 7.3 dB from broadside. The feedpoint impedance varies a
little with height, but you can juggle the length the to width ratios
slightly and get 50 ohms again for whatever height you have. As you
increase the height of these two antennas, the advantage that the loop
has disappears. This works well on 80 meters as well, where height is
more of a problem.
Jerry, K4SAV
jim Jarvis wrote:
>
>Had a couple of comments, both on and off reflector, which made me
>realize that
>I wasn't sufficiently descriptive.
>
>I'm really NOT talking about a standard square loop, regardless of
>whether it's
>organized like a square, or a diamond.
>
>Rather, consider a rectangle, with two horizontal sides spaced
>perhaps 22' apart.
>The lower wire maybe at 15', and the upper one around 40'.
>Horizontal legs were
>something like 85'. My recollection of this is pretty hazy, and at
>the moment it doesn't
>quite foot with the idea of a full wave or two-wavelength loop, and
>it strikes me that it
>should.
>
>The chap in question was in West Virginia or KY, as I recall, and
>had multiple of these
>loops. The notion was that it behaved somewhat like a bobtail
>curtain, producing an
>endfire pattern.
>
>Does that ring a bell for anyone?
>
>n2ea
>
>
>
>
>_____________
>
>
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