Hi, Jim,
You wrote:
>I want to model some short inductively-loaded verticals and see if they
might be
>used as a directional receiving antenna. I could put three in line atop
a 150-foot
>long chain link fence. This is part of an ongoing struggle to try to
get some
>kind of sensible receiving antenna here.
==========
EZNEC is great for inserting L, C, or R anywhere in an antenna. I'm not
familiar with K6STI's software, but I would think that he allows that
also.
If you're interested in a simple directional receiving antenna, I
developed (from an original idea by EA3VY) what I call the "pennant"
(because of its shape). Its assets are simplicity, good directivity,
broad-bandedness, and small space requirement.
It is pennant-shaped, 14' vertical and 29' horizontal, made of #14 wire.
A 900-ohm termination resistor goes in one end (either the point of the
pennant or the center of the vertical portion) and the feedpoint at the
opposite end. Directivity is in the direction of the fed end, like an
Ewe.
The antenna has about 40 dB F/B on 160, 35 dB on 80 and 30 dB on 40
meters with a cardioid pattern. K6NDV put up two of them back-to-back
with a switching arrangement and says the F/B is extremely good. He
feeds them directly with 50-ohm coax, but a 16:1 balun xfmr would be best
(the input Z is about 900 ohms).
Modeling for the pennant was done with the top of the vertical portion of
the antenna at 20' and the bottom at 6', but it is very "terra-proof".
i.e., there is very little change in its characteristics when its height
is lowered or when the local soil conductivity is changed (unlike the
Ewe!).
I'm preparing to put up a pennant here to verify modeling results.
73, de Earl, K6SE
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