[TowerTalk] 40M wire beam

[T A RUSSELL]

Richard -

Do you have a battery powered  antenna analyzer?
For starters, hang a single inverted vee and determine the length
necessary
for resonance at 7050 (or your favorite frequency).
Hang a reflector that is 5% longer, spaced 20 ft behind the DE.
If you want more elements, hang a director that is 5% shorter,
spaced 20 ft in front of the DE.  No more than 3 elements max .
Use the greatest apex angle you can manage, preferably >120 degrees.
(at 66 ft you are only hurting yourself  by narrowing the pattern in both
planes).

Another option is to use vertically polarized Delta Loops, 
fed 1/4 wavelength down from the apex with an odd number
of quarter wavelengths of 75 ohm cable (RG59 is OK) to
transform the 100 ohm loop impedance to 50 ohms.
If the bottom wire is close to the ground, the loops may
need to be shortened from formula lengths.

73 / GL,  Tom  N4KG
.....................................
On Tue, 25 Nov 1997 15:54:21 "Richard L. King" <k5na@bga.com> writes:
>I would like to try and put up a 40M inverted vee wire yagi between 
>two 66
>foot towers before the CQWW CW Contest. The towers are about 150 feet 
>apart
>so a four or five element yagi is a possibility. This will be a 
>quickie
>experiment to see if I can improve my score just a little bit. 
>
>Can anyone help me out with the dimensions for this antenna? Are there 
>any
>sites that might already have this information available? I don't want 
>to
>go through any long, drawn-out modeling program exercise to accomplish
>this. Besides, I don't have the software. I am willing to keep it 
>simple
>but there isn't much time left to design it.
>
>Thanks.
>
>73, Richard
>
>K5NA@BGA.COM
>http://www.realtime.net/~k5na
>
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