Hmm.. This is hard since you didn't say if you have any other supports
or room for wires.
First, feeding the tower is going to be hard without insulating the
guys. If you add vertical wire antennas close to the tower there is
going to be coupling to the tower, and since the tower has multiple
connections to earth (no radials) there is going to be some loss. But
an antenna with a little loss is a lot better than no antenna at all.
An inverted L, mentioned by K1TTT, would be good for 160 if you have a
support for the top part, and room for radials. Try to keep the end of
the L as high as possible. The more it droops, the lower the radiation
resistance of the antenna, but with 90 feet to work with, it shouldn't
be too bad.
You could also use the tower to support a vertical for 80, but again you
need radials. I would expect the tower to act as a reflector, so put it
facing your favorite direction.
You could hang a sloping dipole for 80 from the top of the tower,
keeping the end at least 10 ft off the ground. I would expect some
reflection from the tower with maximum gain in the direction of the
sloping wire. This antenna should have a lot of vertical component so
it should produce some low angle signals. There will be some ground
loss, but the extra gain may make up for the loss. This might produce a
cardioid pattern covering 180 degrees. Do you have room for two, another
for the other 180 degrees?
You could use a half sloper for 160 from the top of the tower. This will
probably have a little more loss than an antenna insulated from the
tower, but it shouldn't be too bad, and it should produce some low angle
signals. My guess is that is is not going to be very directional.
An inverted vee for 80 should work but it isn't going to produce low
angle signals.
Jerry, K4SAV
Dan H. Gaylord wrote:
>Gentlemen - In my younger days, when dollars were spend on three growing kids
>and hamming was a low priority budget item... I planted a 92' Rohn 25 tower,
>guyed 90 degrees around at three levels. My 50x400 foot lot would not
>support the recommended guying pattern (one set every 120 degrees) and keep
>the beam that I wanted to put up over my own lot/house.
> Taking the cheap route, I did not insulate the guys.
> Dows anyone have a trick to pulling a rabbit out otf the hat & a way to get
> me a good low angle on 160, even 80????? Short of re-guying the whole thing
> (lottsa bucks) and insulating it now, I'm outta ideas...
>73, Dan W7IDG
>_______________________________________________
>
>See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
>Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
>questions and ask for Sherman, W2FLA.
>
>_______________________________________________
>TowerTalk mailing list
>TowerTalk@contesting.com
>http://lists.contesting.com/mailman/listinfo/towertalk
>
>
>
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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