Something else to think about...
In my (limited) experience, if a model changes dramatically for a
small change in length, height, etc., there is probably something
wrong with the model.
Barry, W2UP
On 13 Oct 2005 Joe Giacobello wrote:
> Jerry, I have not followed this thread very closely, but is the
> reduction in gain with galvanized from resistive losses?
>
> 73, Joe
>
> K4SAV wrote:
>
> >An update on the 800 meter long wire performance.
> >
> >Using 17 ga aluminum wire vs 0.5 inch galvanized cable I had first
> >assumed, decreases the gain by about 3.7 dB.
> >
> >The antenna pattern is very sensitive to the exact overall length.
> >Looking at it another way, it is sensitive to frequency change. A
> >frequency change of 50 KHz changes what used to be a peak lobe into a
> > null (looking mostly at the pattern off the end of the wire). For
> >example, off the end of the wire, at 1.8 Mhz and an elevation angle
> >of 10 degrees the gain may be -1 dB. Move to 1.85 MHz and the gain
> >is -13 dB, same angle.
> >
> >The method of feeding the wire also effects the pattern. I assumed
> >end fed with the shield dropping straight down into the salt water.
> >This seems to produce the best pattern I could find.
> >
> >Implementing a vee beam with an 80 degree included angle seems to
> >reduce the pattern into something that is very scrambled and with
> >lower gain.
> >
> >I am normally unsure about simulator performance when wires are close
> >to the ground, but in this case since this is an almost perfect
> >ground, this seems to be within the guideline of the simulator. The
> >simulator shows very little difference between using perfect ground
> >and salt water except between 0 and 3 degrees elevation.
> >
> >Jerry, K4SAV
> >
> >
> >
> >>
> >>
> >>
> >>
> >
> >_______________________________________________
> >
> >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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> >
> >
> >
> _______________________________________________
>
> 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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> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
--
Barry Kutner, W2UP Internet: w2up@mindspring.com
Newtown, PA Frankford Radio Club
_______________________________________________
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
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