[TowerTalk] Cutting a dipole

[Earl Morse]

Definitely too many variables going on to make the calculation easy and straight forward.  Effects of height above ground, the actual ground parameters, and whether it is in an inverted vee configuration or flat dipole are all going to confound the calculation.  Faster to haul the center up into place with a pulley then measure and snip, measure and snip, until you hit the desired resonance.

The modelling will get you close but you are still going to end up doing the measure and snip on the final product.

Don't snip too far!

GL
Earl
N8SS

Subject: Re: [TowerTalk] Cutting a dipole
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FWIW I have never had good results trying to calculate the difference in resonant freq from low heights vs the desired height on an inverted V.
I finally reached the conclusion it was a waste of time to try and calculate the difference.  
Hoist the center up to its final height and leave a generous amount on the ends and lower and raise each of the ends and keep pruning till you get nirvana.

Bob
K6UJ

From: David Gilbert <xdavid at cis-broadband.com>
To: towertalk at contesting.com
Subject: Re: [TowerTalk] Cutting a dipole
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That's probably because none of us have a true idea just where our 
effective "ground" is.  It's not like there is some high conductivity 
zone in the top few inches of soil, or that everyone's soil conductivity 
profile is at all similar.  I'd bet that in some low conductivity soils 
the effective ground is several meters below the surface, and I'll also 
bet that it is at least to some extent dependent upon the frequency of 
interest.  I use and depend upon EZNEC and HFTA all the time, but I 
don't pretend they are any more accurate than the data I feed them.

Dave  AB7E