[TowerTalk] Vertical dipole other choices?

[David Gilbert]

Dielectric loading works as well in theory, but is obviously more 
difficult in practice.  For grins one day I modeled an 80m vertical (fed 
against a couple of radials) with the vertical portion being 3 inch 
diameter PVC with a wire running down the center of it.  By pumping DI 
water (relative dielectric constant about 3.0 if I remember correctly) 
in from the base of the tube I could shift the resonant point over 100 
KHz, thereby making it somewhat tunable.  I shudder to think what it 
would take mechanically to support it, of course, unless I strapped it 
to the side of my tower with all the attendant coupling effects of doing so.

I think people have tried similar things using salt water, except 
without the wire.  I think I even tried modeling that once but found the 
conductive loss was too high ... don't remember for sure.

73,
Dave   AB7E




On 10/20/2020 1:41 PM, jimlux wrote:
>
>
> There are tons of ways to do this - most antenna designs are driven by 
> mechanical constraints not electrical ones.  Just look at all the 
> schemes for loading horizontal dipoles and yagis.
>
> There are people who have built antennas out of conductive liquids.
>
>