[TowerTalk] Reverse Fed Towers

[Joe Subich, W4TV]

Most modelling software does not do a good job with reverse fed towers
because the model impedance to ground at the base is much too low and
the model will have too much current in the section of the tower below
the counterpoise.

Place a 100 - 200 Ohm resistor in the bottom segment of the tower model
and start from there with your modeling.

In order to make a reverse fed tower work well, place a cage around the
section below the radials (counterpoise) and tune it to decouple the
tower from ground on your operating frequency.  Alternatively, bond the
radials to the tower and feed the tower above the radials with either a
gamma/omega match or as a folded unipole.

Your goal is to decouple the portion of the tower below the feed point
to keep all the current in the top and radials.

73,

    ... Joe, W4TV


On 12/15/2015 12:45 PM, wosborne44 at gmail.com wrote:
> I have a tower that has a base that is in concrete and grounded.  I
> would like to make it a vertical without installing insulators.   Has
> anyone used elevated radials with reverse feeding, i.e., connecting the
> center conductor to the radials and the shield to the grounded tower?  I
> see this in the ARRL handbook but I cannot seem to make a model of it
> work.  Any help would be welcome.
>
> Thanks,
>
> William Osborne--K5ZQ
>
> 270-205-9565
>
> Wosborne44 at gmail.com
>
>
>
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