Topband: 5/8 vertical

DAVID CUTHBERT telegrapher9 at gmail.com
Fri Dec 4 08:56:18 PST 2009


If you are asking about a monopole with elevated radials the radials should
be 1/4 wavelength.

If ground mounted with radials on or in the ground the length is not that
important. The feedpoint resistance of a 5/8 wavelength ground mounted
vertical is 200 ohms. The ground loss does not enter that heavily into the
radiation efficiency. A few 50' radials giving a ground loss resistance of
40 ohms costs 1 dB as compared to 120 half wavelength radials.

   Dave WX7G

On Thu, Dec 3, 2009 at 10:41 PM, Bruce <k1fz at myfairpoint.net> wrote:

> Yes, As current radiation is raised in the vertical, longer radials are
> needed.
>
> Horizontal antennas are seldom used on 160 meters and below.  The up to 6db
> ground reflection for horizontals up 1/2 wavelength experienced on higher
> frequencies is attenuated by ground penetration.
> Cave explorers have taken advantage of low frequency ground penetration to
> communicate  via radio with the surface, within limits.
>
> 73
> Bruce-K1FZ
>
>
>  got a question..if using a 5/8 wave vertical should the radials also be
> 5/8
> wave long i guessing yes they do...John K1GUN
>  _______________________________________________
>  160 meters is a serious band, it should be treated with respect. - TF4M
>
> _______________________________________________
> 160 meters is a serious band, it should be treated with respect. - TF4M
>


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