[Fwd: LF: Multiple Tuned Vertical]

[Andre' Kesteloot]

Väinö Lehtoranta wrote:

> The German Navy VLF antenna at Rhauderfehn (Ramsloh)
> 23.4 kHz is multiple tuned. It comprises eight
> 325.5 metre umbrella top loaded antennas.
> Each antenna is separately fed, and the 8 elements
> of the antenna array are coupled through radiation.
>
> Rr= 1.9 ohm; Rg= 0.15 ohm; Ras= 2.25 ohm; eta= 87%.
>
> 73 from Vaino, OH2LX
>
> At 17:47 28.8.1999 +1200,
> >Rik Strobbe wrote:
> >> But what to do with the 'loss resistance' (RL) in the real world ?
> >> Assume a simple model where both tuned sections share the same
> >> ground-system. In that case RL would be in series with R and this would
> >> mean that a double tuned vertical would not only quadruple the radiation
> >> resistance but also the loss resistance, resulting in an unchanged ratio
> >> between radiation resistance and loss resistance.
> >
> >Bob ZL2CA wrote:>
> >Which is basically what I meant in my previous comments about
> >"transformer action" from the division of current between multiple tuned
> >vertical feeds.  It is similar to a folded dipole transformation.
> >Overall, multiple tuned verticals are still a similar antenna structure
> >from the point of view of "looking back at it from some distance away".
> >Multiple tuned vertical parts are an "impedance transformation trick"
> >but do very little, if anything, for the net radiation resistance of the
> >whole antenna.  Where some advantages are likely is in the multiple
> >grounds.
> >
>
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> V.K.Lehtoranta, OH2LX, POBox 50, FIN-05401 Jokela, Finland
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