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Message-ID: <3.0.6.32.19990828141830.00823c80@mail.dlc.fi>
Date: Sat, 28 Aug 1999 14:18:30 +0300
To: rsgb_lf_group@blacksheep.org
From: =?iso-8859-1?Q?V=E4in=F6_Lehtoranta?= <vaiski@dlc.fi>
Subject: Re: LF: Multiple Tuned Vertical
In-reply-to: <37C777F5.3441@xtra.co.nz>
References: <3.0.1.16.19990827143645.268f4bda@mail.cc.kuleuven.ac.be>
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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.
>

----------------------------------------------------------
V.K.Lehtoranta, OH2LX, POBox 50, FIN-05401 Jokela, Finland
------ Tel: +358-9-4173965 ---- Fax: +358-9-4173961 ------
E-mail: vaiski@dlc.fi - alias: oh2lx@dlc.fi & oh2lx@sral.fi