Message-ID: <001701beeeb6$ea512e80$192097d4@win95.swipnet.se>
From: "Christer Andersson" <sm6pxj@swipnet.se>
To: rsgb_lf_group@blacksheep.org
Subject: LF: SV: Multiple Tuned Vertical
Date: Wed, 25 Aug 1999 07:01:37 +0200
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Thanks for the interest in this issue.

Steve Olney wrote:
> We tend to
>concentrate on radiation resistance alone, when it is the ratio of
>radiation resistance to losses which determines how much goes into ether
>and how much warms up the local environment.

In an article in the Swedish magazine QTC mr Dagaas, chief engineer at SAQ, briefly explains the working principle of the MTA:
A single vertical with top loading and earth system would have a feed impedans of approx. 2,5 ohm.
If six such antennas are parallelled, the total loss resistance becomes 1/6 while the radiation resistance remains unchanged. The total impedance is now 0,45 ohm due to reduced losses.
The antenna input power is fed by 1/6 of the total current (feed impedance is raised by a factor 36).
By varying the current distribution between the verticals (by changing the tuning coils) a suitable feed impedance can be achieved. 20 ohm in the SAQ case.

It seems like the ratio of  Rrad/Rloss is increased. Corresponding thougths can be found in the ARRL Antenna book edition 17 p4-21.

In parallell with this discussion on the LF reflector, the subject has been treated in the news group rec.amateur.radio.antenna.

/Christer