The question defies simple answers. It's model fodder if ever there
was any. Ask anyone who has tried to design a setup like your question
and then make it work. The tower is always a big unknown.
And unless you have an accurate model of what's on the tower, and the
grounding, even the model is a crap shoot. The interaction is really
complex.
"Detuning", depending on what you are doing, may not actually work for
something in the near field, or closely coupled. All that "detuning"
on the tower may do is change the feed impedance of the inv L, and the
model may show just as much current on the tower with the detuning
measures as without. And "detuning" may detract from the overall
performance, or it may improve it. It just depends.
Closely coupled conductors do not have to be resonant to carry large
currents.
----- Original Message -----
From: "Henrik Weiss" <ozling@mail.dk>
To: "Towertalk@Contesting. Com" <towertalk@contesting.com>
Sent: Tuesday, August 06, 2002 4:59 PM
Subject: SV: [Towertalk] Interaction of Verticals
> Another question related to the topic which is of actuality to me
right now
> is HOW MUCH would one need to detune a tower from for instance a
Inv. L for
> 160 M. that is supported by the same.
>
> If the tower itself is very close to resonance on the operating
frequency is
> 100 Kc detuning then enough ? and how can one measure the L antennas
degree
> of interaction with the tower other than to see no change on the
feedpoint
> impedance ?
>
> Henrik
> OZ1ING
>
> -----Oprindelig meddelelse-----
> Fra: towertalk-admin@contesting.com
> [mailto:towertalk-admin@contesting.com]På; vegne af RCARIELLO
> Sendt: 6. august 2002 21:07
> Til: towertalk@contesting.com; mwdink@eskimo.com
> Emne: Re: [Towertalk] Interaction of Verticals
>
>
> Dink,
> Why bother putting up two antennas?
> Put up the full size 1/4 wave vertical for 80 meters. Then use it as
a base
> feed 1/2 wave vertical for 40 meters.
>
> Rich AA2MF
>
> ----- Original Message -----
> From: <mwdink@eskimo.com>
> To: <towertalk@contesting.com>
> Sent: Tuesday, August 06, 2002 6:33 PM
> Subject: [Towertalk] Interaction of Verticals
>
>
> > Hello All
> >
> > I am looking at putting up two verticals as spare antennas
> > on the 40m and 80m. These are meant to be something for
> > use in SO2R, a multiplier radio, or just another choice
> > in a growing antenna menu.
> >
> > What's the feeling on how close I can mount two separate
> > verticals without interaction? These would probably be
> > full size 1/4 wave antenna's and I hope to be able to
> > put 18-24 inches between them. Only one would be used at a
> > time.
> >
> > If there is a problem with interaction, what if detune
> > the vertical not being used?
> >
> > 73
> > dink
> >
> >
> >
> >
> >
> > _______________________________________________
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>
> _______________________________________________
> Self Supporting Towers, Wireless Weather Stations, see web site:
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> Call 888-333-9041 to place your order, mention you saw this ad and
take an
> additional 5 percent off
> any weather station price.
> _______________________________________________
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>
>
> _______________________________________________
> Self Supporting Towers, Wireless Weather Stations, see web site:
http://www.mscomputer.com
> Call 888-333-9041 to place your order, mention you saw this ad and
take an additional 5 percent off
> any weather station price.
> _______________________________________________
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>
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