The coupling was from the radial field, which ran underneath the metal
fence, not from the vertical conductor. The height of the vertical's
feedpoint, given buried radials running under the fence, would not
have made any difference.
The issue with the fence was that it appeared as a flat metal
conductor of considerable surface area directly over the end of one of
the radial fields. This was in effect a very large capacitive coupling
to a VERY long conductor (the fence).
His ground (sandy loam) is not real high quality, so the fence was a
MUCH more attractive extension to the radial field than the dirt. The
manner of his radial layout tended to sectionalize the radials,
confining the effect mostly to the one near vertical.
It was like having 67 foot buried radials on all of the verticals and
suddenly extending ONE vertical's radials to a 1/4 mile, changing the
resonance of the one vertical, already tuned WITHOUT the fence in
place.
73
----- Original Message -----
From: "j.a.hermans" <j.a.hermans@skynet.be>
To: "Guy Olinger, K2AV" <k2av@contesting.com>; "Gerry Smith"
<w6ter@att.net>; <towertalk@contesting.com>
Sent: Sunday, August 18, 2002 5:55 PM
Subject: Re: [Towertalk] Re: Fence update
>
> ----- Original Message -----
> From: "Guy Olinger, K2AV" <k2av@contesting.com>
> To: "Gerry Smith" <w6ter@att.net>; <towertalk@contesting.com>
> Sent: Sunday, August 18, 2002 9:12 PM
> Subject: Re: [Towertalk] Re: Fence update
>
>
> > He already replaced the close metal fence sections with wood, and
> > broke up nearby metal sections with wood sections. Unbalance
problem
> > at the antennas went away. All antennas tune up equal now.
> >
> > He had one more problem with the inside controller box which was
> > keeping the relays in the coupler box from operating properly.
(Two
> > separate problems.)
> >
> > 73
> > ----- Original Message -----
> > From: "Gerry Smith" <w6ter@att.net>
> > To: <towertalk@contesting.com>
> > Sent: Friday, August 16, 2002 7:28 PM
> > Subject: RE: [Towertalk] Re: Fence update
> >
> >
> > > There are companies that specialize in detuning (broadcast
> > industry).
> > >
> > > Gerry Smith, W6TER
> > >
> > > ------------------------------------
> As I undestood, The aireals where verticals or say Ground Planes. I
just
> wonder what should have happen if he had put the bases of the GP's
at least
> at the same hight as the the goat fence........ Just a practice I
retained
> from mobile radio's on VHF or higher. It surely is something simple
like
> that. Think it over........
> Jos on4kj 73's
>
>
>
>
>
> > > -----Original Message-----
> > > From: towertalk-admin@contesting.com
> > > [mailto:towertalk-admin@contesting.com] On Behalf Of
> > zl1aih@ihug.co.nz
> > > Sent: Friday, August 16, 2002 1:50 PM
> > > To: towertalk@contesting.com
> > > Subject: [Towertalk] Re: Fence update
> > >
> > > Before rebuilding the fence, have you considered detuning the
> > structure
> > > with a linear resonator? Practical examples are discussed in
> > Moxon's
> > > 'HF
> > > Antennas for all Locations' - see page 163
> > > 73 and good luck.
> > > Ken ZL1AIH
> > >
>
______________________________________________________________________
______
> > > 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.
> > > _______________________________________________
> > > Towertalk mailing list
> > > Towertalk@contesting.com
> > > http://lists.contesting.com/mailman/listinfo/towertalk
> > >
> > >
> > > _______________________________________________
> > > 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.
> > > _______________________________________________
> > > Towertalk mailing list
> > > Towertalk@contesting.com
> > > http://lists.contesting.com/mailman/listinfo/towertalk
> > >
> >
> >
> > _______________________________________________
> > 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.
> > _______________________________________________
> > Towertalk mailing list
> > Towertalk@contesting.com
> > http://lists.contesting.com/mailman/listinfo/towertalk
> >
> >
>
>
>
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