"It Depends"...
It depends on how the steel guys are configured (insulator placement)
etc. A friend had his first insulators 10 ft out on guys 10 down from
his tribander. He reported that the antenna played well on 10 and 20
but sucked on 15M. I suggested his guys looked like 15M directors
10 ft below his DE, focusing radiated energy straight down!
Guys lengths Longer that 1/2 WL will still act as ineffecient reflectors
and are NOT invisible. Such guys will most likely degrade antenna
pattern (F/B and F/S ratios). The only way to get invisible wire guys
is to make each segment less than 0.3 WL on the Highest Band
(11 ft for 10M).
Tom N4KG
On Tue, 25 Jun 2002 David Jordan <wa3gin@erols.com> writes:
> Can someone quantify the value in db in either angle of radiation,
> forward gain or other significant factors when a tri-band beam at
> 100ft
> is retro-fitted from guy wires which are not broken up with
> insulators
> to one using Phillystran? Or put another way. If I had a 100ft
> self-supporting tower with a tri-band beam and compared forward
> gain,
> angle of radiation, etc. it to the same antenna a 100ft tower guyed
> with
> steel cable and no insulators, what would be the most significant,
> i.e.
> noticable difference?
>
> Is this another DXer fanatical .5db at 30 degrees does make a
> significant difference debate?
>
> What am I going to here on my ICOM pro or FT1000D if I don't video
> tape
> the "S" meter movements and play them back for comparison? Am I
> going
> hear a significant difference?
>
> Is this another one of those bigs boys with their big toys and big
> $$
> trying to over engineer an "amateur" antenna installation because
> there
> just isn't much left for them to accomplish in the hobby?
>
> Is this one of those, if I spend $5,000 on Phillystran I'll hear the
> DX
> station 45 seconds sooner than my buddy down the road who is using
> steel guy wires?
>
> Curious minds want to know!!
>
> 73s
> dave
> wa3gin
>
> Guy Olinger, K2AV wrote:
>
> >I've spent as much time as anyone worrying over guy wire
> resonances.
> >
> >The ARRL anti-resonant sections are a myth. They don't work because
> >the guy wires are in the antenna near field and currents are NOT
> >evenly induced across their length by a distant (far field) point
> >source, apparently an unintended assumption in the ARRL figures.
> They
> >further don't work due to capacitive feed across breakup insulators
> >that changes the length in a non-predicted way similar to
> end-effect
> >on dipoles.
> >
> >I'm not sure what construct you mean by transmission line sections.
> >
> >If you can afford it (do the comparative cost math on insulators,
> >grips, etc) get Phillystran. Or maybe do the first 33 feet of every
> >guy off the tower in Phillystran.
> >
> >Sleep at night.
> >
> >73, Guy.
> >
> >----- Original Message -----
> >From: "tongaloa" <tongaloa@alltel.net>
> >To: <towertalk@contesting.com>
> >Sent: Monday, June 24, 2002 2:13 PM
> >Subject: [Towertalk] Guy wire resonance. Break it up or use stubs?
> >
> >
> >>What's the word these days on guy wires.
> >>Break 'em up with insulators or make up transmission line sections
> >>
> >to get
> >
> >>away from
> >>resonance near operating freqs?
> >>Thanks,
> >>-bob
> >>
> >>
> >>_______________________________________________
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> >>Towertalk@contesting.com
> >>http://lists.contesting.com/mailman/listinfo/towertalk
> >>
> >
> >
> >_______________________________________________
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> >http://lists.contesting.com/mailman/listinfo/towertalk
> >
>
>
>
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