THIS thread is about the galvanized wire fence used to enhance a vertical
antenna ground screen. There is a different thread(simply titled 'Wire
Mesh') talking about the welded concrete reinforcement mesh.
David Robbins K1TTT
e-mail: mailto:k1ttt@arrl.net
web: http://www.k1ttt.net
AR-Cluster node: 145.69MHz or telnet://dxc.k1ttt.net
> -----Original Message-----
> From: Roger (K8RI) [mailto:K8RI-on-TowerTalk@tm.net]
> Sent: Monday, January 18, 2010 23:55
> To: Tower and HF antenna construction topics.
> Cc: n4zr@contesting.com
> Subject: Re: [TowerTalk] Speaking of wire mesh...
>
> I think this conversation is covering two types of wire mesh. One is
> the light to medium weight galvanized. The other that is used for
> concrete reinforcement is much heavier, made up of 1/4" rods and welded
> at each cross junction and there is no coating on it. At least that is
> what went into my driveway. There is a lighter version made of 1/8" rod
> as well. Properly installed I don't see why it wouldn't work well in
> the concrete for a tower base. Be it re-rod or heavy mesh it's only
> real purpose is to keep the concrete from breaking. It basically floats
> within the concrete and junctions are usually nothing more than light
> weight steel wire of about #16 in size that serves to hold the separate
> pieces of re-bar in place.
>
> I have one of the old, detailed catalogs with lots of engineering
> information, but as we are getting ready to remodel the den/ham shack I
> only know it's stored in some box, some where in the basement.
>
> IOW I can not vouch that they did or did not refer to the heavy mesh in
> the catalog.
>
> 73
>
> Roger (K8RI)
>
> Wes Attaway (N5WA) wrote:
> > When placed on, or below, dirt galvanized wire rusts away pretty fast
> here
> > in Louisiana. After a year or two I wouldn't want to be depending on it
> for
> > anything important. Using copper wire might seem more expensive, but
> when
> > everything is considered I doubt that it would be.
> >
> > ------------------ Wes Attaway (N5WA) ------------------
> > 1138 Waters Edge Circle - Shreveport, LA 71106
> > 318-797-4972 (office) - 318-393-3289 (cell)
> > Computer Consulting and Forensics
> > -------------- EnCase Certified Examiner ---------------
> >
> >
> > -----Original Message-----
> > From: towertalk-bounces@contesting.com
> > [mailto:towertalk-bounces@contesting.com] On Behalf Of jimlux
> > Sent: Sunday, January 17, 2010 2:13 PM
> > To: Tower and HF antenna construction topics.
> > Cc: n4zr@contesting.com
> > Subject: Re: [TowerTalk] Speaking of wire mesh...
> >
> > K1TTT wrote:
> >
> >> They may not be perfect, but they do help. I use that stuff under my
> 80m
> >> 4-square... even with the radials raised up 10' putting 150' of that
> stuff
> >> under each vertical was still a measurable change to the impedance when
> I
> >> was putting up the first one and testing it. I got it in 100' sections
> >>
> > from
> >
> >> a local fence installer and put 100' out from the center of the 4-
> square
> >>
> > as
> >
> >> far as it went past each vertical, then a 50' piece at 90 degrees to it
> >> crossing at the base of each vertical. A 1/8" galvanized cable clamp
> does
> >>
> > a
> >
> >> good job of clamping without need for matching metals if you use
> >>
> > galvanized
> >
> >> wire, then use a bigger galvanized clamp to attach to the tower rung.
> >>
> >>
> >>
> > The question I would have is whether you'd be better spending money on
> > copper wire for radials than spending it on steel mesh. Obviously, if
> > one has a cheap source for either, than that might push you one way or
> > the other.
> >
> > For tesla coils, which are entirely a near field thing (100-200 kHz),
> > mesh works great, but there, it's because the mesh makes a more uniform
> > electrostatic field.. the advantage is in the field shape more than the
> > loss effects. The mesh is basically one plate of a capacitor.
> >
> > But for antennas, I'm not so sure.
> >
> > However, it occurs to me that this is something that NEC4 can model
> > (albeit tediously), except for the permeability of the wires.
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