[TowerTalk] Speaking of wire mesh...

[Roger (K8RI)]

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 at contesting.com
> [mailto:towertalk-bounces at contesting.com] On Behalf Of jimlux
> Sent: Sunday, January 17, 2010 2:13 PM
> To: Tower and HF antenna construction topics.
> Cc: n4zr at 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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