Re: [TowerTalk] [Bulk] Re: Radials how deep is too deep?

[Grant Saviers <grants2@pacbell.net>]

The K3LC article may yield some help re how to deploy the remaining 
1500' of wire.
Re question #3, Rudy Severns did some analysis and experimental work re 
skin depth in soils, see several articles at antennasbyn6lf.com
A simplistic summary is that below 10MHz, skin depth is a few meters.  
Since the field strength decays with depth, it seem to me that radials 
buried  "several inches" will be only slightly less effective than on 
the surface.
IMO, connecting radials to the rebar in concrete slabs and foundations 
is a good thing.  At least you have a very good Ufer ground for 
lightning and AC line.
The conductivity of concrete varies widely with moisture content, I 
think there is an earlier post that has some values.  For RF 
conductivity of concrete, it is a bit of a challenge to find data, but 
with rebar or mesh it likely much better than soil.  At the least, with 
dry concrete you have dry poor soil with embedded radials.
If you can run the wires so that you can measure the RF currents, then 
you will have some real data on what is working, and what pattern might 
result.
Grant KZ1W


On 12/8/2015 7:11 AM, Drax Felton wrote:
> http://ncjweb.com/bonus-content/k3lcmaxgainradials.pdf
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> Sent from Outlook
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> On Mon, Dec 7, 2015 at 10:29 AM -0800, "John V" <vjohnv@cox.net> wrote:
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> Greetings all.
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> We are in the process of doing a major remodel on our 50' X 117' city lot
> and our house fills the front 40% of the lot. On the back of the lot a new
> 500 Sf garage and 600 Sf RV pad have been built, both sides of the lot now
> have large retaining walls. I have run individual wires to all of the rebar
> used in the foundations and in many cases run radials under where the slabs
> were poured. I am also running in ground radials in any locations where
> there is no concrete or rebar but most of my yard is now house, garage, slab
> and retaining walls.   Many of the radials that are not run under the
> concrete or to rebar are now covered with as much as 6" of compacted dirt
> and decomposed granite. As time allows I continue to add more radials in the
> areas that have soil.
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> I'd guess that I have used about 1500' of wire for the radials in the
> project and have another 1500' of salvaged wire to use. Needless to say the
> lengths are random somewhere between 50' and 80' .
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> #1, have I wasted a bunch of good copper wire by running "radials" under the
> slabs.
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> #2. Have I wasted more copper wire by attaching some of my runs to the rebar
> in the retaining wall foundations, slabs, and foundations?   (we don't get
> much lighting here)
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> #3. How deep in the soil can a radial be and still operate properly, how
> deep is too deep?
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> I guess that my saving grace is that all of the radials are individual runs
> and could be added or subtracted from the field for testing. The goal for
> the radials would be to use them with lowband inverted "L"s  or even a shunt
> fed tower some day.
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> Thanks in advance, John NA6L
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