Re: Topband: Adding chicken wire or mesh on top of radial field

[Yuri Blanarovich]

I think the best vertical installations were done by old radio 
engineers. 

No modeling programs, but tedious solid measurements reflecting reality.


What I saw at WOO - Long Lines AT station is perhaps ideal setup for 
vertical all band (discone) antennas.
Radiator sits on concrete base about 3 ft high, with insulator. Tower 
radiator is about 30 ft high, with bundle of wires coming from the top, 
to the ring about 2/3 up, then down back to base.
Not sure if there are any radials/screen at the ground, but the ground 
is practically flooded by the sea water. Sea water comes through dredged 
channels, with evaporation, I presume, increasing the salinity.
Radials are coming out from the base, suspended in the air, over to the 
wooden  circular "fence" (radius about 25 ft?) then they slope and drop 
to the ground.



For better efficiency, it is desirable to make the high current carrying 
portion of the antenna longest possible (electrical closer to 3/8 wave) 
and portion of radials by the base suspended in the air (no earth 
"eating" the RF). If no salt water, looks like the best combination is 
to lay the ground screen in the vicinity of the antenna (gives 
"reflections" for pattern forming) and then suspended or partially 
suspended radials to "counterpoise" the antenna. No need to connect 
screen to radials.
Best 160 inland vertical?  Wally, W8LRL has 3/8 vertical radiator 
sitting on the mound, with 360 radials 3/8 long, laid on the surface.



Looks like WOO Ocean gate QTH is (was) probably the best in the world. I 
never seen the S-meter to sit at 0 on 160m on vertical, dead QUIET!  


Yuri, K3BU.us



On Fri, Oct 19, 2018 at 08:58 PM, Guy Olinger K2AV wrote:

Quite late in response, partly done much earlier. Sometimes I have 
time,

and sometimes I have a house and a spouse.

Peter's original question in this thread was why a radial and mesh mix 
in a

counterpoise should have the radials and mesh bonded together. That is
quite a different question than why mesh at all, or how good is mesh 
by
itself, or mesh versus radials, or just how does "ground" behave at 
the

seashore.


...


BL DID have VERY sensitive thermocouple field strength and power
measuring devices with exceptional accuracy. When I was employed by 
AT
Long Lines in 1963, way back when I still had hair, variants of these 
were
still employed for standard maintenance practices. They were 
significantly

better than anything I myself have owned since. Just BULKY :>))



_
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Re: Topband: Adding chicken wire or mesh on top of radial field

[Phil Duff]

Assuming that copper wire mesh isn’t readily available for the screen that 
leaves galvanized chicken wire mesh fence/netting or perhaps galvanized welded 
wire fencing. 

Would galvainzed welded wire fence be preferable for it’s welded wire joints 
and heavier wire (durability) compared to chicken wire mesh?

Should the existing radials be bonded to the screen at both the outside and 
inside screen perimeters or one or the other?

73 Phil NA4M


> On Oct 19, 2018, at 7:58 PM, Guy Olinger K2AV  wrote:
> 
> Quite late in response, partly done much earlier. Sometimes I have time,
> and sometimes I have a house and a spouse.
> 
> Peter's original question in this thread was why a radial and mesh mix in a
> counterpoise should have the radials and mesh bonded together. That is
> quite a different question than why mesh at all, or how good is mesh by
> itself, or mesh versus radials, or just how does "ground" behave at the
> seashore.
> 
> In the 1937 Brown, Lewis and Epstein (BL) study, field strength was **
> MEASURED ** at one mile at the frequency of 3.0 MHz over 15 times 0.4
> wavelength radials, as well as over 113 times 0.4 wavelength radials, with
> and without a 9 foot square mesh ground screen *over the radials*.  {BL:
> Ground Systems, Proceedings of the IEEE, June, 1937, p. 782}
> 
> Over the 113 radials ZERO change, "with" vs. "without" ground screen,
> relative field strength 1.0 (0 dB)
> 
> Over the 15 radials,
> 
>  "With" the screen:  relative field strength 0.785 (-2.1 dB)
>  "Without" the screen:  relative field strength 0.555 (-5.1 dB)
> 
>   "With" was a *measured* improvement of 3.0 dB over "without", but still
> significantly less than the dense 113 radial field.
> 
> Assuming that the mechanism is the mesh covering loss that would otherwise
> be beneath it...isn't it interesting that over 15 ground radials 3 dB was
> lost in the first 9 feet away from the center of the vertical at the
> ground.
> 
> We should understand the why's of losing 2.1 dB from the dense radials and
> then 3.0 dB more without the screen. Blowing an S-unit would certainly seem
> significant. AND that was 15 times 0.4 wavelength evenly spaced radials,
> not 15 miscellaneous length, shape and position radials.
> 
> In 1937 the only calculation device available for calculation from formulas
> was the slide rule. Computers, running at GHz frequencies solving antenna
> problems with quadrillions of intermediate steps in intricate and advanced
> algorithmic methods, were six decades in the future. As such BL must be
> given credence, as a number of very interesting graphs of RF fields and
> current could not possibly have been anticipated, or "modeled" by any
> process or means available. They HAD to MEASURE to have anything.
> 
> BL were being paid to go through this exercise and had a paid staff for
> assistance, and funds to purchase the best test equipment of the time. They
> could expend the resources to actually measure everything. They overcame
> the obstacles so often defeating our modern personally-funded attempts with
> the deep dollar pockets of the RCA corporation. RCA in turn had a huge
> vested interest in completion of the research, building up commercial AM
> broadcasting.
> 
> BL were explorers in a field mostly still unknown. They have
> extraordinary graphs that put the lie to some corners of today’s thinking
> where models’ approximations have been accepted as fact. We *should* have a
> science of the limits of modeling and issues with “boundary situations”,
> but seemingly do not.
> 
> BL DID have VERY sensitive thermocouple field strength and power
> measuring devices with exceptional accuracy. When I was employed by AT
> Long Lines in 1963, way back when I still had hair, variants of these were
> still employed for standard maintenance practices. They were significantly
> better than anything I myself have owned since. Just BULKY :>))
> 
> Sherwood describes a comparison where *only* mesh screens are used as an
> *alternative* to radials. His study does *not* measure the *interaction* of
> a mesh over radials in any configuration, as queried by the originator of
> this thread.
> 
> Good luck, all and may your 160m wire "smoke 'em" in tomorrow's Pre Stew.
> 
> 73, Guy K2AV
> 
> On Mon, Jun 4, 2018 at 3:24 PM, Grant Saviers  wrote:
> 
>> For simulating a solid conducting plate in NEC with wires, Roy Lewallen
>> (EZNEC author) advises 0.1 wavelength on a side squares of wires.  That
>> would be 16m for topband.  Since adding the mesh is a search for tenths
>> more db's, be conservative and use half his recommendation, 8m or 25'.
>> 
>> If a reasonable radial field of 36 wires x 125' were installed, then
>> pi*D/36 = 21' tip separation (or do the trig for 10 deg angles).  However,
>> buried radials don't need to be 125' long due to the effects of ground,
>> thus the tips will be closer together.
>> 
>> So IMO, based on that guidance, matting at topband wavelengths is not
>> worth it, especially 

Re: Topband: Adding chicken wire or mesh on top of radial field

[Guy Olinger K2AV]

Quite late in response, partly done much earlier. Sometimes I have time,
and sometimes I have a house and a spouse.

Peter's original question in this thread was why a radial and mesh mix in a
counterpoise should have the radials and mesh bonded together. That is
quite a different question than why mesh at all, or how good is mesh by
itself, or mesh versus radials, or just how does "ground" behave at the
seashore.

In the 1937 Brown, Lewis and Epstein (BL) study, field strength was **
MEASURED ** at one mile at the frequency of 3.0 MHz over 15 times 0.4
wavelength radials, as well as over 113 times 0.4 wavelength radials, with
and without a 9 foot square mesh ground screen *over the radials*.  {BL:
Ground Systems, Proceedings of the IEEE, June, 1937, p. 782}

Over the 113 radials ZERO change, "with" vs. "without" ground screen,
relative field strength 1.0 (0 dB)

Over the 15 radials,

  "With" the screen:  relative field strength 0.785 (-2.1 dB)
  "Without" the screen:  relative field strength 0.555 (-5.1 dB)

   "With" was a *measured* improvement of 3.0 dB over "without", but still
significantly less than the dense 113 radial field.

Assuming that the mechanism is the mesh covering loss that would otherwise
be beneath it...isn't it interesting that over 15 ground radials 3 dB was
lost in the first 9 feet away from the center of the vertical at the
ground.

We should understand the why's of losing 2.1 dB from the dense radials and
then 3.0 dB more without the screen. Blowing an S-unit would certainly seem
significant. AND that was 15 times 0.4 wavelength evenly spaced radials,
not 15 miscellaneous length, shape and position radials.

In 1937 the only calculation device available for calculation from formulas
was the slide rule. Computers, running at GHz frequencies solving antenna
problems with quadrillions of intermediate steps in intricate and advanced
algorithmic methods, were six decades in the future. As such BL must be
given credence, as a number of very interesting graphs of RF fields and
current could not possibly have been anticipated, or "modeled" by any
process or means available. They HAD to MEASURE to have anything.

BL were being paid to go through this exercise and had a paid staff for
assistance, and funds to purchase the best test equipment of the time. They
could expend the resources to actually measure everything. They overcame
the obstacles so often defeating our modern personally-funded attempts with
the deep dollar pockets of the RCA corporation. RCA in turn had a huge
vested interest in completion of the research, building up commercial AM
broadcasting.

BL were explorers in a field mostly still unknown. They have
extraordinary graphs that put the lie to some corners of today’s thinking
where models’ approximations have been accepted as fact. We *should* have a
science of the limits of modeling and issues with “boundary situations”,
but seemingly do not.

BL DID have VERY sensitive thermocouple field strength and power
measuring devices with exceptional accuracy. When I was employed by AT
Long Lines in 1963, way back when I still had hair, variants of these were
still employed for standard maintenance practices. They were significantly
better than anything I myself have owned since. Just BULKY :>))

Sherwood describes a comparison where *only* mesh screens are used as an
*alternative* to radials. His study does *not* measure the *interaction* of
a mesh over radials in any configuration, as queried by the originator of
this thread.

Good luck, all and may your 160m wire "smoke 'em" in tomorrow's Pre Stew.

73, Guy K2AV

On Mon, Jun 4, 2018 at 3:24 PM, Grant Saviers  wrote:

> For simulating a solid conducting plate in NEC with wires, Roy Lewallen
> (EZNEC author) advises 0.1 wavelength on a side squares of wires.  That
> would be 16m for topband.  Since adding the mesh is a search for tenths
> more db's, be conservative and use half his recommendation, 8m or 25'.
>
> If a reasonable radial field of 36 wires x 125' were installed, then
> pi*D/36 = 21' tip separation (or do the trig for 10 deg angles).  However,
> buried radials don't need to be 125' long due to the effects of ground,
> thus the tips will be closer together.
>
> So IMO, based on that guidance, matting at topband wavelengths is not
> worth it, especially considering how close together wires are near the base
> of a vertical.
>
> If a research answer is required, with NEC4.2 (EZNEC Pro/4) you can bury a
> mesh in the ground, connect it to the radials, and analyze it.  NEC2 will
> give close answers with radials and the mesh an fraction of an inch above
> ground at a fraction of NEC4 cost.  It would be a real PITA to build the
> wire model for radials and a square mesh since wires have to connect at
> segment junctions.
>
> Grant KZ1W
>
>
> On 6/4/2018 0:04 AM, Raymond Benny wrote:
>
>> Peter:
>>
>> Is this a question or what you are saying is a know fact?
>>
>> I am very interested in this outcome since I will a 

Re: Topband: Adding chicken wire or mesh on top of radial field

[Mark van Wijk]

Some field experiment results from 2016


Location: large farm field

Antenna: Inverted L, using two 21m masts

Note: this theoretically puts Rs at around 18 Ohm



Ground:
- Checken mesh: 6 pieces 8x1m crossed under the TX vertical, which 
offers almost 100% coverage at  8m diameter

- PVC insulated copper-wire  radials, 40 pcs 85ft/25m

Antenna Analyzer: AA-54
After finalizing the antenna Z=28.2 Ohm


Two days later we dismantled the antenna, but performed some 
intermediate measurements.



chicken Mesh + 40 radials   Z= 25.4 Ohm (lower because the inv-L part 
started to sag)


chicken mesh +40 radials(rads all electrically disconnected)  Z=33.4 Ohm

chicken mesh only (radials removed from site)  Z=38.7 Ohm

I can not draw any conclusions from this single setup experiment.


Pictures available at 
https://www.flickr.com/photos/pa5mw/albums/72157663223247069/with/24490646102/



73
Mark, PA5MW


On 6/3/2018 10:14 PM, Peter Bertini wrote:

Why would bonding the added matting be required if it is laid over or
beneath an existing radial field?  It reduces ground losses regardless.

Peter
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Re: Topband: Adding chicken wire or mesh on top of radial field

[GEORGE WALLNER]

The vertical near the sea will benefit from in-phase reflection (which is 
additive) of the vertically polarized radiation. That is probably worth 3 to 
6 dB, depending on the angle, etc. Ground losses, however, will still depend 
on the ground and the ground system. Those losses can be high with a poor 
ground and a poor ground system. If the antenna is electrically short (less 
than 1/4 wave), the losses will be especially high. If the sand is saturated 
with salt-water below, that will sure help, probably because of capacitive 
coupling from the radials.
But nothing will beat standing the antenna in the water and using the 
salt-water (via a low resistance connection) as your ground. Think of it 
like this: if half of your backyard was covered by a copper sheet and the 
other half was just regular dirt, where would you put your vertical? Near or 
right over the copper sheet?


I actually tested the difference between beach and water (unintentionally) 
in the Bahamas. I set up a 62 foot tall vertical standing in about a foot of 
salt-water. The antenna had a aluminum-base whose four legs stuck out about 
10 feet under-water in each direction. The braid of the coax was connected 
directly to the aluminum base. There were no radials. For three nights I was 
getting good reports from EU on 160. Then next morning a storm blew down the 
antenna. I relocated it onto the beach, to about 40 feet from the water's 
edge at high tide. I also added 32 radials, each between 1/8 and 1/4 wave 
long and about 2 feet above the sand. The next few nights I was getting 
comments like "your signal is way down from before". So another three nights 
later, I moved the antenna back into the water (with better guys this time), 
but, again with no radials. Reports indicated that my signal was back to 
"normal". Now, this is purely anecdotal, and I don have any numbers to back 
it. But subsequent DXpeditions bore out my belief that antennas that are 
standing in salt-water perform better than antennas near the salt-water.
Here is another piece of info: Recently, I was testing the new 160 vertical 
for the KH1 DXpedition. It is a 43 foot "fat" vertical with top loading 
wires. I installed it standing in salt-water in the Bahamas (same metal 
base). I measured the feed-point impedance at 9  -120 Ohms. I installed the 
same antenna at my home QTH, where it is standing 4 feet from the water's 
edge and is connected to the sea-water via a 4 foot wide stainless steel 
sheet that goes about 6 foot into the water. Additionally, there are 20 
radials of various lengths on the land side. The antenna measures 12 -120 
Ohms. I believe that the 3 Ohms difference is all in the ground system.
An important point to note: the "return" (braid of the coax) must be 
connected to the sea-water via a low impedance path. Otherwise, there will 
be a loss-making resistance in series with the "return". So the chicken wire 
will help, but it will help more when it is connected.

73,
George,
AA7JV/C6AGU



On Mon, 4 Jun 2018 19:59:57 -0700
 Grant Saviers  wrote:

It is well known by DXpeditioners and an EZNEC analysis demonstrates that 
verticals within 1 wavelength of the sea have greatly enhanced gain at low 
elevation angles in the seaward direction.  There is no need for the antenna to 
be over water for that benefit.  In the opposite direction the pattern is that 
of a vertical over whatever that direction ground properties are.

The conductivity of sea water saturated sand is closer to 1 S/m and seawater is 
usually modeled as 4 S/m.

See my paper "Verticals on the Beach - Some Modeling Results" in QST June 2016 and Al 
Christman K3LC "Verticals by the Sea" series in NCJ 2005.

A conductive plate football field size will reduce ground losses in its direction if connected as "radials". 
It will have essentially no influence on the far field elevation pattern.


Grant KZ1W

snip.

The soil surface conductivity is vey low. If you think about a cooper plate large as a 
football field or salt water, a vertical near it will perform very poor, it only will 
perform well "on it" , connect with the plate and on top of the plate. That's 
way AA7JV vertical antennas works so well, George install them inside the water. Near the 
salt water does not work. Conductivity wet ground (beach) is 0.02, sea water 5. The same 
with radials and mesh wire if you don't connect it, it does not work! 73's N4IS JC

Why would bonding the added matting be required if it is laid over or
beneath an existing radial field?  It reduces ground losses regardless.

Peter
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--
Ray,
N6VR
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Re: Topband: Adding chicken wire or mesh on top of radial field

[Charles Moizeau]

Another choice, and one more durable than the zinc-dipped steel of chicken 
fencing, and probably less expensive than copper mesh, is rabbit/deer fencing. 
This is available in different gauges and different sizes.  It is steel but 
with a thick coating of pvc.  A typical size of its openings is 2" x 4".


73,


Charles, W2SH



From: Topband  on behalf of Rob Atkinson 

Sent: Tuesday, June 5, 2018 9:08 AM
To: topband@contesting.com
Subject: Re: Topband: Adding chicken wire or mesh on top of radial field

for permanent installation it's a waste of time because thin wire
steel mesh (chicken fence mesh) will rust away in most ground in a
short time.

Recommend copper mesh but professionally it only seems to be employed
around the base pier of voltage fed towers.  For a current fed tower a
lot of radials near the feed point, >= 90, is good enough.

73

Rob
K5UJ
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Re: Topband: Adding chicken wire or mesh on top of radial field

[Grant Saviers]

JC,

Have you read the papers I cited?  Looked at numerous reports from 
DXpeditions and several antenna experts re the performance of verticals 
NEAR salt water?


google "vertical antenna near salt water" for a longer list of 
references re a well proven fact.


Grant KZ1W


On 6/5/2018 4:34 AM, n...@n4is.com wrote:

<>

Hi Grant

I don't know how many antennas do you  install, I mean yourself. We all
respect this concept is just wrong.

73's
JC




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Re: Topband: Adding chicken wire or mesh on top of radial field

[Rob Atkinson]

for permanent installation it's a waste of time because thin wire
steel mesh (chicken fence mesh) will rust away in most ground in a
short time.

Recommend copper mesh but professionally it only seems to be employed
around the base pier of voltage fed towers.  For a current fed tower a
lot of radials near the feed point, >= 90, is good enough.

73

Rob
K5UJ
_
Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: Adding chicken wire or mesh on top of radial field

[Grant Saviers]

It is well known by DXpeditioners and an EZNEC analysis demonstrates 
that verticals within 1 wavelength of the sea have greatly enhanced gain 
at low elevation angles in the seaward direction.  There is no need for 
the antenna to be over water for that benefit.  In the opposite 
direction the pattern is that of a vertical over whatever that direction 
ground properties are.


The conductivity of sea water saturated sand is closer to 1 S/m and 
seawater is usually modeled as 4 S/m.


See my paper "Verticals on the Beach - Some Modeling Results" in QST 
June 2016 and Al Christman K3LC "Verticals by the Sea" series in NCJ 2005.


A conductive plate football field size will reduce ground losses in its 
direction if connected as "radials".  It will have essentially no 
influence on the far field elevation pattern.


Grant KZ1W

snip.

The soil surface conductivity is vey low. If you think about a cooper 
plate large as a football field or salt water, a vertical near it will 
perform very poor, it only will perform well "on it" , connect with the 
plate and on top of the plate. That's way AA7JV vertical antennas works 
so well, George install them inside the water. Near the salt water does 
not work. Conductivity wet ground (beach) is 0.02, sea water 5. The same 
with radials and mesh wire if you don't connect it, it does not work! 
73's N4IS JC

Why would bonding the added matting be required if it is laid over or
beneath an existing radial field?  It reduces ground losses regardless.

Peter
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--
Ray,
N6VR
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Topband: Adding chicken wire or mesh on top of radial field

[Craig Clark]

Today's Topics:

   1. Re: Adding chicken wire or mesh on top of radial field
  (Peter Bertini)
   2. Re: Adding chicken wire or mesh on top of radial field
  (Raymond Benny)
   3. Re: Adding chicken wire or mesh on top of radial field
  (n...@n4is.com)


--

Message: 1
Date: Sun, 3 Jun 2018 16:14:45 -0400
From: Peter Bertini 
To: topband@contesting.com
Subject: Re: Topband: Adding chicken wire or mesh on top of radial
field
Message-ID:

Content-Type: text/plain; charset="UTF-8"

Why would bonding the added matting be required if it is laid over or
beneath an existing radial field?  It reduces ground losses regardless.

Peter


All,

Forgive me if this has already been posted. I have not been following TB as
well as I normally do.

http://www.sherweng.com/documents/GroundScreen-sm.pdf

Sherwood's article from HR Magazine.


Craig Clark K1QX

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Re: Topband: Adding chicken wire or mesh on top of radial field

[Grant Saviers]

For simulating a solid conducting plate in NEC with wires, Roy Lewallen 
(EZNEC author) advises 0.1 wavelength on a side squares of wires.  That 
would be 16m for topband.  Since adding the mesh is a search for tenths 
more db's, be conservative and use half his recommendation, 8m or 25'.


If a reasonable radial field of 36 wires x 125' were installed, then  
pi*D/36 = 21' tip separation (or do the trig for 10 deg angles).  
However, buried radials don't need to be 125' long due to the effects of 
ground, thus the tips will be closer together.


So IMO, based on that guidance, matting at topband wavelengths is not 
worth it, especially considering how close together wires are near the 
base of a vertical.


If a research answer is required, with NEC4.2 (EZNEC Pro/4) you can bury 
a mesh in the ground, connect it to the radials, and analyze it.  NEC2 
will give close answers with radials and the mesh an fraction of an inch 
above ground at a fraction of NEC4 cost.  It would be a real PITA to 
build the wire model for radials and a square mesh since wires have to 
connect at segment junctions.


Grant KZ1W

On 6/4/2018 0:04 AM, Raymond Benny wrote:

Peter:

Is this a question or what you are saying is a know fact?

I am very interested in this outcome since I will a installing a TX 4SQ
system where some existing ground radials. Over time, I have heard both
pros and cons on this subject. I would like to read some research or
documentation on this subject.

Tnx,

Ray,
N6VR
Near Prescott, AZ

On Sun, Jun 3, 2018 at 1:14 PM, Peter Bertini 
wrote:


Why would bonding the added matting be required if it is laid over or
beneath an existing radial field?  It reduces ground losses regardless.

Peter
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Re: Topband: Adding chicken wire or mesh on top of radial field

[n4is]

Hi guys


>> Why would bonding the added matting be required if it is laid over or 
>> beneath an existing radial field?  It reduces ground losses regardless

>> I would like to read some research or documentation on this subject.


These are interesting question about ground or should I say "ground" . The
answer for both question is the same. 

First we need to clearly understand what ground means, here some basic
stuff.

# 1- Earth surface 
# 2- Point or place where all points are in the same voltage we refer as
"zero".  

It looks very simple to understand #1, but #2 requires some complex
explanation. 

There is no short answer. 

I will try to make it easy to understand avoiding equations and complex
calculations. This is a ball park estimation. 

Imagine a 2.5m ( 8.2 Ft) conductor. When we pass a current on a conductor
with  no drop in voltage we say zero loss. The voltage on one end is the
same on the other end.  That is true but only for zero Hertz or direct
current DC.  The same 2.5m conductor will behave very different is the
frequency is 28 MHz or 10m. The conductor has a 1/4 wave length and the
voltage at the end will be very high and the current very low, like a 1/4
wave vertical for 10m, the conductor has 10/4 m long.  

Measuring the conductivity of the ground on DC or 60 Hz has nothing to do
with RF. Even the surface conductivity in SIEMENS is frequency dependent and
most of the time referred only as HF.

Why surface conductivity is important, Because it reflects radio waves and
allow propagation to bounce waves between ground and  the ionosphere
reflecting radio waves . Conducting media provide the optimum surfaces for
reflecting radio waves. Metal surfaces, and other conducting areas provide
the best reflections. It is noticeable that for HF ionospheric propagation,
when signals are returned to earth and are reflected back again by the
Earth's surface, areas of good conductivity provide the best reflections.
Desert areas give poor reflected signals, but the sea is much better and the
differences are very noticeable despite the variations in the ionosphere and
overall propagation path.

SURFACE CONDUCTIVITY (SIEMENS)
Dry ground & desert 0.001
Average ground   0.005
Fresh water   0.01
Wet ground0.02
Sea water 5

The interaction of fields and matter, HF and ground, also depends of the
properties of the matter,  permittivity ,permeability, and conductivity.
Part of the wave is reflected, and what is not reflected is reflated though
the matter and it is attenuated. 

When the HF wave reach the ground surface, the field penetrates the ground
surface and the RF keep going down. 

That's why the BOG, or beverage over ground or underground works. Even if
you bury the wire several feet underground it will receive HF signals. On
Very Low Frequencies the waves propagates inside the earth.

On average ground only 10% of the energy is reflected. The other 90%  keep
going reflated inside the soil and attenuated as it propagate down.

The integration between field and matter depends on the polarization too.
Horizontal waves are reflected 180 degree out of phase and vertical is
reflect in phase.

For vertical antennas the reflected signal can be understood using an
imaginary  extension of the vertical antenna inside the ground, like a
vertical dipole with the feed point at the surface. 

Making it simple.

The energy from the feed point is split between the element above ground and
the element below ground. So the energy of the element below ground will be
attenuated.

To avoid that loss we use a "ground plane", the function is to avoid the
energy to penetrate the ground surface and be reflected back increasing the
radiation power. Using several radials close to each other we can reflect
the RF and reduce the loses. The efficiency of the radials depend how close
they are from each other. When the wire is more than wave/100 apart, 1.6 m
for a 160m antenna the energy reflected is very low. There is not
improvement above that distance apart between the radials.

The ground plane can be improved reducing the distance between the wires,
mesh wire does help to increase the reflection. 

Here is the hard part to understand, for RF there is no ground surface on
your back yard. The RF penetrate very deep and the earth can be seen as
translucid matter for RF. 

Burying our cable does not shield it from RF or "ground it", common mode
noise is present even several feet below the surface. If the wires are not
connected to the feed line it is not part of the antenna, if the mesh is not
connected to the feed line it is not part of the antenna as well.  Both the
wires and the mesh are not resonant or 1/2 wave long to reflect the RF by
itself.  1/4 wave elevated radials works because is become resonant adding
the 1/4 wave long vertical part of the antenna. It's not the case for short
radials or mesh wires. If you disconnect the 1/4 elevated 

Re: Topband: Adding chicken wire or mesh on top of radial field

[Raymond Benny]

Peter:

Is this a question or what you are saying is a know fact?

I am very interested in this outcome since I will a installing a TX 4SQ
system where some existing ground radials. Over time, I have heard both
pros and cons on this subject. I would like to read some research or
documentation on this subject.

Tnx,

Ray,
N6VR
Near Prescott, AZ

On Sun, Jun 3, 2018 at 1:14 PM, Peter Bertini 
wrote:

> Why would bonding the added matting be required if it is laid over or
> beneath an existing radial field?  It reduces ground losses regardless.
>
> Peter
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>



-- 
Ray,
N6VR
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Re: Topband: Adding chicken wire or mesh on top of radial field

[Peter Bertini]

Why would bonding the added matting be required if it is laid over or
beneath an existing radial field?  It reduces ground losses regardless.

Peter
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Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: Adding chicken wire or mesh on top of radial field

[Bryon Paul Veal NØAH]

The SWR increase is a good thing as it shows deminishing ground losses exposing 
the true mismatch of the 50 ohm coax to the impedance of the vertical.  So with 
a limited radial field, the mesh seemed to help

My first Inv L back in 1998 with one radial was a flat 1:1 match until W0YG 
explained to be what was going on.  By the time I added 60 1/4 wave radials, I 
was at 4:1 at resonance and used an UnUn to match the coax to the vertical for 
a 1.2:1 match.

Still use the UnUn with my MA160V and MA80/40V .

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From: Topband  on behalf of Eugene Colton 

Sent: Monday, January 29, 2018 10:50:43 AM
To: W0MU Mike Fatchett
Cc: topband@contesting.com
Subject: Re: Topband: Adding chicken wire or mesh on top of radial field

My experience it helped a lot on top of my minimal 160 radial field by
adding much wire square footage to the ground radials.  It might not add
much improvement to a very extensive 160 radial field however.  Expect your
SWR to increase somewhat.
AF9O

On Sat, Jan 27, 2018 at 11:55 AM, W0MU Mike Fatchett  wrote:

> I have some 6ft wide chicken wire I can roll out on top of my existing
> radial field for 160.  Does anyone have an idea what this might do?
>
> W0MU
>
> _
> Topband Reflector Archives - http://www.contesting.com/_topband
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Re: Topband: Adding chicken wire or mesh on top of radial field

[Eugene Colton]

My experience it helped a lot on top of my minimal 160 radial field by
adding much wire square footage to the ground radials.  It might not add
much improvement to a very extensive 160 radial field however.  Expect your
SWR to increase somewhat.
AF9O

On Sat, Jan 27, 2018 at 11:55 AM, W0MU Mike Fatchett  wrote:

> I have some 6ft wide chicken wire I can roll out on top of my existing
> radial field for 160.  Does anyone have an idea what this might do?
>
> W0MU
>
> _
> Topband Reflector Archives - http://www.contesting.com/_topband
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Re: Topband: Adding chicken wire or mesh on top of radial field

[Mike DeChristopher]

Rob Sherwood did some experiments with groundscreen and radials. You can
see his slideshow here: http://slideplayer.com/slide/5717782/

I'm planning something similar at my new QTH but still trying to work out
the mechanical aspects of using screen and radials (bonding etc.).

Mike N1TA


On Jan 29, 2018 9:14 AM, "W0MU Mike Fatchett"  wrote:

I have some 6ft wide chicken wire I can roll out on top of my existing
radial field for 160.  Does anyone have an idea what this might do?

W0MU

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Re: Topband: Adding chicken wire or mesh on top of radial field

[Bryon Paul Veal NØAH]

When I had a 2 acre 80 meter 4 sqr raxial field up in Wyoming, this was 
strongly discouraged due to cancellation of currents, and went with the 
traditional 120 1/4 wave radials using a copper busline to to solder the 
radials in the center so they would not criss cross each other.

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From: Topband  on behalf of W0MU Mike Fatchett 

Sent: Saturday, January 27, 2018 11:55:10 AM
To: topband@contesting.com
Subject: Topband: Adding chicken wire or mesh on top of radial field

I have some 6ft wide chicken wire I can roll out on top of my existing
radial field for 160.  Does anyone have an idea what this might do?

W0MU

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Topband: Adding chicken wire or mesh on top of radial field

[W0MU Mike Fatchett]

I have some 6ft wide chicken wire I can roll out on top of my existing 
radial field for 160.  Does anyone have an idea what this might do?


W0MU

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