Winter Ground System

[W1ITT]

I have a wire Tee antenna, about 85 feet tall with 24 feet on each side that I use on 160 meters. On one side it's bounded by a ledge bottom brook and on the other side by the back lawn.  I have a ground screen across the brook and a few radials under the lawn, but not enough.  After rereading Rob Sherwood's old article on chicken wire grounds I decided to roll out some chicken wire for winter.  I bought this plastic coated stuff because I think the coating will protect the conductivity of the twisted joints better than having it out in the weather.  And it seems easier to handle when unrolling.
  https://www.ebay.com/itm/Chicken-Wire-Fence-BLACK-PVC-Coated-UV-1-Hex-Poultry-Aviary-Bird-Chicken-Wire/282960462982?hash=item41e1c20486:g:xqAAAOSwbsta9Jwb 
  I got the one-foot wide material, but wider would probably be better, depending on the project budget.  Years back, chicken wire was available as "galvanized after weaving" but I haven't been able to find that in years. So called "hardware cloth" is galvanized at all the connections but it costs more than I want to spend.   The plastic coating scrapes off well with a knife and the wire solders OK with a touch of rosin paste flux for connecting wires.
http://sherweng.com/documents/GroundScreen-sm.pdf
The article shows feedpoint measurements with a short vertical, the ones with the lowest R value being the configurations with the lowest ground system losses.  I set the mower deck down close and will pin three chicken radials out for winter and roll them back up next year for lawn mowing season. Next project is to get a DHDL receive antenna up so I can hear well.
73 de Norm W1ITT

[WB4AM]

Hello Norm,

I envy your 85 foot "T" antenna.  When I lived in Pa. I used three aluminum pipes telescoped together.  It started out at 3 or 3.5 inch "OD" and ended
at 1 7/8 "OD" at 58 feet.  I extended the length with a 10 gauge stranded wire out to 105 feet.  At the bottom I fed it with a 1050 Pf air variable capacitor
that was driven with a dc motor that was wired with a center spring DPDT toggle switch to allow the reversal of the motor for easier tuning.

The point that I wanted to bring up, after installing many ground wires I wanted to also add chicken wire.  I found it was a lot of work flatten out the chicken wire
and tying it down to be able to cut the grass.  But the kicker was after just about two years it started to rust badly.  I ended up removing it.  I would not recommend
using chicken wire due to my experience, maybe someone else would have a better experience.

I also installed two above radials.  I had about 45 125 foot ground radials in total.  The antenna worked very well.  The band width was very narrow, but with the air variable
I was able to tune mostly the entire band to 1:1.  I had the antenna cut mostly for the middle to the bottom of the band so when I got up around 1.94 mhz I could only tune
to about 1.5 swr.  But at these frequencies 1.5 swr was nothing to worry about.

I have not had the chance to install this same antenna here in Tn. but I have started the project!

It would be nice to hear how you like using the plastic coated chicken wire.  I have found the more wire you install the better the signal and the swr curve will slowly change
as more wire is installed.

You didn't mention how you constructed the 85 foot section.  I take it you are using a tower to attach the wire.

73
Ken

[W1ITT]

Ken...  I didn't exactly "construct" the 160m Tee.  Along the brook are a couple 100 foot white pines, over 100 feet apart.  I shot a line over the top of each and hauled up a catenary.  On one end, the catenary is made of the top part of the 160m Tee.  Further along I transition to 4000 pound Phillystran which is the boom for an 80m two element wire driven array.
I don't intend to mow over this ground system, as I've been there and had the experience of untangling it from the mower blade.  The reason this is a" winter ground" is because I'm not as serious about 160m as some and I'll only play during the cold months, and will accept diminished capability in the warmer months.  I mowed my grass on the first of October for the last time until about Memorial Day and shortly it will be covered with snow here in Maine, and that will hold it secure.  Again, I'll roll it up in the spring.

By the way, I have used the chicken wire ground screen with good effect for temporary grounds on Beverages also.  A neighbor, W1IMD has a full sized 160m wire quad built around his 280 foot free standing cell tower.  A number of years ago Milt N5IA (sk) came east to use the station in a 160 contest.  He brought three 160m reversible Beverage kits for receiving.  The top of W1IMD's mountain is a rockpile left over from the great glacier 10,000 years back and "ground" is not easy to accomplish.  We went to the feed store and bought chicken wire and used 3 by 20 foot strips as the ground terminations, with excellent directivity indicating that our concept was effective on 160m.  It's probably all rusted now, but all it had to do was last for a week on that project.
73 de Norm W1ITT

[W1ITT]

UPDATE:  In between raindrops this morning I put out the coated chicken wire radials under my 160m Tee.  I had 150 feet of the one-foot wide wire.   I ended up putting out four radials, three about 25 feet long and one about 75 feet long, covering about 180 degrees of grass.  Recall that there's a brook on the other half of the circle.  I cross the brook with a heavy lead and connect into a four foot by 100 foot screen and a few wire radials.  As with most other residential installations, I have to avoid some areas, such as parts of the lawn that get plowed in the winter. 
At the ham shack, my 1.0 to one SWR point went down from 1830 to about 1800 khz.  Tomorrow, when it's not raining, I'll go out with a network analyzer and readjust the base tuning network to bring the minimum up to about 1840 or so.  As things stand now, I go to 2:1 at about 1855 and 3:1 at 1885.  Sharp tuning on a vertical is not all bad as it is indicative of a less lossy ground system.  Is mine now at the optimum point?  I don't know as the best way to find out is to keep throwing ground improvement down, either radial wire or more screen until things stop changing, and I've thrown as much money at it (for now) as I think is worthwhile. The chicken wire that I got likes a bit of paste flux to make it accept solder to attach the pigtails.  I think this is the ground system that has given me the best system improvement in a short amount of time.  I spent about $75 and 90 minutes at it. 
73 de Norm W1ITT

[WB4AM]

Hello Norm,
 
It is my understanding to have an optimum system, one would have to have a complete grounded circular
copper plate out to 125 feet beneath the antenna.  Yea right, imagine that!  Then I hear one would want
to have 125 radials down at 125 feet to make it optimum beneath the antenna.  This would be more possible but
of course it's not always possible.  So the next best thing is to put down as many radials as possible and around
the bottom of the antenna as much as possible.  Someone will always have a better antenna then the next guy,
but as we know it's the experience of experimenting and the efforts that we take to enjoy the out come!
And course everyone's mileage will vary due to everyone's situation and location. 
There is also the above ground radial theory.

When I get involved with installing an antenna, I have always tried to make my system
as good as I can get it, until I get tired and bored to a point where I finally say I'm done!

What I have found out with my vertical with radials over many years the radials will be less affected with
Mother Nature always trying to take everything back.  So one thing I found it is very important to seal
all connections when connecting the radials to the ground rod.   Stranded wire wants to absorb water, where
solid wires are not as flexible and want to break under pressure when riding a riding mover over them even though
they are buried.

I am not sure what my approach will be the next time around when installing radials but I will try to take
an account on trying to prolong them over the years to come.

When I get my 160 meter vertical back up, maybe we can set up a time to get on and see how our signals can do back and forth.

As mentioned I had used coax with a remote variable capacitor to tune the antenna, now I have been thinking of using ladder line with a balance tuner here in the shack.  Not sure what direction I will really take, I am just tossing ideas around for now.

Sounds like your antenna system is working out for you without a lot of money being spent.

If I may ask, what is the most farthest station you have contacted with your vertical?

[W1ITT]

Ken...  I have been involved with a number of "optimum" antenna ground systems in my professional life.  There were a pair of four-tower directional medium wave arrays in the Middle East, each with switchable patterns and all the towers had 120 radials laid on the desert then covered with fist sized broken rock to make it more difficult for the locals to steal the copper at night.  It was number 10 hard drawn, silver soldered at junctions.  The biggest was a new radial system for a 153 khz long wave setup in Romania.  The boys insisted on running a perimeter wire all around at the ends of the radials although it wasn't on the plan.  There's no harm in it but it's entirely unnecessary.  It got them paid for a few more days before they got sent off and they were good fellows so I didn't raise a fuss.
And then I come home to Maine and do, as most hams do, the best I can within a "reasonable" budget out in the back yard.  Yes, lead based solder will decompose outdoors in a few short years, so sealing of connections is the correct thing to do. The non-lead Oatey plumbing solder is available at the local hardware store and not too pricey.   Look at some of the material in ON4UN's book Low Band DXing and you'll see that returns diminish somewhere beyond 32 radials unless you are working with the taxpayers' money.  Our own experience in the field bears this out.
My 160m DXing is casual catch as catch can, mostly CW, haven't tried FT8 yet.  I've worked into the Indian Ocean, real QSO exchange name and rig etc, as well as DXpeditions into the South Atlantic and South Pacific RR 5NN TU stuff.  Also SSB into Europe isn't any real trick from Maine, even here in the rocky foothills away from the coast.
Again, this coated chicken wire seems to give the best bang for the buck.  If I had to go somewhere and get a medium wave station on the air in a big hurry without time to install good radials, I'd be willing to get some farm fencing and go for it and worry about perfection later.  It's plenty good for most of us hams.
73 de Norm W1ITT

[R. Fry SWL]

RE: "It is my understanding to have an optimum system, one would have to have a complete grounded circular copper plate out to 125 feet beneath the antenna.  Yea right, imagine that! ..."

Based on the publications of antenna engineering authorities such as Kraus, Brown, Terman, Balanis, Trainotti, etc...

For a given operating frequency, the radiation efficiency of a vertical monopole driven against a set of wires buried in, or lying directly on the area of Earth within a 1/2WL radius of the base of the vertical monopole depends on three factors:

• the radiation resistance (Rr) of the monopole,
• the ESR of the path to the r-f ground (Rg) — which includes both the set of wires used, and the conductivity of the soil they contact, and
• the ESR of the network (Rm) needed to match the complex Z of the antenna system feedpoint to the Zo of the transmission line connected there from the source (the transmitter).

       System radiation efficiency = Rr / (Rr + Rg + Rm)

The graphic below shows the value of Rg vs. soil conductivity for the defined set of wires buried in soil with a conductivity ranging from 2 mS/m to 30 mS/m (the red line), and the resulting radiation efficiency of that system across that range of conductivities (the green line).

Radiation efficiency for this system is rather low even when Rg is less than 1 Ω, because the 1.52 Ω radiation resistance of the electrically short monopole on this frequency is quite low compared to Rg + Rm.

For contrast, a typical AM broadcast station using a 1/4WL, unloaded vertical monopole with an Rr of 35 Ω, driven against an Rg of 1 Ω with an Rm of 1 Ω has a system radiation efficiency of 35 Ω /37 Ω = 0.946 = 94.6 %.

A good "takeaway" from this graphic is that (regardless of Rr), a rather sparse/short set of wires used in the path to soil of high conductivity can produce an Rg of less than 1 Ω.

IOW, it isn't always necessary to use either a solid copper plate or large numbers of 1/4WL or longer wires in that path in order for it to have a very low value of Rg.

[WB4AM]

Ken...  I have been involved with a number of "optimum" antenna ground systems in my professional life.  There were a pair of four-tower directional medium wave arrays in the Middle East, each with switchable patterns and all the towers had 120 radials laid on the desert then covered with fist sized broken rock to make it more difficult for the locals to steal the copper at night.  It was number 10 hard drawn, silver soldered at junctions.  The biggest was a new radial system for a 153 khz long wave setup in Romania.  The boys insisted on running a perimeter wire all around at the ends of the radials although it wasn't on the plan.  There's no harm in it but it's entirely unnecessary.  It got them paid for a few more days before they got sent off and they were good fellows so I didn't raise a fuss.
And then I come home to Maine and do, as most hams do, the best I can within a "reasonable" budget out in the back yard.  Yes, lead based solder will decompose outdoors in a few short years, so sealing of connections is the correct thing to do. The non-lead Oatey plumbing solder is available at the local hardware store and not too pricey.   Look at some of the material in ON4UN's book Low Band DXing and you'll see that returns diminish somewhere beyond 32 radials unless you are working with the taxpayers' money.  Our own experience in the field bears this out.
My 160m DXing is casual catch as catch can, mostly CW, haven't tried FT8 yet.  I've worked into the Indian Ocean, real QSO exchange name and rig etc, as well as DXpeditions into the South Atlantic and South Pacific RR 5NN TU stuff.  Also SSB into Europe isn't any real trick from Maine, even here in the rocky foothills away from the coast.
Again, this coated chicken wire seems to give the best bang for the buck.  If I had to go somewhere and get a medium wave station on the air in a big hurry without time to install good radials, I'd be willing to get some farm fencing and go for it and worry about perfection later.  It's plenty good for most of us hams.
73 de Norm W1ITT

Hello Norm,

You certainly have had some experience with large antennas and ground radials.

I have read some of ON4UN's books on antennas and such and other authors of the similar experiences.  They're always a good read and they always
bring new ideas to an antenna project.

I will have a look at this coated chicken wire.  Copper wire certainly is not as cheap as $15.00 per 500 feet back when I laid my radials in Pa.

As for getting the wire up and over the trees, in the past I used to climb the trees and throw out the wire through the limbs in the direction needed.

I now put together a spool of 50 lb fishing line to the bottom of a drone.  (See attached pic)  I have made the horizontal section a bit shorter as it made the
drone a little more out of balance then I wanted to work with.  The reason for the horizontal section to begin with, is to keep the fishing line away from
the above propellers when bringing the drone down to the ground.  If the drone is flown backward away from the tree and slowly descending at a particular angle
it helps keeps the line from get caught in the propellers.

[WB4AM]

RE: "It is my understanding to have an optimum system, one would have to have a complete grounded circular copper plate out to 125 feet beneath the antenna.  Yea right, imagine that! ..."

Based on the publications of antenna engineering authorities such as Kraus, Brown, Terman, Balanis, Trainotti, etc...

For a given operating frequency, the radiation efficiency of a vertical monopole driven against a set of wires buried in, or lying directly on the area of Earth within a 1/2WL radius of the base of the vertical monopole depends on three factors:

• the radiation resistance (Rr) of the monopole,
• the ESR of the path to the r-f ground (Rg) — which includes both the set of wires used, and the conductivity of the soil they contact, and
• the ESR of the network (Rm) needed to match the complex Z of the antenna system feedpoint to the Zo of the transmission line connected there from the source (the transmitter).

       System radiation efficiency = Rr / (Rr + Rg + Rm)

The graphic below shows the value of Rg vs. soil conductivity for the defined set of wires buried in soil with a conductivity ranging from 2 mS/m to 30 mS/m (the red line), and the resulting radiation efficiency of that system across that range of conductivities (the green line).

Radiation efficiency for this system is rather low even when Rg is less than 1 Ω, because the 1.52 Ω radiation resistance of the electrically short monopole on this frequency is quite low compared to Rg + Rm.

For contrast, a typical AM broadcast station using a 1/4WL, unloaded vertical monopole with an Rr of 35 Ω, driven against an Rg of 1 Ω with an Rm of 1 Ω has a system radiation efficiency of 35 Ω /37 Ω = 0.946 = 94.6 %.

A good "takeaway" from this graphic is that (regardless of Rr), a rather sparse/short set of wires used in the path to soil of high conductivity can produce an Rg of less than 1 Ω.

IOW, it isn't always necessary to use either a solid copper plate or large numbers of 1/4WL or longer wires in that path in order for it to have a very low value of Rg.

Thanks for the graph.  I have seen this one or one like this years ago.  When I mentioned the circular copper plate for a perfect ground system, I was being more
maybe sarcastic or something of the sort!  The copper plate idea was something I had always heard from someone or read a long time ago.

As Norm had mentioned so to speak, we just work with what we have at hand. 

Although the info from the graph may show that some areas will have better results then other places, I would still install as many ground radials as I could or to the point where I am satisfied or just to cheap to place anymore down.

As we all know all locations aren't created equal with what might be built around us, be it buildings, commercial towers, electrical wires, never a perfect situation.
 
I remember a time when I had a phone patch connected to my two meter station and I was near the city of Philadelphia when I went to activate it.

I was parked in the back behind these building that had about a 70 foot narrow driveway to get back there.  When I brought up my phone patch the signal was
not that good with the buildings surrounding me.  Then all of a sudden the signal was much stronger and louder.  I looked up and there was this tractor and trailer driving very slowly due to the heavy traffic.

As soon as the tractor and trailer continued to pass the driveway the signal went back down again. 
I was quite impress to see the affect this trailer had on the signal as it drove by.  The trailer was toward the front of me and my station was about 50 miles behind me.
The trailer surely was a good reflector and it was about 70 feet in front of me.

Anyway that was a little off the subject but I wanted to show how our surroundings can help us and also it can go against us.  (Of course that was a 2 meter frequency)

Don't get me wrong I understand your point about the different soils, but there are always other factors involved as well, at least when your not out in the middle of no where!
Its very interesting to find that every situation isn't always the same due to different situations, at least from my experiences.

[R. Fry SWL]

... Don't get me wrong I understand your point about the different soils, but there are always other factors involved as well...

That is absolutely true.

But then most often there isn't much that can be done to change soil conductivity around the radius of a vertical monopole, the presence of nearby buildings, and/or the effects of big trucks moving along a nearby freeway.

In the case of soil conductivity though, the graphic gives some useful insight into how radiation efficiency is dependent on the number/length of buried radials over a range of earth conductivities that can exist around the base of a vertical monopole (wherever it is located).

Regardless of the propagation environment downrange from the radiator, the more power that is radiated, the greater the received field strength will be for all sets of propagation conditions.