The AM Forum

A lot of companies sell them and advertise them for holding plastic ground cover and sod in place, and also for holding down invisible dog fence wire.

One problem with using these is that they are made of galvanised steel.  If you use bare copper wire for radials, one thing you don't want is to allow copper and zinc (galvanising) to come in direct contact in a wet environment like ground soil.

Copper and zinc immersed in a salt or mineral solution forms a simple battery (http://quiz2.chem.arizona.edu/preproom/Demo%20Files/cu-zn_battery.htm) or to be more precise, cell. The galvanic action results in rapid corrosion of the metals.

Besides deterioration of the wire, this may cause rf problems.  I discovered that the hard way years ago when I built an open wire feed line using copper, and used some galvanised steel wire I had on hand to tie the wires to the insulators.  It worked perfectly until the first rain, and then my transmitter wiped out every TV within a quarter-mile radius.  When I inspected the line, I could see corrosion at each joint.  So I took down the line and replaced the steel tie wires with copper and the problem went away.  Every one of those corroded joints acted like a diode rectifier in series with the feed wire.

The lawn and garden supply sod staples should work fine with insulated copper wire.  But for bare copper, I would try to find some scrap copper wire (preferably hard drawn) and make my own.  Copperweld should work ok too.  I have used it for radials, and had no problem with corrosion at the cut ends of the wire.  Broadcast stations are now using lower cost copperweld for radials with the increased price of copper.

If you have an invisible dog, how could you tell if the fence is working.

Sry, couldn't resist. ;D

By whether or not he bites you in the ass.

I use the following counterpoise system for my Inverted-L setup:

plastic Master Gardner Fabric/SOD pins (www.MasterMArk.com) 4.5" long for the far end and charger clips at the base/ground connection for quick discconect for mowing and trimming. I drill a hole in the top of the plastic pins for tying the wire.

The wire is insulated #28 wire stripped from CAT-5 ethernet cable or other available cable. The wire is insulated from the soil or grass over its whole length.

Since the insulation is green and brown and black, only I (and not the neighbors) know where it is.

Phil - AC0OB

It doesn't matter whether radials buried or lying on top of the ground are insulated or bare.  But with #28 wire, the insulation protects the wire from corroding away in the soil.  Bare wire that small wouldn't last long in most soils.

I use these big barb wire staples.  You buy them by the pound from farmers co-op stores.  The prongs are 2 or 3 inches long, not very long but they're FAT and don't bend.  If you have rocks or roots or other junk these hammer in and stay in long enough for the radials to get held down by grass.   they heave up some but not all the way out and I have never had one get flung by my mower however I have my blade set as high as it will go.  When I happen to see one poking up I smack it back down again.  They are probably galvanized but I use insulated wire.  I got sick and tired of those flimsy staples bending on me.

Rob K5UJ

Years ago when I still believed in on ground radials I used whatever #14 or 12 insulated copper wire I could scrounge from the dump. Cut in 8-10" lengths, fold in half, and push into the ground. After a few years the sod grew up and around and completely covered everything including the radials.

Carl
KM1H

So, you lost your "faith" in on-ground radials?  What do you believe in now?

Elevated radials are supposed to be just as effective if not more so, but they are messier to install and maintain.  The only useful purpose in burying radials is to protect them from damage by surface traffic.  Burying them places a layer of lossy earth between the ground plane and the radiating vertical, which is counter-effective to the whole purpose of a radial system, although a few inches of soil over the ground plane is unlikely to have any measurable effect, at least on the lower frequency bands.

Don
You musta seen my posting for sod staples.
Intersting point about bare wire and interaction, and even the corroding staple.
I am using #24 insulated wire for the "new" vertical site.
Of course, I find out about plastic later on in life.

Fred

From all Ive learned from operation and reading everything I could find on them they are fine over excellent ground, so-so over average ground, and positively horrible over poor ground such as my rock pile up here. NH granite is around 6" to 24" deep here and the soil is sandy and rocky with a thin topsoil layer.

Several Internet published FCC proof of performance tests on the BCB show a substantial increase of field strength for elevated radials over a former buried field at the same location for instance. The better sites had to substantially reduce power.

At my old QTH, same town, but down in a hole and partially wet sandy soil I had a 100' tower top loaded with 10-15-20M 4 el yagis. Shunt fed on 160M. At 64 radials I had to wait in line at every pileup and often never got thru. With 128 radials I was in the middle. I then added 6 50' x 4' galvanized, welded and then hot dipped in plastic in a spoke pattern on top of the radials. I started coming out on top in the pileups. We had an active 220/222 mHz simplex group of DXers covering down to RI and the guys always knew when I put down more radials; their comments alone impressed me considerably as these were all top of the Honor Roll operators.

I then tied in the radial field from a pair of 80M 6 wire cage verticals on the other side of the yard. Adjusted the matching network again and was usually kicking ass against the serious QRO guys. Won the ARRL 160M contest in 87 or 88.

At the same time 80M performance took a big jump and I often joined in the grayline brawl on 75 with good results.

After moving here in 89 to the highest location in the area (a fire tower used to be across the street) I decided to not go thru that wire exercise again. I ran 2 sloping wires off the guys at the 160' level, they were slid down the guys about 20'. With 16 radials at about 10' high I could work most DX with a little effort. With 32 radials I was taking no prisoners and quickly got close to 300 countries.

Ive removed that system and in the process of installing 4 telephone poles for a 4 square. The tower had been extended to 180' and the ropes holding the wires will be run from that level and the radials will be around 15-20' high depending on where the rope gets tied off. Running that elevated wire isnt as much a hassle, here at least, as with trying to get them out of the way on the ground since its all woods and no lawn. They will all be running thru the woods and supported from branches. Finding and repairing broken ones will be easy.

My testing was strictly subjective but the results with only 1200W on a serious QRO band speaks for itself. In several years of all band DX contests the 160M score was a good reason we usually won the USA.

To cover different angles and propagation a 160M inverted vee was hung from the 160' level and crossed dipoles, one for 80 and the other for 75, were hung from the same feed point. Won another 160M contest with one rig driving two 2 x 3-500Z amps with one feeding the verticals and the other the Inv V. With the power splitting from the TS-940 the total power was completely legal.

Since I use Beverages on receive, obtaining maximun F/B wasnt a goal and I used the basic 1/4 wave coax lines of old Antenna Manuals and some relays to switch directions or add another phasing section for a figure 8 broadside. F/B in cardioid was around 15dB. Ill start off with just coax again and if it plays well I wont mess with success. The difference in forward gain is only a paper item and not even worth discussing.....the antennas want to work well.

Carl
KM1H