I am changing my setup at OAJ Towers to end fed.  For that to work properly you MUST have a good RF return.  Part of that will be my earth rods; 3 in total initially, but I will try to squeeze one or two more in.  They are 8 foot long :)  if you try and hammer them in, you will not manage and it will be a disaster.  I sank two in fairly short order with no hand tools at all; I will post how to do it :D  Even old boys like Gerwyn could manage this method with no grief......  third one goes in tomorrow!


If you are using anything but a balanced antenna, eg, a dipole, you NEED an array of ground, or elevated, radials for your RF return!  ANY radials are better than none, but 120 is considered the commercial/military big installation point of diminishing returns.  For a ham set-up, 32 is good, 16 adequate, 12 OK and 8 workable.  Less than that starts to really go down the slippery slope.  If they are over half the wavelength of your lowest freq it pays dividends by allowing the number of radials to be reduced.  Having at least ONE radial over half lowest wavelength is a real desiderata if attainable; it need not be in a straight line!

Below 8 radials, connection of the centre of the array to a pattern of multiple ground rods bears fruit; 8 rods in a square grid are good. More than 8 in a grid is a diminishing return.  Less rods can be connected together to make smaller arrays, until you get down to 3-in-a- line.  Below 3-in-a-line is slippery slope stuff and not good.  Rods should be about 6 to 8 feet apart.  Elevated radials must never be connected to a ground rod system because it will destroy its performance.

Earth rods NEED to be a minimum of 8 foot long and 12 foot, if sinkable, is better.  A four foot rod is not considered to be properly "coupled" into the earth for RF returns and is marginal.  Similarly, rods are available in 3/8" and 5/8" inch diameters.  The larger diameter rod gives far better results and should be chosen if at all possible; the expense is not all that much more.  All rod joiners should be soldered, by blowlamp, to ensure bonding is maintained as weathering occurs over time.  Salt swamp marsh is the very, very best ground available, but wet Welsh clay is not bad too :)

Having said that, many a ham setup will be a single 3/8" dia, 4 foot rod that was hammered and failed to go in properly; no doubt with a clamp that has corroded.  The singleton rod will be close to the side of the house where the ground is sheltered from the rain and always very dry; and not a single radial will be present!

John

OAJ

Thanks to GW0OAJ for this article


OAJ Towers

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