[Towertalk] Grounds, UFER grounds

[Jim Lux]

When you think about it, a single rod stuck in the ground doesn't provide a very good connection to "ground". The surface area of a 1/2" diameter rod 10 feet long is only about 190 square inches.  A 10x10 inch plate will have 200 square inches.  Granted, due to finite conductivity of the ground, the impedance to a presumed "far field" doesn't scale quite that nicely, but you get the picture.

In most concrete slab/foundation construction, they use a "UFER" ground, which is basically a wire embedded in the somewhat conductive concrete slab.  The slab, of course, has a very large contact area with the surrounding ground.

In practice, too, the DC resistance isn't as important as the RF resistance (in the case of a vertical antenna), or, in the case of lightning protection, the inductance.

Jim
W6RMK