[TowerTalk] Fwd: Grounding of tower

George Dubovsky n4ua.va at gmail.com
Fri May 10 11:58:53 EDT 2013

On Fri, May 10, 2013 at 11:24 AM, Jim Brown <jim at audiosystemsgroup.com>wrote:

> On 5/10/2013 6:34 AM, Jim Lux wrote:
>> So if you're driving 30 rods as part of your antenna farm,
> But we do NOT want a connection to earth as part of TX antenna systems

In the case of a radial system on or just below the surface of the earth,
one or many ground rods connected anywhere to the rf ground system should
not hurt, and in limit cases may help, the radial system. You said it
yourself several lines later: the return current flows in the low
resistance wire and not in the lossy earth - that has been added in
parallel with the (superior) wires. If your radial system is indeed the low
Z return path you hope it is, it will carry the return current. If it's
not, then some portion of the current will be forced through the lossier
earth. That is a result of an inferior ground screen, and the presence of
the ground rods isn't going to make it any worse.

Bang in as many ground rods as you like. They shouldn't affect your
superior ground screen for rf purposes, and they may come into play during
surge events.


geo - n4ua

-- the earth is quite lossy, so RF current flowing in the earth WASTES
> transmitter power.  The function of a radial system is to SHIELD the EM
> field produced by the antenna from the lossy earth, so that return current
> flows in low resistance WIRE rather than the lossy earth.
> We need an earth connection for lightning safety -- the only "antenna
> farm" use for an earth connection is for RX antennas like Beverages, which
> USE the lossy character of the earth.
> 73, Jim K9YC
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