[TowerTalk] Sanity Check: My Grounding Plans

[Bill Turner]

On Tue, 05 Dec 2000 22:45:23 -0500, Byron Peebles wrote:

>I have plans to add an outdoor common ground system to combat RFI
____________________________________________________________

Adding ground wires may or not combat RFI.  You can't really "ground"
RF in the sense you're talking about.  There are two reasons:

1.  The wire leading to the ground rod will itself radiate RF due to
the current flowing through it.  It will act like an antenna even
though you don't intend it to.  Depending on how it is routed, it may
actually make your RFI worse.

2.  For any ground wire to be effective, it has to be very short in
terms of wavelengths.  For example, an eight foot wire is 1/4
wavelength on 10 meters.  If you have a dead short at one end, because
of the standing waves on the wire, you will have a complete open at
the other end - exactly what you don't want.  As a "ground" it would
be completely worthless.

In general, the best way to combat RFI is to prevent the unwanted RF
energy from flowing in the first place, rather than trying to "ground"
it.  Ferrite beads and hipass and/or lowpass filters should be your
first line of defense.  The ARRL book on RFI is highly recommended for
an overview of the subject.  Good luck.

73, Bill W7TI

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