RadioBanter - Ground Rod Selection

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Ground Rod Selection

On Sat, 22 Apr 2006 20:43:12 GMT, Telamon
wrote:

In article ,
Monroe wrote:

As a lone time listener but relative newbie to the tech, I've been
educating myself on system basics including ground questions.
Currently using a marginal 1.0 m steel post as a ground for a
shortwave Rx application. Intention is to upgrade to a 8 - 10 ft
ground rod (the only ground off of a 9:1 balun - post ground and balun
bracket - that a coax feedline connects with the Rx; this associated
with an inverted "L" antenna). I've read plenty of references to
copper rod or copper clad ground rods but I've yet to have any local
suppliers recognize this (let alone be able to supply). Standard
availability in my area are galvanized steel ground rods. Are these
of equivalent quality?

Grounds are very important for single wire antennas. They are
unimportant for balanced antennas like dipoles.

If you have a single wire like your inverted L then the ground is
important because it is only half the antenna. The ground is the other
half.

How well the ground rods work depends on the ground conductivity so the
bigger rod may make an improvement or it may not.

A better thing to do other rather than pound in another ground rod
would be to add a ground radial. To test this without much pain attach
a wire to the ground stake with a clamp and run it on top of the ground
underneath your current antenna. Check out the difference it makes on
your reception on several stations on different bands to see if it
makes an improvement.

If the wire laying on the ground makes a significant improvement then
you take the effort to dig a shallow trench and bury it.

The ground wire, even on a single wire antenna, may make little
difference listening wise. I have an inverted L on 20 meters; the
ground makes a huge difference on transmit, bringing down the SWR; but
on receive, I hear no difference whether the ground is attached or
not.

bob
k5qwg

Ground Rod Selection

In article ,
Bob Miller wrote:

On Sat, 22 Apr 2006 20:43:12 GMT, Telamon
wrote:

In article ,
Monroe wrote:

As a lone time listener but relative newbie to the tech, I've been
educating myself on system basics including ground questions.
Currently using a marginal 1.0 m steel post as a ground for a
shortwave Rx application. Intention is to upgrade to a 8 - 10 ft
ground rod (the only ground off of a 9:1 balun - post ground and balun
bracket - that a coax feedline connects with the Rx; this associated
with an inverted "L" antenna). I've read plenty of references to
copper rod or copper clad ground rods but I've yet to have any local
suppliers recognize this (let alone be able to supply). Standard
availability in my area are galvanized steel ground rods. Are these
of equivalent quality?

Grounds are very important for single wire antennas. They are
unimportant for balanced antennas like dipoles.

If you have a single wire like your inverted L then the ground is
important because it is only half the antenna. The ground is the other
half.

How well the ground rods work depends on the ground conductivity so the
bigger rod may make an improvement or it may not.

A better thing to do other rather than pound in another ground rod
would be to add a ground radial. To test this without much pain attach
a wire to the ground stake with a clamp and run it on top of the ground
underneath your current antenna. Check out the difference it makes on
your reception on several stations on different bands to see if it
makes an improvement.

If the wire laying on the ground makes a significant improvement then
you take the effort to dig a shallow trench and bury it.

The ground wire, even on a single wire antenna, may make little
difference listening wise. I have an inverted L on 20 meters; the
ground makes a huge difference on transmit, bringing down the SWR; but
on receive, I hear no difference whether the ground is attached or
not.

I don't know what your situation is so I can't comment on it. I have
done the experimentation and found it makes a huge difference. It could
be that your equipment grounded through the AC mains was enough for
reception. This will be a poor solution in my area due to the fact that
I live in town and the noise level on the AC mains is high.

Basic circuit theory requires that current travels in a loop. No power
flows in an open circuit. People recognize this obvious fact when
considering DC circuits but for some reason it is forgotten when it
comes to RF. The single wire of an Marconi type antenna is half the RF
circuit where ground is the other half. The receiver input is across
the antenna wire and ground.

A Hertzian antenna such as a dipole has two elements that develop the
voltage across the receiver input so an RF ground becomes superfluous.

In any event I proposed a painless way for the OP to test whether a
ground radial will help or not. I don't know what the soil conductivity
is where the OP lives so I can't advise whether another ground rod will
help or not but if an RF ground improvement can be made at the antenna
location over the installed rod then the radial attached to the
installed ground rod will make a significant difference.

--
Telamon
Ventura, California