Cecil Moore wrote:
wrote:
Cecil, Don't you mean that when a ground wire is N*1/4 wavelength at
a particular frequency it locates the voltage mininum (current maximum)
at the transmitter, and the voltage maximum well away from the
transmitter.

Nope, Mother Earth dictates the boundary conditions. A well-designed
ground system positions the current maximum point at the ground system,
i.e. minimum impedance to ground.

The voltage maximum point would, therefore, be located at the transmitter,
not a desirable condition. Of course, if you are not actually connected/
coupled to Mother Earth, your milage may vary.
--
73, Cecil http://www.qsl.net/w5dxp

I thought we were talking about 2nd floor, not well designed ground
systems, with the ground NOT connected to earth. But it is the best
you can do. That is where an artifical ground can help by locating
the voltage minimum at the transmitter.
Gary N4AST

wrote:
That is where an artifical ground can help by locating
the voltage minimum at the transmitter.

Yes, that's true. An artifical ground equalizes the voltage
at the ground point AND at the transmitter so both are
voltage minimum (current maximum) points. That's exactly
what an antenna tuner does when feeding a resonant 1/2WL
dipole fed with ladder-line through an antenna tuner. I
hope I didn't misunderstand what you were trying to say.
--
73, Cecil http://www.qsl.net/w5dxp

Cecil Moore wrote:

Irv Finkleman wrote:
Why not run two ground wires in parallel -- one twice as long as the
other? When one is Hi-Z the other will be Lo-Z and vice versa.

That will help on some frequencies but it is akin to trying to
erect a 1/2WL fan dipole for all frequencies - can't be done. Sooner
or later, you will run into a frequency where length #1 is N*1/4WL
and length #2 is (N+1)1/4WL. "It's not nice to fool Mother Nature."
--
73, Cecil http://www.qsl.net/w5dxp

OK then, I'll use 3 wires and take my chances! :-)

Irv
--
--------------------------------------
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--------------------
Irv Finkleman,
Grampa/Ex-Navy/Old Fart/Ham Radio VE6BP
Calgary, Alberta, Canada

In article , Irv Finkleman
wrote:

Cecil Moore wrote:

Irv Finkleman wrote:
Why not run two ground wires in parallel -- one twice as long as the
other? When one is Hi-Z the other will be Lo-Z and vice versa.

That will help on some frequencies but it is akin to trying to
erect a 1/2WL fan dipole for all frequencies - can't be done. Sooner
or later, you will run into a frequency where length #1 is N*1/4WL
and length #2 is (N+1)1/4WL. "It's not nice to fool Mother Nature."
--
73, Cecil http://www.qsl.net/w5dxp

OK then, I'll use 3 wires and take my chances! :-)

Irv

If you are on in a building that has prestressed concrete floors,
and coloums, try using the ReBar in the concrete as your RF Ground.
When I built my house on a concrete slab, before the pour I brought
up a steel strap bonded to the rebar and steel mesh in the radio room.
it was a very effective RF Ground clear down to 500Khz.

Bruce in alaska
--
add a 2 before @