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To: "Jim Brown" <>
Subject: Re: [TowerTalk] SECOND FLOOR SHACK
From: Bill Turner <>
Date: Thu, 13 Jul 2006 10:05:44 -0700
List-post: <>

On Thu, 13 Jul 2006 09:49:00 -0700, you wrote:

>Here's something else to help you understand what's happening. Go to the 
>ARRL Handbook or Antenna Book, and study the drawings of voltage 
>distribution and current distribution on an antenna. The peaks and nulls in 
>those distributions are established by the boundary conditions of the wire 
>- that is, the current MUST be zero at the end of a wire, and the voltage 
>will be at a maximum. One quarter wave along the wire will be a current 
>maximum and voltage minimum. Another quarter wave, and you'll be back to a 
>voltage max and current min. When you tune the "artifical ground box," you 
>are moving that voltage minimum to your shack by adding XL or XC in series 
>with the "ground" wire. When you tune your antenna tuner, you are adding XL 
>or XC (and changing the impedance ratio) to get the rig to see an impedance 
>close to the 50 ohms it wants to work into. 

------------ REPLY SEPARATOR ------------

I agree with all you say, but you are only considering the impedance
your TX sees. My point is you want your radiated RF up in the air, not
down near the ground, and especially not flowing through dirt. Things
like MFJ's Artificial Ground can help with impedance matching but will
add little or nothing to help your signal compared to a truly
efficient antenna.

Take a look at the top DXers and contesters and see what they do with
their RF. None of it is flowing through ground wires or artificial
grounds and especially not through dirt.

Bill, W6WRT

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