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Re: [TowerTalk] Elevated vertical

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Subject: Re: [TowerTalk] Elevated vertical
From: "Paul Christensen" <>
Date: Sun, 25 Dec 2011 21:38:22 -0500
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> If the antenna is 50 ohms X= 0 then regardless of line length
> the it should show 50 ohms at any length.

Yes, if the characteristic Z of the line is 50 ohms.  Not true for lines of 
other characteristic Z terminated into that antenna.

> Only with a reactive load should a line make the impedance different at 
> the source.

True when a non-reactive load value equals the characteristic Z value of the 
line.  How about an antenna feed-point of 100+j0 (non-reactive) connected to 
a quarter-wave of loss-less line with a characteristic Z of 50-ohms?  In 
that case, the line input Z is 25+j0 (i.e., one-quarter of the antenna Z). 
Add another quarter-wave of line (half-wave total) and we'll have 100+j0 at 
the line input -- the same Z as the antenna input.

Paul, W9AC 


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