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Re: [TowerTalk] Using Stubs to Reject Harmonics

To: <>
Subject: Re: [TowerTalk] Using Stubs to Reject Harmonics
From: "Paul Christensen" <>
Reply-to: "Tower and HF antenna construction topics." <>
Date: Wed, 3 Feb 2010 21:07:45 -0500
List-post: <">>
> "Hi Paul, I think you are confusing impedance and resistance here. There is 
> an infinite number of resistance and reactance combinations that will equal 
> 50 ohms impedance but the only ones with low vswr are the ones at or near 50 
> +j0."

No confusion.  To achieve that 50 +j0 result at the source end of a 1/8-wave 
line still requires a 50 +j0 termination.  However, no matter what is happening 
on the load end of the line and as long as it's resistive only, results in a 
constant impedance of 50-ohms at the source end with a low resistance component 
and wildly varying amounts of reactance between shorted and open extremes.  But 
if (and a big "if") a transmitter's output network could efficiently couple 
into that complex Z seen at the source end of the 1/8-wave line, the result is 
a dummy load with super-high return loss. 

Paul, W9AC 

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