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Re: [TenTec] OT: SWR & Coax

To: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Subject: Re: [TenTec] OT: SWR & Coax
From: Ken Brown <ken.d.brown@hawaiiantel.net>
Reply-to: ken.d.brown@hawaiiantel.net, Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Sun, 06 Jul 2008 22:24:53 -1000
List-post: <tentec@contesting.com">mailto:tentec@contesting.com>
Marinus Loewensteijn wrote:
> When Coax is terminated at the transmitter end and the far end with an 
> impedance that is equal to its defined impedance we will have a SWR of 1:1.
> Only when the currents on inner conductor and on shield are equal and the 
> current / voltage nodes coincide at the same locations then they'll cancel 
> radiation.
> If we have anything else that creates a SWR that is not 1:1 then waves will 
> be reflected from the ends. 
>  Hence no longer will the current and voltage nodes be coinciding. 
> When nodes are no longer coinciding then we will have radiation.
Yes, but they do coincide, even with high SWR.
> What is wrong about this, what am I missing here?
Even when there is a high SWR the current nodes in the two conductors 
occur the same distance from the (mismatched) load.

You can still get radiation due to unbalanced currents, which may be 
caused by non-symmetry of the antenna. Mismatch between the line and 
load, and the high SWR it causes, does not by itself cause radiation 
from coax.


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