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Re: [TowerTalk] Coaxial Moxon

To: Dan Zimmerman N3OX <n3ox@n3ox.net>, <towertalk@contesting.com>
Subject: Re: [TowerTalk] Coaxial Moxon
From: "David J. Sourdis" <hk1kxa@hotmail.com>
Date: Tue, 5 Aug 2008 01:39:26 -0500
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
Thank you Dan, 

Interesting article and it says it all.

David  
HK1KXA
EC5KXA


Date: Sun, 3 Aug 2008 21:07:07 -0400
From: n3ox@n3ox.net
To: hk1kxa@hotmail.com; towertalk@contesting.com
Subject: Re: [TowerTalk] Coaxial Moxon

A quarter wave coax, shorted at the end shows an infinite impedance.Is it 
possible what is described in the link?

A coax just a little bit shorter than a quarter wave shows a VERY quickly 
changing inductive reactance ... so you can change the stub length +/- a few 
centimeters and find the exact value of reactance you need to load the antenna.


But, it's VERY lossy to operate a stub near resonance as a reactance.  I 
estimated something like Q = 1 or Q= 5 for the "quarter wave" (actually a 
little shorter) stubs in that antenna, and a model of it seemed to suggest that 
the gain would be *negative 10dBi* and it would have zero F/B ratio.


You might look at http://www.karinya.net/g3txq/coax_antennas/ as well.

73,
Dan 



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