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RE: [TowerTalk] RE: [Antennas] coax 'sweet lenght'

To: "'Tom Rauch'" <>
Subject: RE: [TowerTalk] RE: [Antennas] coax 'sweet lenght'
From: "Joe Subich, K4IK" <>
Date: Mon, 11 Oct 2004 11:06:27 -0400
List-post: <>

> Tom Rauch wrote:
> <snip>
> >
> >Move 1/4 wl further to 1/2 wl  and SWR will still remain 1.5
> >but now the impedance is 50 0j ohms.
> >A 50 ohm bridge would show 1:1 but a 75 ohm 1.5:1.

All true ... however, if one is using 75 Ohm cable in a 50 Ohm 
system (e.g., CATV hardline) then the multiple of 1/2 wavelength 
shows a 1:1 SWR on a 50 Ohm bridge - exactly what is desired. 

The 75 Ohm cable is operating with a 1.15:1 SWR and slightly 
higher loss but compared to RG-213 the tradeoff may be worthwhile.  

> >So you see, no matter where you measure SWR it is unchanged
> >unless you have used a different reference meter with the
> >transmission line Z0.

Correct, it depends on the "system" perspective. 


   ... Joe, K4IK 


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