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Old November 8th 11, 09:37 PM posted to rec.radio.amateur.antenna
Jeffrey Angus[_2_] Jeffrey Angus[_2_] is offline
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First recorded activity by RadioBanter: Aug 2011
Posts: 47
Default Measuring transmission line characteristics

On 11/8/2011 2:13 PM, John S wrote:
I think I am the confused one. Do I even need to know the transmission
line characteristics if I am going to short the load end and set the
vector voltmeter for a phase reference of 180 degrees?

I am following the HP app note AN-77 and they do not mention a
transmission line. They say to short the load end of the coupler. I need
to get my antenna away from the test setup, so I add the transmission line.


The problem is that these measurements are designed to be made
as close to the instrument as possible. Adding a piece of transmission
line adds loss and phase shift to the measurement.

So unless you know how to work backwards from the measure you get to
what you're really measuring at the far end, you won't really have a
valid answer.

Jeff


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"Everything from Crackers to Coffins"