"Robert Lay W9DMK" wrote in message
...
On Thu, 25 Nov 2004 21:11:13 GMT, Richard Clark
wrote:

On Thu, 25 Nov 2004 20:20:32 GMT, (Robert Lay
W9DMK) wrote:

I have embarked on careful measurements of lines severely mismatched
(quarter wave open circuit stubs), and I can find no correlation
between my measurements and the values predicted by the "total loss"
equation. My measurements always show very low losses in comparison to
the model.

Hi Bob,

Looks like our two recent postings about roughly the same topic passed
like ships in the night.

How about the numbers (your data) that leads to your suspicions?

73's
Richard Clark, KB7QHC

The only one that falls immediately to hand is probably a decent
representative example. It is a piece of RG-8/U, also known by its
maker, Columbia, as 9913.

It is 5.334 meters long and is approximately 1/4 wave at 10.6 MHz,
which is where I made the measurement. In its open circuit
configuration, it measures 0.57 + j 0.3 ohms.

I am still struggling with some issues of how to interpret those
results, but two things seem to be clear - 1) the reactive component
is because I was about a degree too long for the frequency of
measurement, or there is enough stray capacitance at the open circuit
to transform into a bit of inductive reactance, and 2) the very low
resistive component doesn't seem to fit any math models that I'm
working with.

What do you think?

Bob, W9DMK, Dahlgren, VA
http://www.qsl.net/w9dmk

the 1/4 wave open end coax looks like a short circuit at the feed point. so
your reading makes perfect sense.