On Tue, 05 Sep 2006 22:52:47 GMT, Owen Duffy wrote:

....
It is true that the reflected wave component is not constant with
displacement for a lossy line. The amplitude of the reflected wave
component decreases exponentially from the load end towards the source
end, and the rate at which it decreases is given by the line's
"matched line loss". The phase of the reflected wave component also
changes with displacement (distance along the line).

The amplitude of the forward wave component decreases exponentially
from the source end towards the load end, and the rate at which it
decreases is given by the line's "matched line loss". The phase of the
forward wave component also changes with displacement.
....
On practical lines at HF and above with practical loads, the SWR
decreases smoothly from the load to the source because of line loss,
the lower the loss, the lower the rate at which SWR falls as you
approach the source.
....

I have plotted theoretical forward and reflected power for a detailed
model of RG58C/U at 100MHz with a severely mismatched load to
illustrate the underlying thing that is being measured by a
reflectometer.

The plots are at http://www.vk1od.net/lost/NN7K.htm .

Comments?

Owen
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