dansawyeror wrote in news:45DFA702.9000204
@comcast.net:

The analyzer also shows the response of an open coax to follow the same
circle at the edge of the chart. Is this accurate? The analyzer does
not
correct for length, is this a result of that?

Dan,

Perhaps a better way to understand a Smith chart as a visualisation tool
is to understand the Smith chart as a problem solving tool.

If you want to follow that path, print of a page or three of Smith chart
and plot solve some typical problems (without the aid of a computer
program), think about what the arcs and lines that you draw mean, and see
if you don't get an understanding of what points on a Smith chart mean.
You will need to find a text book or authoritive web article to walk you
through the process... but if you don't plot points for yourself on a
blank chart, you probably won't learn the principles.

The case you are talking about of the Z of an o/c stub at a range of
frequencies is an easy one to solve with a Smith chart. You plot the Z at
the load end of the stub, you draw the arcs for constant VSWR for each of
the frequencies of interest (the arcs are of different length for each
frequency because they are plotted in electrical length), and you read
off the source end Z.

That describes the mechanics of solving that problem, but it helps to
understand that the points on a Smith chart are the sum of two phasors on
a complex plane, and what they represent. You don't really understand the
Smith chart unless you understand what happens on a transmission line.

Owen