Reg:

Dr. Jones was in heavy competition with my father (Mr. Smith), before my
dad developed the "Smith Chart." Darn "Jones Chart" never was any good!
grin

Warmest regards,
John

"Reg Edwards" wrote in message
...
Reg, you've aroused my curiosity on three points:

Why would you use 'Smith Chart' and 'anger' in the same sentence?

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Just a figure of speech. "Anger" suggests setting about a job with
energy, determination and a sense of purpose. As distinct from mere
amusement.
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Why are there any frequencies where the Smith Chart is misleading
and useless?
Which frequencies are they?
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Depending on the size of the errors one is prepared to tolerate and on
the calculated parameter of interest -

Frequencies at which line attenuation per wavelength is not small.
Frequencies at which Zo is not purely real.
Frequencies at which CR is not equal to LG.
Frequencies at which the reflection coefficient is greater than 1.0

Comment : Zo is never purely real. CR is never equal to LG.
And the chart is good only to 2-digit accuracy anyway.

But Walt, you already know all this. Have you ever tried the Jones
Chart? ;o)
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How can you say the Smith Chart is misleading and useless if you've
never used
one, and never inspected one for more than a minute?

Walt, W2DU

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No problem! Worked it out for myself many years ago. Some years ago
I introduced to this newsgroup the excellent book "Transmission Lines"
by Robert A. Chipman, 1968. It aroused some interest. Some of you
obtained a copy.

It has a whole chapter devoted to the Smith Chart and fully describes
its limitations, imperfections, short-comings and approximations.

But the reason Chipman included the chapter was because of the great
savings in labour and time (in HIS day and age) when doing approximate
calculations on short, low loss, HF transmission lines such as antenna
feedlines for which it was designed. Which is all radio amateurs ever
use it for. Hardly any amateurs ever use it in anger. It has other
applications.

I first programmed a computer for work on transmission lines around
1960. At frequencies between 0.1 Hz and 1 MHz, frequencies at which
nobody would dream of using a Smith Chart. So I never became addicted
to it.
----
Reg.