RE: NEC-LIST:NEC--LIST: Smith Chart.

Bravo!!!

-----Original Message-----
From: Ram Narayanan [mailto:ram_at_doppler.unl.edu]
Sent: Wednesday, September 25, 2002 10:16 AM
To: D. B. Miron
Cc: NEC-LIST
Subject: Re: NEC-LIST:NEC--LIST: Smith Chart.

Greetings!

While it is indeed true that the Smith Chart has been replaced by modern
computing tools, it must be borne in mind that the Smith Chart can provide
a wonderful engineering "feel" for impedance matching, which, sad to say,
cannot be obtained using modern gizmos. There is no alternative to
actually looking at how the points lie on a Smith Chart to really
understand impedance matching and have the excitement run inside your
veins and arteries. You cannot get that on a Pentium!

Ram Narayanan

On Wed, 25 Sep 2002, D. B. Miron wrote:

> Good day All,
>
> I am a little surprised at all the traffic on Smith Chart programs.
> Personally, I consider the Smith Chart to be a limiting and obsolete
graphical
> tool, like the slide rule. All the equations being used in the programs
would
> better serve the user if the display were power gain or impedance vs.
> frequency on a rectangular plot.
>
> Exact design equations are available for commonly-used simple networks
such as
> the L-section, T, Pi, short-line equivalents, and the single-stub network.
> These are all easily programmed. Speaking of the single-stub system, the
> usual Smith Chart method, and the textbook equations, assume that the
lines
> involved will have the same wave impedance as the system impedance. This
> isn't necessary, and more compact designs can be found by choosing
different
> wave impedances for the stub and the cascade line. I derived the
equations
> for this case decades ago, when I was first teaching electromagnetics.
More
> complex and broadband matching problems have to be solved by numerical
> methods. Can you see the passband ripple on a Smith Chart?
>
> Doug Miron

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