Re: NEC-LIST:NEC--LIST: Smith Chart.

Thank you Ram, I agree.

I, too, would like to stand up in support of Phillip H. Smith's Circular
Transmission Line Chart, a.k.a. the Smith Chart.

Mastering the Smith Chart was to have negotiated the an arcane initiation
ritual into the mysteries of impedance, admittance, and transmission lines.
The bilinear transformation that maps the infinite, unknowable extant of
Cartesian RX coordinates into the self-contained domain of the Smith Chart
is a wonder to behold. And, due homage has been paid to Phillip Smith by
suceeding generations of initiates.

Graphical approaches may have been developed simply as calculational aids.
In a pre-calculator, pre-computer time, complex number calculations were
time-consuming and prone to error. I started out in that era, and can
attest. Graphical techniques were a practical time-saving approach.

But, graphical techniques also embody a context within which to understand.
Smith Charts, Carter Charts, Bode Plots, Nyquist Plots, Nichols Diagrams,
all aid understanding as well as computation.

I am thankful we have the wonderful computational tools we do. One of the
first uses to which I put my Apple II years ago was to do transmission line
calculations. MiniNEC followed shortly after, and I would often run three
Apple IIs on the same problem overnight to get three frequency points. It
was my own early form of parallel processing.

But, don't blow off the Smith Chart. It has a permanent place alongside all
the newer tools we have, and will develop.

Jacob Z. Schanker, P.E.
65 Crandon Way
Rochester, NY 14618

Tel: 585 442 3909
Fax: 585 442 2182
j.schanker_at_ieee.org

----- Original Message -----
From: "Marino, Ron" <ron.marino_at_rfsworld.com>
To: "'Ram Narayanan'" <ram_at_doppler.unl.edu>; "D. B. Miron"
<dbmiron_at_paulbunyan.net>
Cc: "NEC-LIST" <nec-list_at_gweep.ca>
Sent: Wednesday, September 25, 2002 10:22 AM
Subject: 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 While it is indeed true that the Smith Chart has been replaced by modern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
> --
> The NEC-List mailing list <nec-list_at_gweep.ca>
> http://www.gweep.ca/mailman/listinfo.cgi/nec-list
> --
> The NEC-List mailing list <nec-list_at_gweep.ca>
> http://www.gweep.ca/mailman/listinfo.cgi/nec-list
>

-- 
The NEC-List mailing list <nec-list_at_gweep.ca>
http://www.gweep.ca/mailman/listinfo.cgi/nec-list