SmartSmith for Windows is a Smith Chart program designed to provide a
convenient tool for designing transmission line matching sections. It
can also design matching sections for any electrical circuit in which
it is important to be able to visualize the progress being made while
configuring a particular matching section circuit element.

The program provides for data entry in the form of a complex
impedance in "a + jb" (Cartesian) form that is to be matched to a
purely resistive characteristic impedance as would typically be
encountered in transmission lines. The primary limitation of such an
approach for anything other than transmission lines is that the
characteristic impedance of the line to which we desire a match is
assumed to be purely resistive (no imaginary component).

SmartSmith for Windows provides the user with a suite of nine
different impedance transforming elements that can be used in the
program to implement an impedance match. These nine individually
configurable elements a
• Series Resistance (ohms)
• Shunt Conductance (milli-mhos)
• Series Capacitance (ohms of reactance and pF)
• Shunt Capacitive Susceptance (milli-Siemens )
• Series Inductance (ohms of reactance and uH)
• Shunt Inductive Susceptance (milli-Siemens)
• Open Stub (0 – 90 degrees, any Zo)
• Shorted Stub (90 – 0 degrees, any Zo)
• Series Trans. Line (-180 to 0 to +180 degrees, any Zo)

SmartSmith has many advantages over the paper Smith Chart. Plotting
impedance points on a Smith Chart can be very tedious. Each time a new
value of a design element is to be evaluated, the designer must
generate a new value of reactance in ohms for that element and must
then calculate a new value for the net impedance seen looking into the
circuit with this new value of matching section in place. The designer
then takes those new values of the real and imaginary parts,
normalizes those values and locates the correct coordinates on the
Smith Chart and draws a new point on the chart.

With SmartSmith that process is reduced to clicking the mouse on the
spin control to change the value of that design element and see the
new point being plotted instantaneously. SmartSmith also continuously
shows the complex values of normalized admittance and impedance as the
points are plotted.

In order to progress through the design steps, as a design element is
completed, the designer presses the “Keep and Continue� button in
order to take the latest value of impedance and save that as the new
Load impedance, leaving the plotted points on the Smith Chart. He then
picks the next matching section type and begins configuring that
element to continue the design, as necessary. At any point, the
designer can use the “Discard and Start Over� button to reset the
system to the last “Keep and Continue� values and select a different
type matching section.

The most important feature of SmartSmith is its Wizard. Having entered
the Load impedance into the program, the inexperienced designer may
not have any idea where to begin. By pressing the “What Would the
Wizard Advise� button, the user is taken through a set of simple steps
to transform that impedance to 1 + j0, normalized, and those steps
have been automatically chosen based on the region of the Smith Chart
in which the Load impedance is located.

Download your free copy of SmartSmith version 1.1 using the following
link (slightly larger than 2 MB):

http://www.qsl.net/w9dmk/SWDownloads/SmartSmith11.zip

Or, visit my Web site and peruse all of the free software at:

http://www.qsl.net/w9dmk


Bob, W9DMK, Dahlgren, VA
http://www.qsl.net/w9dmk