There are two smith charts which you can download. Both are postscript files and can be viewed directly if you have a plug in such as ghostview identified by your web browser. You can print the smith chart directly to a postscript printer from ghostview (or a similar plug in). You can also simply save the postscript file and print it directly to your postscript printer. Both of these have been tested from Mac, PC, and Unix platforms. Nevertheless, if you have any problems with them, please send me email.

Black and white smith chart
Color Admittance/Impedance smith chart

A Little History

An article appeared in the January, 1939 issue of Electronics that changed forever the way radio engineers think about transmission lines. Phil Smith devised an extraordinarily clever circular chart that revealed graphically the complex impedance anywhere along a line. The chart is simply the unit circle of the complex plane representing the generalized reflection coefficient. Overlayed are the contours representing constant real and imaginary line impedances. Thus, the chart can be used to directly determine the normalized line impedance at any position of the transmission line as well as the reflection coeficient. The chart also functioned as a units converter. No math is needed because all quantities are simply determined graphically! There's a marvelous symmetry in it's design as well - everything fits together neatly. So ingenious was his invention that it has been the standard of the industry - for nearly sixty years.

If you're pursuing a career in wireless communications, high speed digital circuit design, antenna design, microwave engineering or other related fields, you need to fully understand transmission lines. Using the Smith chart not only simplifies the solutions of transmission line problems but also is a visual aide that actually helps one to understand the physics of the problem. The chart provides a means to visualize and realize impedance matching and line loss. It also provides a clear understanding of VSWR - a very misunderstood subject, and the cyclical nature of the line impedance. Thus, the Smith chart is far from an outdated tool in this day of the compter age, but rather an invaluable one for understanding and manipulating transmission line systems.