The Smith chart reference article from the English Wikipedia on 24-Jul-2004 (provided by Fixed Reference: snapshots of Wikipedia from wikipedia.org)

# Smith chart

Learn about the lives of children in Africa

A impedance Smith chart (with no data plotted)

A Smith chart is a type of graph used in electrical engineering that shows how the complex impedance of a transmission line varies along its length, and simplifies the design of matching networks to match the line to its load. It was invented by Phillip Smith in 1939, while he was working for RCA (although the Japanese engineer Kurakawa invented a similar device one year earlier). The reason for its invention, Smith explained - "From the time I could operate a slide rule, IÒve been interested in graphical representations of mathematical relationships."

The basis for all Smith charts is the following equation:

```is the complex reflection coefficient (also called the one-port scattering parameter s or ).
```
```is the normalized impedance of the load of the line, and is equal to , where:
```