Smith Charts for All

I've covered several different programs that are useful when doing electrical engineering in the past. In this article, I want to look at a program called linsmith that helps you do calculations or see how different parameters behave.

Linsmith allows you to generate Smith charts for problems in electrical engineering, especially RF (radio frequency) circuits. Smith charts are a graphical way of representing the rather complex interactions that can happen when dealing with multiple nonlinear electrical components. You can use them to see how they interact and what happens if you vary some of the parameters.

Now, let's look at how to use linsmith to try to make this task a little easier. Throughout this article, I am assuming that you know enough about electrical circuits that I won't need to explain too many of the terms I'm using. If you want to learn more, a good place to start is the Wikipedia page for Smith charts.

First, you will want to install it on your system. It should be in the package management system for your preferred distribution. For example, you can install it on Debian-based distributions with the command:


sudo apt-get install linsmith

Once it's installed, you can start it either by finding it within the menu system for your desktop environment or by running the linsmith command within a terminal window.

This program is strictly a graphical one, so you need to be running X11 in order to use it.

When it first starts, you will see a blank Smith chart, ready for use. On the right-hand side of the main window is a set of tabbed panels where you can enter the details of the electrical problem you are working on. This section is broken into loads that you can apply to the system, a circuit tab where you can define discrete circuit elements that are part of the problem, and a results tab where you can find a running log of the calculations being made.

Figure 1. When you first start linsmith, you will see a blank Smith chart, ready for you to use.

______________________

Joey Bernard has a background in both physics and computer science. This serves him well in his day job as a computational research consultant at the University of New Brunswick. He also teaches computational physics and parallel programming.