Smith Chart

A chart designed for electrical and electronics engineers specializing in radio frequency (RF) engineering to assist in solving problems with transmission lines and matching circuits. The Smith chart is plotted on the complex reflection coefficient plane in two dimensions and is scaled in normalised impedance (the most common), normalised admittance or both, using different colours to distinguish between them.

On the Smith Chart a wave travels down a transmission line of characteristic impedance Z0, terminated at a load with impedance ZL and normalised impedance z=ZL/Z0. There is a signal reflection with coefficient Γ. Each point on the Smith chart simultaneously represents both a value of z (bottom left), and the corresponding value of Γ (bottom right), related by z=(1 + Γ)/(1 − Γ).