🎯 Interactive Smith Chart

What is a Smith Chart?

The Smith Chart is a graphical calculator invented by Phillip H. Smith in 1939. It maps all possible complex impedances onto a circular coordinate system. The center of the chart represents the system impedance (typically 50Ω). The horizontal axis represents pure resistance, the upper half represents inductive reactance, and the lower half represents capacitive reactance.

Every point on the Smith Chart corresponds to a unique complex impedance and a unique reflection coefficient. The constant VSWR circles are concentric circles centered on the chart center. Moving clockwise around the chart corresponds to moving away from the load along a transmission line.

How to Use This Tool

1. Enter your load impedance (R + jX) in the input fields
2. The red dot shows your load position on the chart
3. Add series or shunt components to move toward the center (50Ω)
4. Series L moves up, series C moves down along constant-resistance circles
5. Shunt L moves down, shunt C moves up along constant-conductance circles
6. Transmission lines rotate around the center (clockwise = away from load)

Quick L-Network Matching

For a simple L-network to match a load to 50Ω, try this approach:

• Low R load (<50Ω): Series L first, then shunt C (or shunt L, then series C depending on X)
• High R load (>50Ω): Shunt C first, then series L
• Capacitive load (X < 0): Usually needs series inductance
• Inductive load (X > 0): Usually needs series capacitance

FAQ

Why is the center 50Ω? The Smith Chart is normalized. The center (1.0 + j0) represents the system impedance Z₀, which is conventionally 50Ω for RF systems. The chart works for any Z₀ — just multiply the normalized values.

What does the outer circle represent? The outer circle of the Smith Chart represents infinite magnitude of the reflection coefficient (|Γ| = 1), corresponding to an open circuit, short circuit, or purely reactive load.

Can I save or share a matching solution? Not yet in this version. The URL hash encoding feature is planned for a future update. For now, screenshot the chart or note the component values.