User Guide
This guide explains how to use the Smith Chart tool on tosmithchart.com.
1. Basic Concept
The Smith Chart visualizes the complex reflection coefficient (Γ) on a unit circle.
When you input impedance values (R, X), the tool internally normalizes them by the selected
characteristic impedance Z₀ and converts them to Γ.
2. Input Modes
Unified r, x Input
Use this mode when your data is organized as pairs of values.
25 10
50 5
75 -10
5 20
10 -30
Blank lines separate data sets.
Separated r and x Input
Use this mode if resistance and reactance are stored separately. Each blank line still defines a new data set.
3. Data Sets
Each set is drawn as an independent trajectory. You can:
- Select which set to display
- Rename each set
- Change the color for clarity
4. Chart Controls
| Option | Description |
|---|---|
| Z₀ | Characteristic impedance used for normalization (typically 50 Ω) |
| Smith grid | Shows constant-resistance circles |
| Admit grid | Shows admittance grid (useful for matching) |
| Arrow | Shows the direction of the last segment |
| Value | Displays normalized (r, x) values near points |
| Marker | Shows discrete data points |
5. Output Table
The table below the input shows calculated quantities:
- |Γ|: Magnitude of reflection coefficient
- VSWR: Voltage Standing Wave Ratio
- Return Loss: −20·log₁₀(|Γ|) [dB]
6. Zoom & Export
- Use mouse wheel or box zoom to inspect regions of interest
- Use Copy PNG to export a high-resolution image
7. Typical Use Cases
- Visualizing impedance trajectories during tuning
- Comparing before/after matching conditions
- Educational demonstrations of transmission line behavior
8. Notes & Tips
- Always verify the reference plane of your measurement data.
- Near |Γ| = 1, VSWR becomes very large or infinite.
- For publications, cross-check with calibrated VNA data.