Online Smith Chart Calculator
Online Smith chart: plot impedance, calculate VSWR and return loss, and find ideal L/C matching networks at one frequency. Free, no account.
Free, no account. Your values stay in this browser.
Results · Load
- Normalized impedance z
- 0.5 + j0.5
- Reflection coefficient Γ
- -0.2 + j0.4
- Magnitude |Γ|
- 0.447214
- Phase of Γ
- 116.565°
- VSWR
- 2.61803
- Return loss
- 6.9897 dB
L-network matching
Find ideal components that transform this load to the real reference impedance at the design frequency.
Enter your load and frequency, then choose Auto match to Z₀.
Ideal, lossless components at one frequency. Values are not standard part selections. Parasitics, losses and bandwidth require a circuit simulation.
Reading the chart
A Smith chart maps complex load impedance onto the reflection-coefficient plane. Normalize the load by a positive, real reference impedance: z = Z / Z₀. Constant-resistance circles and constant-reactance arcs locate the load.
Γ = (Z − Z₀) / (Z + Z₀)
VSWR = (1 + |Γ|) / (1 − |Γ|)
RL = −20 log₁₀(|Γ|) dB
VSWR describes the voltage standing-wave ratio. Return loss is positive for a passive, partly reflecting load; it is the negative of S11 magnitude in dB. It is not insertion loss.
Inspect supports passive loads (R ≥ 0) and real Z₀ > 0, including open and short circuits. Auto match additionally requires R > 0 and a positive frequency. Exact matching gives Γ = 0, VSWR = 1 and infinite return loss; phase is undefined. This is a single-frequency ideal model.
L-network matching
Auto match evaluates both L-network orientations, starting at the load. A series element changes reactance; a shunt element changes susceptance. Select a solution to see each calculated step toward the chart center. A zero operation is omitted, so some loads need only one element.
For Z = 25 + j25 Ω and Z₀ = 50 Ω: z = 0.5 + j0.5, Γ = −0.2 + j0.4, |Γ| ≈ 0.4472, phase ≈ 116.565°, VSWR ≈ 2.618 and return loss ≈ 6.990 dB.
From one load to a circuit
Simulate and tune a complete RF circuit in Tersa on iPhone and iPad, or open the separate Web CAD workspace. Calculator values are not transferred automatically.