Use this tool to calculate the load impedance from S11, the input reflection coefficient.

Enter

**Zo**– source characteristic impedance in Ω**S11**– either linear or dB value can be used

The tool will calculate the absolute value of the load impedance **ZL** in ohm.

**Background**

**S11** is the input reflection coefficient with a value between 0 and 1. (Entering values outside this range will result in meaningless output). Referring to the picture of a two port network shown below, **S11 = b1/a1**

If the load impedance is not the same as the characteristic impedance, there will be some reflection. In actual practice, this reflected signal is measured with a network analyzer.

**Formula**

**VSWR = (1+|S11|)/(1-|S11|)**

**Γ = (VSWR – 1)/(VSWR + 1)**

**ZL = Zo*(1+Γ)/(1-Γ)**

**Example Calculations**

For a source impedance of 50 Ω and S11 = -20 dB, the load impedance is calculated to be 61 Ω.