# Calculate VSWR and Return Loss from Zload (or Yload or S11) and Zo

This calculator allows calculation of VSWR from Zload (or Yload or S11) and Zo. Note:

• impedance is a complex quantity, it has real and imaginary parts or magnitude and phase;
• instruments are almost always calibrated for Zo being some nominal real value, is Xo=0 (eg when people speak of a 50Ω instrument, that means 50+j0Ω even if they don't know that); and
• cables with loss almost always have Xo≠0, but for most low loss cables at HF and above, Xo<<Ro.

The results are valid only for linear circuits.

 Inputs: Real /magnitude Imaginary / angle Zo (Ω) Real,Imaginary Yo (S) Real,Imaginary Zload (Ω) Real,Imaginary Yload (S) Real,Imaginary Load S11 (ref Zo) Real,Imaginary Load S11 (ref Zo) ρ,θ(°) Load S11 (ref Zo) ρ(dB),θ(°) Load results: Zl (Ω) Zl' (Ω) Yl (S) Yl' (S) S11 1+S11 r θ (°) Γ 1+Γ pu dB VSWR Return Loss Mismatch Loss 1/(1-|Γ|^2)

The calculator does not do a lot of error checking, if you enter nonsense, it will probably produce nonsense.