To measure Stability Factor on PNA-X Network Analyzer I use 'kfac(S11,S21,S12,S22)' pre define function but for Stability Measure function does not exist. So I typed in Equation Editor '1+Pow(re(S11),2)-Pow(re(S22),2)-Pow(re(S11*S22-S21*S12),2)' based on formula

b=1+sqr(|a|)-sqr(|d|)-sqr(|a*d-b*c|) but result is not correct.

Please advise.

Dragan.

b=1+sqr(|a|)-sqr(|d|)-sqr(|a*d-b*c|) but result is not correct.

Please advise.

Dragan.

Simple fix: |S11|^2 <> S11*S11, so use mag(S11)*mag(S11): why? If S11=X+JY; S11^2= X^2+j2XY+Y^2; |S11|^2=X^2+Y^2

So your equation should be '1+Pow(mag(S11),2)-Pow(mag(S22),2)-Pow(mag(S11*(S22-S21*S12),2)'