K Stability factor

Hi 

I use SP analysis in ADE L and draw the KF (stability factor).

The result is different compared to the K factor derived from any known equations (I got the equations from Pozar's book). i.e. I use for example, the Yij parameters and use my own equations for K.

How I can get more information about how KF in SP analysis is calculated in ADE L ? 

Thanks,

Hamid