Dan Dvorscak
Ansys Employee

I would still re-normalize any ports on the PDN to 0.1 or 1 Ohm. The problems mentioned above are predominant at lower frequencies where the magnitudes of the Z-parameters are very small and highly sensitive to any issues in S. I don't think I've ever seen a case where renormalizing those ports to 50 Ohms was the best option, regardless of how high in frequency you are sweeping.