Mixed mode S parameter to 200Ohm system

[yzriver]

Hi all,
Could anyone know the conversion of 4-port s-parameter to mixed mode parameter?

the case is that I have a differential in (2 ports) and differential out (2 ports) unit. I measured the 4 port s parameter into a S4p file. This s4p is measured on a 50Ohm system. I need to convert it to the mixed mode s-parameter on 200 ohm, what can i do?
I find the equation for 50ohm to 50 ohm conversion, but can't find the equation for the conversion between different impedance.

thank you for you reading.

 

[RF-OM]

Search Agilent web site. They have Application Note(s) for this issue. It can be done with transform S-matrix to T-matrix and then back to S-matrix if I remember it right. I used this techniques a couple of times, but do not remember all the details. Once we developed this technology and created Matlab file, we use it since that. It is based on Agilent papers I mentioned earlier. But because equations are hidden in the program I cannot see them and recall everything.