Why Sonnet port impedance different from Normalizing impedance

Hi,

I am doing a simple Sonnet microstrip transmission line simulation. In the Editor, I set port impedance to 100 Ohm, say, just for fun.

Then, after a simulation, the Response viewer reported me a set of S11 value. I recorded it. On the Response viewer screen, it showed Z0 = 50 Ohm.

Now go back to the Editor, I changed the port impedance to 1 Ohm, again, just for fun.

After another simulation, the Response viewer reported me the same set of S11 ! How come ? On the Response viewer screen, it showed again Z0 = 50 Ohm.


I assumed that, even I changed the port impedance in the Editor, the S11 results were still based on Z0=50 Ohm normalizing impedance as shown on the Response viewer screen. Is this so confusing to you all Sonnet user ?

For me, I would expect that S11 shown in the Response viewer will follow the port impedance I already set in the model Editor.

Did I misunderstand something ?

Thanks a lot,

DYL

Still don't know exactly where this issue comes from. But I figured out that I needed to delete old ports, placed them again, delete Sonnet data folder and re-simulate. After that everything is fine - normalizing impedance in Response viewer follows Port impedances set in Editor.

DYL

Sonnet USA support has identified the problem, which is related to saved states in the Sonnet 13 results viewer. These saved states are not updated with the new reference impedance.

"The best approach for you is to use the following steps:

1) Disable the “Save State” feature in the Response Viewer – Use the command File => Preferences. Under the "General" tab, check the box labeled "Ignore automatically saved graphs and use defaults".

2) Use the Circuit => Ports method to change the Port Termination values.

3) Re-simulate the model after changing the Port Termination. This should just be a renormalization.

4) Open the data in the Response Viewer and you should see the desired data and behavior now. "