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Hello [USER=134022]@D.A.(Tony)Stewart[/USER] ,

I am now trying simulating this portion of the cable :

[ATTACH=full]195035[/ATTACH]

I made some tests under Polar. Here are the data I used under polar (note the 100mm H1 substrate height to simulate no ground plane):

[ATTACH=full]195026[/ATTACH]

With these data, I got 115 ohm diff impedance :

[ATTACH=full]195027[/ATTACH]

Under HFSS, material are :

[ATTACH=full]195036[/ATTACH]

[ATTACH=full]195037[/ATTACH]

[ATTACH=full]195038[/ATTACH]

Under HFSS with terminal Wave port, I got about 70 ohm impedance :

[ATTACH=full]195029[/ATTACH]

[ATTACH=full]195028[/ATTACH]

And using lumped terminal port, I got about 130 ohm impedance :

[ATTACH=full]195032[/ATTACH]

[ATTACH=full]195031[/ATTACH]

I'm stuck on these problems I can't understand why I don't have consistent values with HFSS between modal & lumped ports and why I cannot get the right values polar give me ...

I tried to ask on ansys forum but get no answer.

I am trying to get an acces to ansys learning hub to ask for help but it's difficul to get a free acces...

[automerge]1730465521[/automerge]

I also tried this lumped port configuration:

[ATTACH=full]195040[/ATTACH]

And still get about 130 ohm:

[ATTACH=full]195041[/ATTACH]

[automerge]1730468272[/automerge]

Using polar, I get these different values for the impedance :

[ATTACH=full]195027[/ATTACH]

It seems that:

 - Lumped port configuration give me the Even Mode impedance

 - Wave port configuration give me the Common mode impedance

Do you think it is chance ??

My HFSS project is here : https://drive.google.com/file/d/1jEWDVxm6hTSQ0ILNnNiVQMt1N1CC-aNG/view?usp=sharing