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Stripline in EMpower

Question asked by mburfo on Feb 21, 2007
Dear all,
I am having difficulty creating a stripline geometry in EMpower.

I have done the following:
Used 1x1mil grid size.
Stackup is:
Top cover
Air (4000mil)
Top shield (rogers 0.71)
dielectric (rogers 4350 8mil)
diff_pair (w=8, s=6, rogers 0.71)
dielectric (rogers 4350 8mil)
Bottom cover (rogers 0.71

I have tried using stitching vias to connect the top shield to the botom cover.
I am also using the modal simulation.
The ports are on the same layer as the diff_pair and are 'normal and default' in every manner.

The top shield goes to the edge of the simulation box.

My problem is that using TLine and also other 2D field sovlers they come up with Zoo as 43.7 and Zoe as 54.6 ohms

Can anyone suggest how I can achieve a true stripline geometry that presents the correct impedances for odd and even modes?

I do not want to use the top cover as the top shield.

Thanks so much for any assistance given

EMpower does not give near these values