Faezeh Ladani
Ansys Employee

Hi Philipp,

It is expected to see different mesh when you replace the lumped ports by lumped elements. Now, by lumped elements, do you mean you have used circuit elements inside HFSS design? Or did you use Lumped RLC boundaries? 

If you use the latter, you should be able to import the mesh from Lumped port model since you can keep the geometry of both designs identical. This is the only criteria you need to import mesh. (By the way, if you have not used the feature before, read about it in the HFSS Help).

Also, if you are renormalizing lumped ports to some imaginary values, use Power definition for S parameters instead of Generalized which is the default. To set that, from menu go to HFSS> Design Settings...> S Parameters.