I found another way of calculating the losses.
1.) Set up faces on those places in the model where the power should be calculated
2.) Set up a power monitor
3.) Solver run
4.) Calculate the integral of the power field calculated by the power monitor on the faces.
You can do this by "Template Based Post Processing" ->"2D and 3D field results" -> "Evaluate Field on Face" and chose the face and the power monitor as the field which should be evaluate. After that click on "evaluate" and you will get the integral value which corresponds to the total power. This works well for my model...
This method is described in a more detailed way in the following link:
https://www.cst.com/content/events/downloads/euc2012/talk_5-3-1_cst_euc_2012.pdf
If the mesh number is too high the simulation could take a lot of time since we use a power monitor for this method.
Maybe there's an easier way of calculating the power. I will look for another method. It would be nice if someone could describe his method if he knows of another way of calculating the power on different faces.
The problem concerning the F-Parameters:
I think I get the problem (higher losses than expected) since the reference signal is just a rectangular signal in the time domain whereas the output signal in the port is gaussian. Normally for the S-Parameters a gaussians function is taken as reference, but in case of a gaussian excitation a rectangular signal is taken as reference, which might lead to the high losses - I'm not sure.
My question is: What is the definition of the F-parameters. How can I find out the power/ losses with the help of F-Parameters while using a gaussian excitation as source?
Thanks in Advance