CST MICROWAVE - Discrete or wave guide port is suitable?

[hudaaqeel]

I have design a microstrip patch antenna in CST to calculate s- parameter at 28 GHz, which port is suitable (discrete or wave guide) ?
When I change the port I have different results , even an impedance mismatch has occurred.

 

[Geralt_of_Rivia]

The best way to do this is by using "Calculate port extension coefficient" macro (Macros->Solver->Ports) in CST