Finite ground CPW waveport

Hello ,

I want to simulate a W band 50 ohms finite ground conductor backed CPW line. I am using HFSS . I am not getting proper result. My problem is on changing the waveport size , the impedance of the CPW also changes for the fixed dimensions , so how can I exactly get the CPW dimensions for 50 ohms . My subs is er=3.38 and thickness=0.203mm.


PLz help me in solving it

I need it urgently.


Thanx in advance