simulate coaxial cable impedance in CST

I've design inner, outer and dielectric to get desired impedance. I try to simulate in CST but:
I try to use port ( can define impedance) but can't simulate due to the port must not in PEC.
I try wave port but I can not define system impedance .
Pls give suggestion.

Hi, u could try to design the waveguide port around the dielectric. I have attached an image below. Pick face the dielectric and increase the width to around 0.1 You should get the impedance. I did it for 50 OHm.