Assigning waveguide port in CST

Hi everyone,
I'm designing a microstripline in CST for which I need to assign a port in order to simulate the design at different frequencies. Now in order to set a similar condition as in real life, I need to use a port at 50ohm characterestic impedance. I'm going to use an sma port during fabrication. Hence how can I account for a 50ohm waveguide or discrete port in CST? I'm also unsure whether a waveguide port or a discrete port is more suitable in this case.
Many Thanks in advance!

You can set the impedance using a discrete port (take S-parameter port, you can then set the impedance directly). But it will become inaccurate if the guide is a few wavelengths or larger.
With the waveguide port you'll get the impedance defined by the geometry of the guide and the mode you inject. You can optimize it to the value you want by changing the geometry (e.g. use the optimizer or a parameter sweep and record the line impedance).