How can I create a balun in CST?

Hi.
I′m simulating a antenna, but the feed point is not balanced..so a balun is necessary, unfortunately CST Help / examples, dont give me any help regarding this subject.
How can i create a balun in CST?
Thanks.

you should design a balun at first, then simulate it in CST and tune the parameter to meet your requirement.

but that′s my problem, i dont know what design i′ll do for the balun and how to feed it.
i′m simulating a loop, the balun should be in the center of the loop..so following the example of the yagi in CST, i feed the antenna with a discrete port with 197.5ohm expecting to have a result of 50ohm?
i was hopping to feed the antenna using a waveguide port..

please post the structure of your antenna and maybe someone can help you.

hi nadabro
I also need the details about balun coaxial feed in CST MWS. My model is two arm archimean spiral antenna . I want to use baluns coaxial feed. I don't know how to design in CST? Did you get any idea about it. Plz can you share with me.
thank you