dielectric (slab waveguide) cst excitation

[mihailo93]

Hi, i hope that somebody can help me. I am new to CST and still having hart time figuring out how to excite my structures. My task is to simulate dielectric wave guide and plot evanescent fields in the air. I try using waveguide port but cant get the appropriate cutoff frequencies, even worse, fields in the air seem be occupying all the air.