Simple 3D Plane Wave (RF module)

Dear Community,

As a first step to a more complex problem, I would like to model a simple 3D electromagnetic plane wave.

To do so I tried the following:
- draw a simple box, set material as air
- define 2 opposing faces as ports. The wave should be propagating normal to the port surface so I define Ex0=Ez0=0 and Ey0=1 for TE polarization and enter the propagation constant as being the wavevector corresponding to my desired frequency.

QUESTION 1: Is it sufficient to only enter the desired frequency implicitly here? Or will it be overwritten by some global default definition? I got the impression that upon changing the propagation constant the wavelength in the solution did not change at all.

- define periodic boundary conditions on the remaining 4 sides of the box

QUESTION 2: How should this be done? I tried Continuity and Floquet periodicity but neither of the two converged.

Thanks.