[CST Studio][Periodic Graphene， plane wave excitation][help]

hi,
i am using CST studio to simulate periodic graphene on substrate.
I got the graphene surface impedance from the kubo formula calculated in matlab and set the graphene as a sheet material.
from the reference paper, it says: "The plane wave is normally incident on the 2D periodic structure with Ex-polarized. The reflectance of the fundamental space harmonic, (0, 0)th order, are calculated.
there is a ground plane beneath the substrate, and then the graphene on top.
i am not sure about the boundary conditions and the waveguide ports.
i have set zmin = conducting wall, zmax = open add space
x- electric = 0 y - magnetic = 0
one waveguide port at zmax, setting the excitation at port one, and running the frequency solver.
is this the correct way? i cant get the results in the paper

can you please tell me the reference paper you mentioned?