CST MWS problem： periodic boundary + waveguide port

Hi all,
I m trying to simulate a metallic periodic structure with the Transient solver, the structure composed periodic arrays in x-y plane and the wave incident from z-axis, I use periodic boundary conditions in both x and y direction, waveguide ports for top and bottom sides. When i run the model ,the following warning arises: Waveguide port 1 touches periodic boundary! ......
So, How can i set boundary conditions in x-y plane, need i use PEC + PMC instead? and, can i set waveguide ports inside the box?
Any suggestions are welcome!
Tks in advance.

Hai, in x axis u put magnetic and in y axis u put electric and in z axiz open
then one port in the top then u can measure the reflection .

Thanks u, James.
I wonder if you mean i should use PEC in x axis, PMC in y axis and set open and waveguide ports for up/bottom sides. I have tried the settings and it worked. But i don't know if it is right for unit cell without central symmetry? And how can i combine periodic boundary with waveguide ports?

I also had same problem. but i have set the all boundary as open add space. then i didn't get any such problem. but it will increase no of mesh cells.

dear kaandee,
Thanks very much
When do simulations with transient solver, We can't use periodic boundary directly. I have used PEC+PMC for x/y sides and open for z sides. Physically, PEC+PMC can serve as periodic boundary. You can use cell unit in frequency simulations, but frequency solver is slower than transient solver very much.
Zhang

PMC and PEC does not give the same result every time, I have the same problem because I want to use periodic boundaries in cst (in hfss it works very good but slower)

Does this simulate an array of periodic cells? What is the point of having the periodic boundary condition then if your suppost to use the magnetic in x and y electric?