What is the significance of this unit cell ?? What are you looking for.?
From CST help
The Unit Cell boundary condition virtually repeats the modeled structure periodically in two directions up to infinity. This dialog box allows you to define the periodicity of such an infinite array.
Note: Unit cell boundary conditions apply to the general purpose frequency domain solvers.
thanks for your reply. well i want to simulate EBG structure so i am not sure whether to use periodic boundary conditions or unit cell boundary conditions ?
because periodic boundary conditions also repeat the structure infinitely .
do you have any document related to unit cell or periodic boundary conditions applications