What causes critical cells to be expanded to the full size? CST

[xxgcatz]

I want to know if the waring " 46 critial cells have been expanded to the full size " affect the result ! And what reason cause that ? Who can tell me ! thanks !

 

[yuyu]

critical cells have been expanded to full size

Hi xxgcatz,

until v.3 of CST Microwave Studio when you have three materials in one cell, where the middle layer is metal, you have a critical cell.
In fact, to avoid e.m. coupling through the thin metal (in practise, the thin metal is not considered or not seen, by the simulator) such a cell is completely filled with metal. Otherwise both dielectrics would be connected!
With v.4 it was introduced the TST (Thin Sheet Technology) that enables to have two non PEC region within a single cell.
Anyway, if there are more than two PEC areas in one cell or one single PEC area, which is completely inside the cell, this whole critical cell has to be filled with PEC material and, again, you have critical cells.
In this case you have two possible solutions;
it is possible to make thicker one or more PEC areas (if the change is not meaning) or refinement the mesh.

Of course, if the cells filled with PEC (critical cells) don't change the e.m. problem it is possible to leave the same mesh.

You can also see this paper about CST Microwave Studio meshing(Microwave Journal aug 2002).

Regards.