Perfect Boundary Approximation
The Perfect Boundary Approximation (PBA) is used for the spatial discretization of the structure. The simulated structure and the electromagnetic fields are mapped to a hexagonal mesh. PBA allows a very good approximation of even curved surfaces within the cubic mesh cells.
PBA and mesh cell size
This works very well as long as the approximated structure is greater than the cell size of the mesh. Because, as in every discrete systems, the resolution of the method is limited by the sampling width. This means, that small details of the structure will be modeled accurately only if the mesh cell sizes are smaller than these details.
See also
Mesh View (Hexahedral), Special mesh properties, Hexahedral Mesh