7       FDTD Mesh

Mesh refers to the set of FDTD cells. These cells of cubicoidal (or cubicoidal cut by a plane) shape have the basic size defined through the Mesh Parameters dialogue. However, the actual cell size may be modified downwards by the software to fill the area between mesh snapping planes with an integer number of cells. Mesh snapping planes are either introduced explicitly by the user (via Special Planes and Boundaries or Snapping Plane dialogues) or forced automatically by the QW-Editor (for example, at horizontal boundaries of metal elements).

The user is recommended to verify the actual settings of the mesh and special planes (in the Mesh Info dialogue or in the Amigo dialogue) before running the simulation. If two Snapping Planes are accidentally introduced too close to each other, they force a small FDTD cell, which leads to a small time step, and hence prolongs the simulation time. To warn the user about the existence of such closely situated special planes, they will be marked in 2D Windows by red points at the external contour of the grid.