Cell Size Calculator
Choosing a grid size to fit your geometry
One of the first issues that confronts the user of a shielded domain (FFT technique) Method of Moments electromagnetic analysis tool like Sonnet is the uniform background grid and the selection of an optimum grid. For circuits that are designed “on grid,” the selection of the simulation background grid is usually straightforward. However, in many cases we bring circuits to the EM simulator that have been designed without this assumption, and creative choices must be made in the grid selection to balance the simulation error requirements, sensitive dimension modeling error and the analysis resource requirements. The Sonnet Project Editor includes a Cell Size Calculator (Circuit->Box... menu). This calculator provides an aid to the selection of a grid size that meets your dimension modeling error requirements.
In the calculator, you list what you consider to be the critical dimensions for your circuits (gaps, line widths, spacings, etc.). A tolerance may be set for the error in the actual dimension and what the best grid snap will provide. The tolerance may be either global or specified for each individual dimension. As you change tolerances or add more dimensions, the calculator suggests optimum grid sizes. The cell size calculator takes the guesswork out of setting up your grid.
Sonnet cell size calculator provides a "best fit to tolerances" grid/cell size for EM analysis