# Auto Determine the Mesh Sizes

A mesh can be created quickly without you having any knowledge of what the ideal mesh size should be for the model. Use the coarse, standard or fine mesh size to determine the correct mesh size for the model that takes into account the frequency, solution method, media properties and curvature of the model.

When the mesh size is determined automatically, the mesh is discretised relative to the wavelength of an electromagnetic wave in the medium of propagation. Each solution method has different requirements that influence the mesh size. In most cases, the automatic mesh size using the coarse, standard or fine option will give a reasonable result, but local mesh refinement may still be necessary.

The following model properties are considered when creating an automatic mesh size using the coarse, standard or fine option1:
Frequency
The simulation frequency of the model impacts the automatic mesh generated. The shortest wavelength corresponds to the highest simulation frequency.
Solver method
The solver method being used to solve the problem impacts the mesh requirements. For example, a finite element method (FEM) model requires settings for tetrahedra, a method of moments (MoM) solution requires settings for triangles and wires, while a hybrid solution needs to take into account the mesh requirements for multiple solution methods.
Dielectric properties
The dielectric properties of the media in the model affects the wavelength. Dielectric media are taken into account in all cases (except in the case where infinite layers are used). In the case where infinite layers are used, a local mesh refinement must be applied.
Geometry curvature
In cases where a finer mesh is not paramount for accurate solution results, it may still be required to accurately model aspects of the geometry. An automatic mesh size will attempt to reasonably conform to the original geometry.
Tip: Modify the mesh settings on the Create mesh dialog, on the Advanced tab and note the effect the settings have on the resulting mesh.

Automatic mesh settings are only applied to regions, faces, edges and wires that do not have a mesh size set (locally or globally). When a local mesh refinement is applied to an individual component in the model, the local mesh refinement receives higher priority and will never be overwritten by the automatic meshing sizes.

1 The coarse, standard or fine mesh option is available on the Modify Mesh dialog.