=== Planar Mesh Density ===
EM.Cube's [[Planar Module]], by default, generates a hybrid mesh of your planar structure with a mesh density of 20 cells per effective wavelength. It is important to understand the concept of mesh density (either hybrid or triangular) as used by [[Planar Module]]. It gives a measure of the number of cells per effective wavelength that are placed in various regions of your planar structure. The higher the mesh density, the more cells are created on the geometrical objects. Keep in mind that only the finite-sized objects of your structure are discretized. No mesh is generated for the substrate layers of your background structure. The free-space wavelength is defined as ?<submath>0\lambda_0 = \tfrac{2\pi f}{c}</submath> = 2pf/c, where f is the center frequency of your project and c is the speed of light in the free space. The effective wavelength is defined as ?<submath>\lambda_{eff</sub> } = ?<sub>0</sub>/ve<sub>\tfrac{\lambda_0}{\sqrt{\varepsilon_{eff}}}</submath>, where e<sub>eff</sub> is the effective permittivity.
The effective permittivity is defined differently for different types of traces and embedded object sets. For metal and conductive sheet traces, the effective permittivity is defined as the larger of the permittivity of the two substrate layers just above and below the metallic trace. For slot traces, the effective permittivity is defined as the mean (average) of the permittivity of the two substrate layers just above and below the metallic trace. These definitions of effective permittivity are consistent with the effective propagation constant of transmission lines realized on such trace types. For embedded object sets, the effective permittivity is defined as the largest of the permittivities of all the substrate layers and embedded dielectric sets. In all cases, for the purpose of calculating the effective wavelength, only the real part of the permittivities are considered. The reason for using an effective wavelength so defined for determination of mesh resolution is to make sure that enough cells are placed in areas that might feature higher field concentration.