Due to the different definitions of effective wavelength in different parts of your planar structure, you will see different mesh resolutions. For example, if you structure has several substrate layers with different permittivities, the mesh of metal traces on layers with a higher permittivity value will feature more cells than the mesh of metal traces on layers with a lower permittivity value even though the mesh density value is the same for the whole structure.
[[File:PMOM30.png|800px]]
Figure 1: Mesh of two rectangular patches at two different planes. The lower substrate layer has a higher permittivity.
=== Customizing A Planar Mesh ===