Design Settings for Q3D Extractor

To set the design settings for Q3D Extractor:

1. Click Q3D Extractor > Design Settings.

   The Q3D Design Settings dialog box appears, on the Set Material Override tab.

   Enable material override allows some intersections to be resolved automatically in the mesh. If metal intersects dielectric, the metal overrides the dielectric in the overlap region, and the metal object is subtracted from the dielectric. If objects with the same material overlap, the small object overrides the larger - the small object is subtracted from the larger. All other intersections are treated as errors. Normally, the modeler considers any intersection between 3D objects to be an error. In the meshing process, the dielectrics are locally overwritten by the metals in the intersecting region. That is, the part of the dielectric that is inside the metal is removed, and if the dielectric is completely inside, the whole object disappears. The purpose of this feature is to allow you to avoid doing explicit subtraction in the modeler. An example application is a via that passes through many dielectric layers - with the option turned on, the via does not have to be subtracted from the layers.

2. In the Design Settings window, click through the tabs to set various options.
   • The Background tab shows the background material assignment.

     Clicking the button opens the Materials window.

   • The Lossy Dielectrics tab contains options for causal materials.

     Automatically use causal materials causes objects with constant material permittivity greater than one and dielectric loss tangent greater than zero to be treated as frequency dependent. Their actual permittivity and conductivity will be determined by the Djordjevic-Sarkar algorithm, and the loss tangent will be zero.

     Important:

     Automatic casual material calculations are not performed under the following circumstances:

     • If the material permittivity or loss tangent is anisotropic.
     • If the material permittivity or loss tangent is frequency dependent.
     • If the material itself is not a lossy dielectric.
   • The S Parameters tab allows you to choose a calculation method.

     You can select either the Equivalent transmission line model or the Lumped RLGC model.

   • The Validations tab controls the extent of validations performed and, therefore, the time involved.
     • Select model validation choices: either Ignore unclassified objects or Skip intersection checks.
     • Control the Entity Check Level as Strict, Basic, Warning Only, or None.
     • Choose Perform full validations to do all design validations, or Perform minimal validations to run all design validation except boundary overlap checks and net validations.

3. If desired, select Save As Default on any tab. You must be careful since these settings change the modeler's "ground rules" and may produce unexpected results.

4. Click OK to accept your selections and close the dialog box.

You can also view and set Design Settings by selecting the current project and then the Q3D tab in the Properties window.