HFSS15: Design Settings for HFSS-IE

The HFSS-IE>Design Settings command brings up a dialog with tabs for Material Thresholds, for Set Material Override and for Lossy Dielectrics.

The Set Material Override option allows some intersections to be resolved automatically in the mesh. If metal intersects dialectric, the metal overrides the dialectric in the overlap region. (That is, the metal object is subtracted from the dialectric.) If objects with the same material overlap, the small object overrides the larger. (That is, 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.

To use this feature, check Enable material override.

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. One 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.

You can use the Material Thresholds tab to set the thresholds for:

• Perfect Conductors in Siemens per meter.

Insulator Conductor in Siemens per meter

You can use the Lossy Dielectrics tab to automatically use casual materials. The options 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.

The Design Settings dialog also contains checkboxes on each tab to Save As Default.