Adding Length-Based Mesh Seeding to an HFSS 3D Layout Design

Length based mesh refinement controls the length of the tetrahedral elements and the growth of the whole mesh. Set a ceiling on the mesh growth with the option Restrict the Number of Elements to ensure a mesh of reasonable size after the length refinement.

When a mesh operation is defined and a maximum length is set, on a selection of nets and layers (i.e., more than one), the operation occurs on the whole mesh. If only one layer or net is selected, when its boundaries are refined, elements are added both inside and outside of that object.

When there are no more elements to refine or when no more elements can be added, the refinement process stops because it has either met the growth limit or the element length target. However, there are more quality improvement swaps, smoothing, and matching boundary issues, performed at the finishing stage that might slightly alter the mesh size.

1. From the Layout Editor, pick any selectable(s) on the net-layer pair(s) for assignment. This is optional. The selection are used to initialize the assignment window.
2. From the Project Manager window, right-click project' s HFSS Setup analysis.
3. Choose Assign Mesh Operations > On/Inside Selection > Length Based to open the Select Geometry window.

   

4. Select the selected net-layer pairs, including the airbox, and assign the seeding attributes. If necessary, display and filter for nets.
5. For On Selection:
   1. To restrict the length of tetrahedra edges touching the faces:
      1. Select Restrict Length of Elements.
      2. Type the maximum length of the tetrahedral edges touching the faces in the Maximum Length of Elements field. HFSS refines the element edges touching the selected faces until their lengths are equal to or less than this value.
   2. To restrict the number of elements added during refinement of faces:
      1. Select Restrict the Number of Elements.
      2. Enter the Maximum Number of Elements to add. When the mesh is generated, the refinement criteria specified is used. If the maximum number of elements is reached, some elements may exceed the requested maximum element length.
6. For Inside Selection:
   1. To restrict the length of the tetrahedral element edges inside the object:
      1. Select Restrict Length of Elements.
      2. Type the maximum length of the edges inside the selection in Maximum Length of Elements field.
   2. To restrict the number of elements added during the refinement inside the object:
      1. Select Restrict the Number of Elements.
      2. Enter the Maximum Number of Elements to add.
7. If seeding the mesh by region, use the Region Selection area to select one region.
8. Click OK.