Ansoft Hfss

Importing Drawing:

  • Using GDS2 allows layer definition via *.tech file. the tech file defines the layer thickness and the layer distance. The unit given in the files is "nm" (nanometer).
  • File Import via GDS2 and tech-files is very easy and reduces drawing in the HFSS window.
  • An example file:
//--------------------------------------------------------
// L#    Label       Color        Elevation(nm)    Thickness(nm)
//-------------------------------------------------------- 
1    M1       red         1448000        40000
2    M2       green       1338000        40000
3    M3       blue        1081000        17000
4    M4       pink        864000        17000
5    M5       gray        607000        17000

Model considerations:

  • Objects should not overlap. Objects should "touch" or be complete solids —> Either subtract or unite objects
  • Dielectric Box should surround conductive objects —> Conductors must be subtracted from dielectric box (boolean subtract with clone object)
  • In menue under "HFSS —> Set Material override" it can be selected, that metal overrides dielectric material (subtract not necessary in this case)
  • If using Lumped Ports a big vacuum box containing the simulation structures is required

Ports and Excitation:

  • Wave Ports are excited from external faces (select HFSS —> Solution Type —> Driven Modal)
  • Lumped Ports are excited from inside the boundary area (select HFSS —> Solution Type —> Driven Modal)

Using Lumped Ports, a 2D-sheet should connect to the two conductors required for excitation. It can be selected which of the two conductor faces is the reference port.

Driven Modal:

  • Expressed in terms of the incident and reflected powers of the waveguide modes

– Definition not desirable for problems having several propagating quasi-TEM modes.

  • Coupled/Multi-Coupled Transmission Lines
  • Always used by the solver
  • Calibration: Integration Line

– Phase between Ports
– Modal voltage integration path: Zpi, Zpv, Zvi.

Driven Terminal

  • Linear combination of nodal voltages and currents for the Wave Port.

– Equivalent transformation performed from Modal Solution

  • Calibration: Terminal Assignments

– Polarity
– Nodal current integration path

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