Modeling a Center-driven Dipole with HFSS (version 11.1.3)

Geometry and setup

Geometry: L= 1 m, a = 0.5 mm
Excitation: Lumped Port, 50 ohms
Mesh operation: Maximum length of elements=50 mm
Analysis Setup:
  • Solution Frequency: 300 MHz
  • Maximum Number of Passes: 50
  • Maximum ΔS: 0.01
  • Do Lambda Refinement: 0.5
  • Maximum Refinement Passes: 20%
  • Sweep type: Interpolate
  • Frequency: 50 MHz - 400 MHz, Step Size = 5 MHz

Download input geometry

Simulation result

Simulation Time: 3 mins 47 secs
Number of passes completed: 6
Number of tetrahedra: 14073

Decisions the user must make that affect the accuracy of the result

  • Location of absorbing boundary: λ/4 (at 300 MHz) away from the object
  • Source type: use lumped port
  • Maximum ΔS: default value = 0.02, this model=0.01
  • Do lambda refinement: default value=0.33, this model=0.5
  • Mesh operation: restrict the maximum length of elements
  • Dipole material: perfect conductor


  • What if we model the wire as a flat ribbon?

    We can substitute a 2-mm wide flat ribbon for the 0.5-mm round wire. The results are nearly the same.
    More information ...
  • Where was the absorbing boundary located?

    In HFSS, radiation boundaries are used to simulate open problems that allow waves to radiate to the far field. The accuracy of the radiation approximation depends on the distance between the boundary and the radiation source. The radiation surface must be located at least one-quarter wavelength from the radiating source. It should usually also be at a distance greater than the maximum dimension of the source.

    For this simulation, the solution frequency is 300 MHz (λ = 1 m). The radiation boundary is defined on a cylinder whose radius is 500 mm and height is 2000 mm.

Screen shots

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simulation model
Fig. 1. Simulation model
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simulation mesh
Fig. 2. Simulation meshes
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input impedance</>
Fig. 3. Input impedance
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input impedance at first resonant frequency
Fig. 4. Input impedance at the first resonant frequency