The integration between XFdtd and Optenni Lab enables matching network synthesis for antenna design. After an unmatched antenna is simulated in XF's full wave solver, S-parameters and efficiency data are passed to Optenni Lab where it synthesizes a matching network topology and component values.
Check XF Application Preferences
XF requires the location of Optenni Lab's executable in order to open Optenni Lab from the application's Results browser. XF can find and configure the executable automatically, or the location can be set manually in Edit ❯ Application Preferences ❯ External Tools if needed.
Run an FDTD Simulation
Optenni Lab uses S-parameter and efficiency results from an FDTD simulation to determine the desired matching network topology. In order to compute those results, all the standard steps in XF's workflow need to be completed—add geometry, define materials, specify the grid, etc. When creating a simulation, two of the window's tabs should be considered.
S-parameters need to be collected for each feed that will be matched in Optenni Lab. This is accomplished by checking the desired Active Feed(s) in the Setup S-parameters tab.
If the matching network will be synthesized in Optenni Lab based on efficiency data, then Frequencies need to be added in the Frequencies of Interest tab. Three to five frequencies per band are generally sufficient, but more may be needed for wide bands. Radiation and system efficiency will be available once steady-state data is collected.
Export to Optenni Lab
Users can launch Optenni Lab through the right-click menu of XF's Results browser when either S-parameters is selected, or both the S-parameters and Efficiency results are selected. The Ctrl key selects multiple results in the bottom portion of the Results browser.
For devices with a single active port, the two following results may be selected in the results browser before the Optenni Lab export option is enabled.
- S-parameters for the active feed, Sii
- System or radiation efficiency
Sii must always be selected, but efficiency is optional depending on the type of goals that will be set in Optenni Lab. It is not possible to export only efficiency.
These two results need to come from the same Simulation:Run. If a parameter sweep was performed, multiple Runs will exist in a single Simulation and care must be taken so results with different parametric values are not mixed.
For devices with multiple active ports, the following results may be selected in the results browser before the Optenni Lab export option is enabled.
- S-parameters for the active feeds
- A single system or radiation efficiency result
When selecting S-parameters, it is not necessary to select the full S-parameter matrix. It is sufficient for users to select one column of the S-parameter matrix (S11, S21, and S31 for a three port device). With this information, XF can determine the full set of results to send them to Optenni Lab. S-parameters for passive ports should not be selected. For example, S21 should not be selected if port 2 is passive and there is no corresponding S12 or S22.
Selecting efficiency is optional depending on the goals that will be specified in Optenni Lab. When needed, only one efficiency result needs to be selected in order to tell XF whether radiation or system efficiency is desired. XF then pulls the remaining data based on the S-parameter selection.
Parameter sweeps can be specified when creating an FDTD simulation, but caution is needed when calling Optenni Lab from the results browser because XF does not include error checking. The manual process therefore becomes error prone as the number of active feeds and parametric runs increases. For example, consider a simulation with an offset parameter. An allowable error would be to export S-parameters for offset = 2 mm with the system efficiency for offset = 2.5 mm.
Optenni Lab is automatically launched and populated with data when export to Optenni Lab is chosen in XF's results browser. The image shows Optenni Lab with XF's S-parameters and efficiency data in the project tree on the left of the user interface. Matching network synthesis is performed in Optenni Lab through Analyze ❯ Matching Circuit Generation.