XF's post-processing option allows users to make use of the electromagnetic principle of superposition in order to combine steady-state results from a single FDTD simulation that computed S-parameters for multiple ports. The superposition capability requires users to provide the set of port magnitude and phase values used to combine the results. See the antenna array use cases knowledge article for prerequisites and use cases.
Users can create a superposition simulation through the Simulations window by choosing Post Processing ❯ Superposition Simulation as the Create Simulation option in the upper-left corner, or through the Results browser by right-clicking on an existing superposition result and selecting Create New Superposition.
In the Create Superposition Simulation window that opens, the Name field at the top of the window provides space for a user-defined simulation identifier. This name appears in the Simulations window once the simulation is created, and is editable from that window through the right-click menu.
The Superpositions tab allows users to choose the source of steady-state results for post-processing and specify the magnitude and phase for each port.
The Input Project drop-down menu lists projects that are loaded in the current project's Results browser. This selection determines which input simulations are available.
The Input Simulation drop-down menu lists simulations that belong to the selected input project. This selection determines the steady-state results available for superpositioning.
The Superpositions table allows users to specify which of the selected simulation's ports are active when the steady-state results are combined. The Name column provides an identifier for each set of ports and the Active Ports column lists the ports included in the associated superposition.
Two buttons above the Superpositions table control its contents:
- The button adds a superposition to the simulation.
- The button removes the selected superposition from the simulation.
Add a Superposition
Clicking the button opens the Edit Superposition window that allows users to create a superposition and choose which excitations it combines.
Two buttons provide options for choosing components:
- Select All: includes all available components in the superposition.
- Deselect All: excludes all available components from the superposition.
Users can also include or exclude an individual component by selecting or deselecting its associated checkbox, respectively.
The Name field at the top of the window provides space for a user-defined superposition identifier. This name appears in the listed Superpositions once it is added to the simulation by clicking the OK button. Clicking the Cancel button closes the Edit Superposition window without applying the most recent changes.
Users can adjust the magnitude and phase applied to each port before adding it to the simulation by clicking the Edit Superposition Definition button.
Edit Superposition Settings
Clicking the Edit Superposition Definition button opens the Superposition Definition Editor window that allows users to define the magnitude and phase for each port, steady-state frequency, and parameter value. Users can access these settings for an existing superposition by double-clicking on the desired superposition listed in the Create Superposition Simulation window.
The Superposition Run setting differs from the simulation run referred to when creating an FDTD simulation. The Superposition Run drop-down menu lists each parameter value in a parameter sweep, not the total number of runs in the input simulation. The drop-down menu typically consists of one run because most FDTD simulations do not include a parameter sweep. For example, an FDTD simulation containing 11 feeds and no parameter sweep has 11 runs, but superpositioning condenses those FDTD runs into one available run.
The Frequency drop-down menu lists each of the steady-state frequencies specified in the input simulation. Users can define the available power and phase for the selected frequency.
The Port column displays each active port selected in the Edit Superposition window.
Each Available Power field determines the deliverable power of its corresponding component at the selected frequency. This value defines the component power used when computing superposition results. Users can enter a different value for each separate frequency.
Each Phase field determines the phase offset applied to its corresponding component at the selected frequency. This value defines the phase offset used when computing superposition results. Users can enter a different value for each separate frequency.
Users can also access this editor for an existing superposition result by right-clicking on the desired superposition result in the Results browser and selecting View Superposition Definition.
The Notes tab provides space for users to attach memos to the simulation, such as a brief description of its specifications for later reference. When a note was attached to a previous project, the Use Last button is enabled and allows users to apply that same note to the current simulation setup. Once the simulation is created, these optional notes appear in the notes tab of the simulations window, and are editable in that window by right-clicking on the desired simulation and selecting from the menu.
Unlike the other simulation types—FDTD, response matrix, array optimization—a superposition simulation does not kick off a separate executable. Instead, the superposition principle is used to combine steady-state results in realtime when results are accessed.
Three buttons provide options for completing the simulation setup:
- Create Simulation: closes the Create Superposition Simulation window and adds the simulation to the Simulations window. Results for the superposition are available once the input FDTD simulation is complete and the Results browser is refreshed.
- Done: closes the Create Superposition Simulation window but saves the entered specifications, which are visible when the window is re-opened.
- Cancel: closes the Create Superposition Simulation window and does not save the entered specifications.