Frequency Sweeps in Q3D Extractor

To generate a solution across a range of frequencies, add a frequency sweep to the solution setup. Q3D Extractor performs the sweep after the adaptive solution, if one is defined. If an adaptive solution is not requested, the sweep is the only solution generated. You can also disable a sweep and run only the adaptive solution (or a ports-only solution) without the sweep, then later reactivate the sweep.

Adding a Frequency Sweep

To add a frequency sweep:

1. Open the Edit Frequency Sweep window one of two ways:
   • Select Q3D Extractor > Analysis Setup > Add Frequency Sweep and select the solution setup to which the sweep applies.
   • In the Project Tree, right-click the setup to which the sweep applies and select Add Frequency Sweep.

   The Edit Frequency Sweep window appears.

   

   Note:

   The available tabs and options change with the selected sweep type.

2. Specify the sweep parameters:
   • Sweep Name – enter a name for the sweep.
   • Sweep Type – select discrete or interpolating:
     • Discrete Sweep – Generates field solutions at specific frequency points in a frequency range. Best when only a few frequency points are necessary to accurately represent the results in a frequency range.
     • Interpolating Sweep – Estimates a solution for an entire frequency range. Best when the frequency range is wide and the frequency response is smooth. When you select Interpolating sweep, the Interpolation tab appears, where you can specify the maximum number of solutions, minimum number of solutions, and error tolerance. See Step 4 below.
       Note:

       The information specified for an Interpolating sweep dictates the amount of information that can be viewed on a post-processing plot.

   • Enabled – select to enable the sweep or clear the check box to disable it.
   • Frequency Sweeps – use the Add Above/Add Below and Delete Selection buttons to add or remove sweeps.

     Each row represents a separate sweep. Selecting a sweep's Distribution activates a drop-down menu allowing you to select the type of sweep:

     • Linear Step – A linear range of frequency points for which you specify a constant step size. Q3D Extractor will solve the frequency point at each step in the specified frequency range, including the start and stop frequencies. For example, specifying 10 for the start frequency, 20 for the stop frequency, and 2.5 for the step size instructs Q3D Extractor to compute a solution for frequencies of 10, 12.5, 15, 17.5, and 20.
     • Linear Count – A linear range of frequency points for which you specify the number (count) of points within the frequency range. Q3D Extractor will divide the frequency range into the count you specify and solve each frequency point in the count.
     • Log Scale – A range of points for which you specify the start, end, and number of samples. Q3D Extractor assigns the sampled points using intervals based on a logarithmic scale.
     • Single Point – Individual frequency points. You can insert specific frequency points that you want to solve in the frequency range after you have added uniform frequency points to solve.For Discrete sweeps only.

     You can add multiple sweep types to the same setup.

     Specify the Start and End frequency for each sweep, as well as any additional options for that sweep type.

   • 3D Fields Save Options – for discrete sweeps only, you can select Save Fields (all frequencies) to save the calculated 3D field solutions associated with the chosen frequencies.

3. Click Preview to view a preview of the sweep, as currently defined:

   

4. If you are running an Interpolating sweep, select the Interpolation tab to specify additional settings:
   • Max Solutions – the maximum number of solutions that will be solved for the frequency range. The default is 50.
   • Error Tolerance – the maximum relative difference allowed between two successive interpolation solutions. The default is 0.01 percent, which is usually satisfactory.
   • Minimum Solutions – the minimum number of converged solutions that will be solved for the frequency range. For example, if this value is three, then once the sweep reaches convergence it simulates at two extra frequencies. This resembles the minimum number of converged adaptive passes in a regular simulation. Setting a minimum number of solutions can eliminate non-physical S-parameter spikes. The default value is 0.
   • Minimum Number of Sub Ranges – the sub range number acts as an initial condition on the sweep to force initial even breakup of the null range into subranges. The end points and middle of each subrange will be solved. This controls the points at which the interpolating sweep is broken up and prevents redundant effort caused by neighboring interpolating sweeps solving the same point. For example, the 1GHz to 4GHz and the 4GHz to 9 GHz sweeps do not both solve the 4 GHz datapoint. The default value is 1.

5. If desired, select the Defaults tab to save your settings as the default or change your settings to the current default settings.
6. Click OK to add the sweep.

   The sweep appears in the Project Tree:

   

Enabling and Disabling a Frequency Sweep

To disable a Frequency Sweep without deleting it, right-click the sweep in the Project Tree and select Disable Sweep.

Disabled sweeps appear grayed out in the Project Tree (see Sweep2 in this example):

To enable a disabled Frequency Sweep, right-click the sweep and select Enable Sweep.

Deleting a Frequency Sweep

To delete a sweep, right-click it in the Project Tree and select Delete.

Duplicating a Frequency Sweep

You can duplicate an existing frequency sweep by right-clicking it and selecting Copy (or by using Edit > Copy), then selecting the solution setup and pasting the sweep. By default, the copy is named Sweepn, where n increments with each new sweep. You can then edit each copy to make desired changes.