CST2013: Special Solver Parameters - General

Simulation: SolverStart SimulationSpecialsGeneral

General settings frame

Stability factor for timestep: Enter here a stability factor that will be multiplied to the current valid stability limit for the numerical timestep. In case that a time domain calculation shows some slight effects of instability, a small reduction of the stability factor might recover a stable state. Note: Choosing a factor greater than one is not advisable and will likely produce instability.

Restart solver after instability abort: If this check button is activated, the solver is automatically restarted twice with a reduced timestep after an instability abort. In case that the occurred instability is due to the time discretization, this process helps to provide a stable simulation during the restarted run.

Consider two-port reciprocity with energy balance limit of ... : This check button enables the possibility that the S-Parameters for two-port structures meeting the condition of reciprocity (loss-free two-port system) will be mirrored by the solver, so that only one simulation run is performed. This reciprocity condition is determined by checking the energy balance: For reciprocal and loss free structures the energy balance should be one. If the difference of the simulated balance to one is less than the given limit value over the whole frequency range the structure is assumed to be loss-free.

Please note that no fields are calculated for the mirrored port. If this option is not set, the transient solver performs all calculation runs even for symmetric ports. Also in case of distributed ports the setting of the reciprocity check box is ignored and all calculation runs are performed remotely.

Automatic time signal sampling: If this check button is enabled, the transient solver automatically samples all time signals that are written to disk in order to reduce the data amount while still fulfilling the sampling theorem. By deactivating this automatic functionality the signals are written with highest possible sampling rate, i.e. every timestep.

TDR analysis: If this check button is enabled, the transient solver performs an online TDR analysis for step or Gaussian excitation signals and adds the corresponding signal curve into the result tree. The TDR calculation is applied for single port excitations of discrete ports or waveguide ports with (Q)TEM modes.
Please find more detailed information about TDR analysis on the general help page for Signals in Transient Simulations.

Use broadband phase shift with lower bound factor of ... : If this check button is enabled, the phase shift defined either in the simultaneous excitation dialog or in the plane wave setup dialog will be considered as a broadband behavior and thus ignoring the corresponding reference frequency setting, respectively. The broadband phase shift filter is computed by means of a Hilbert filter which guarantees accurate results in the frequency range [ lower bound factor * fMax, fMax ] where fMax is the upper simulation frequency range.

Ensure shielding for all ports: If this check button is enabled, a shielding frame of PEC or PMC type surrounding each waveguide port region will be added. This option causes higher reflections at ports. Therefore, it should only be used if a calculation has become unstable. Note that this setting will be ignored for already electrically shielded waveguides (e.g. coaxial waveguides). Leave this button unchecked to apply the default treatment for waveguide port boundaries.

Frequency settings frame

Fmin / Fmax: These text fields are for information purposes only. They display the minimal and maximal chosen frequencies. To change these values, you may go into the Frequency Range Setting dialog box in the Main menu under Solve Frequency....

Samples: Here, you may specify the number of samples that will represent the S-Parameters. Please note that the simulation has to be repeated, if you change this number. Please note that this number has nearly no effect on the total simulation time!

OK

Accepts the input and closes the dialog.

Cancel

Closes this dialog box without performing any further action.

Help

Shows this help text.

See also

Solver, Signals in Time Domain Simulations Overview,

Special Solver Parameters: Waveguide, Steady State, AR-Filter, Material, Solver