CST2013: Time Domain Solver Problem Handling

This page contains a list of the most important warning and error messages  in the context of the transient solver together with a detailed explanation of the meaning and proposal for handling and resolution.

Maximum number of pulse widths simulated, solver stopped. / Maximum simulation time reached, solver stopped. Please note that the steady state energy criterion has not been satisfied.

The transient solver operates with a time pulse as excitation, and the simulation stops when one of the following conditions are met:

• Either the remaining energy in the calculation domain as well as the port signals have decreased to the steady state value specified on the time domain solver parameter page in the Accuracy field.

• The simulation time reaches the maximum solver duration, either defined as Time, Number of pulses or Propagation distance on the Steady state tab on the Special Time Domain Solver Parameter page.

The warning appears when the latter condition was satisfied first before the accuracy level has been reached. This means the energy level remaining in the structure is still bigger than the specified steady state value. Usually this is the case for resonating (energy stays inside the structure for a long time) or large structures (it takes a long time for a pulse to penetrate through the structure). The extra energy would appear as a truncation error, which causes some ripples in the S-parameter curves.

Recommended solutions are the following:

• For non-resonating structures, the maximum solver duration setting can be adjusted, with the appropriate choice of defining number of pulses or a time or propagation distance setting.

• For resonating structures a much better approach would be to activate the Autoregressive Filter (see advanced Topics manual) on the AR Filter tab on the Special Time Domain Solver Parameter page, which allows to shorten the simulation time and in addition to avoid the truncation error.

Farfield probe "xxx" is not considered in time domain calculation because it is positioned below a closed boundary referring to the origin setting.

In general a point or probe location on a farfield sphere is determined by a direction and a radius, i.e. a three dimensional vector r(farfield). In Cartesian coordinates this is given by the definition of two spatial points, the probe position r(probe) and the origin r(origin). The vector for the farfield calculation is then given as r(farfield) = r(origin) - r(probe). The above warning is shown when this vector points below a certain closed boundary.