7.9     Step by step simulation execution

In each FDTD simulation performed in QuickWave, we may distinct two main stages: pre-processing and the FDTD processing (actual FDTD simulation). In the pre-processing stage the software calculates template modes and generates the LC matrices. The FDTD processing stage is started automatically, immediately after pre-processing is finished. There are several situations in which we would like to execute the pre-processing stage in a user-controllable manner and then start manually the free run (with maximum speed, achievable for a considered project) of FDTD processing or proceed with FDTD processing iteration by iteration:

• Calculation of time integral of power dissipated, where it is required to start the calculation in Integral of Power Dissipated window from the first iteration,

• The FDTD simulation runs fast, hundreds/thousands of FDTD iterations per second, but the user would like to watch how the electromagnetic field propagates in the circuit with the consecutive iterations,

• etc.

QuickWave enables such possibility. The procedure of the simulation “step by step” execution is following:

1. Run QW-Simulator with Run command of QW-Editor.

2. In Run tab or Run main menu of QW-Simulator invoke Create command. Create command performs preparation for start of simulation but waits for further instructions at iteration number zero.

3. In the next step invoke Next Task command. Upon this command QW-Simulator completes the next task in the tasker (*.ta3) file, and then suspends operation. Typical tasker file contains the template generation commands and FDTD processing starting command. The goal is to reach simulation starting command thus the Next Task command should be invoked as many times as many template ports are included in the simulation project. Information concerning each of the performed tasks is reported in the Simulator Log window, as it has place in the automatic simulation running regime, and each Suspend command (invoked after completing each task) is also signalised.

4. After completing all tasks preluding the FDTD simulation starting command, information regarding e.g. activated post-processings, excitation, etc. are reported in the Simulator Log window.

5. The pre-processing stage has been completed. The next task will start the FDTD simulation. Depending on what was the purpose of executing the simulation step-by-step the user can run the FDTD simulation in two ways:

·       Open a required results window, e.g. Integral of Power Dissipated or 2D/3D Fields Distribution to enable the calculation of integral of power dissipated or observation of fields’ (or other variables) distribution from the first iteration and start the simulation free run using Next Task or Start command.

·       Open a required results dialogue, e.g. 1D Fields or 2D/3D Fields Distribution to enable observation of fields’ (or other variables) distribution. If it is required to observe how the distribution changes after consecutive FDTD iterations, the calculation of a single FDTD iteration should be invoked with Step command.

The use of this mechanism in practise is discussed in User Guide 3D: A basic time domain reflectometry (TDR) example.