5.5    Template mode generation procedure

In general, if the simulation project contains transmission line ports, the simulation starts from generating template of the transmission line mode to be considered at each port. The template mode is simply the spatial field distribution in the transmission line port plane. The template mode generation process is a part of the so-called pre-processing stage of FDTD simulation. The information about the processes performed in this stage, including template mode generation, are listed in the QW‑Simulator in the Simulator Log window.

In QW-3D there are two kinds of templates resulting from the procedure of template mode generation: dynamic and quasi-static.

In QW-3D there are three available regimes of calculating thetemplate mode: automatic, analytical, and manual. The user can take advantage of all three in case of dynamic templates but the quasi-static (TEM) templates are always calculated automatically.

Let us point out that in the case of QW-V2D software template generation proceeds in a similar way. The most important difference is that while in QW-3D software a 2-D template is generated (since we have a two-dimensional cross-section of the port) in QW-V2D software we need to generate 1-D template on a single column of FDTD cells across the port line. However in QW-V2D environment there is much smaller variety of possible modes and the default choices are sufficient in almost all practical cases. Also, the analytical template mode generation procedure is not enabled, since it was introduced to eliminate the long template generation times appearing for very large number of FDTD cells in the template port plane. This may appear in 3D simulation scenarios but, due to its nature, is not crucial in QW-V2D. The need for more detailed study of the template generation in case of QW-V2D may practically occur only when we need to use a circular waveguide port with inhomogeneous dielectric filling. In such case the QW-V2D user is encouraged to read subsection about manual generation of dynamic template and User Guide 3D: First insight template generation - low-order waveguide modes to understand the idea of manual template generation and in case of further questions seek answers at QWED support.