The Params page

The upper half of this page provides entry areas for parameters used by the interface related to the substrate, plus a menu for choosing the units to use in the list file.

SubstrateThickness
This sets the assumed substrate thickness in microns. When the thickness is nonzero, the substrate bottom and sides are assumed to abut vacuum permittivity. When the thickness is set to zero, the substrate is assumed to completely fill the half-space below the extraction area.

This entry sets, and is set by, the SubstrateThickness variable.

FcPlaneBloat
This entry contains a length, in microns. If nonzero, horizontal dielectric/vacuum interface panels will extend outside of the area of interest (AOI, see 16.17.1) along the top surface of the substrate. The extension distance is the FcPlaneBloat distance.

When the SubstrateThickness is nonzero, the substrate bounding box, which is the AOI, will be bloated by this value before writing of the substrate bottom and side interface panels to the list file. This will move the abrupt dielectric change at the substrate edge away from the area of interest.

If the SubstrateThickness is zero the FcPlaneBloat distance should be large enough to represent ``infinity'', but making it too large will slow down computation. The model is approximating the entire half-space filled with substrate dielectric material.

This entry sets, and is set by, the FcPlaneBloat variable.

SubstrateEps
This entry supplies the relative dielectric constant asssumed for the substrate. This sets, and is set by, the SubstrateEps variable.

FcUnits
This is an option menu which is used to set the length units used in files produced by the interface. Choices are meters, centimeters, millimeters, microns (the default), inches, and mils. The selection, if not the default, will set the FxUnits variable. Similarly, setting the variable with the !set command will update the state of the menu. The choice currently in effect will be applied when input files are generated. The choice of units will not affect the computed capacitance.

The lower half of the page allows one to crudely refine the raw panels while being written to the list file. This is specifically for FasterCap-WR, which requires refined panelization for accuracy. The FasterCap program does not require external refinement, which is a major advantage. In fact, the refinement provided here should not be used with FasterCap, as it may interfere with FasterCap's refinement.

The refinement is ``crude'' due to each refined panel being approximately the same size. If the size is small enough, sufficient spatial resolution for accurate capacitance calculation is achieved. This resolution is needed along edges, and at corners, where there are strong field gradients, but is gross overkill for most areas. Since the solving time is related to the total number of refined panels, this type of refinement is very inefficient with respect to memory use and execution speed.

The refinement works as follows. First, the interface computes the total area of all conductor and dielectric raw panels that would be output to the list file. This area is divided by the FcPanelTarget number provided by the user. This is a number approximating the total refined panel count that FastCap-WR will need to process. The solution time should be approximately the same for the same panel count, independent of the actual geometry. The square root of the divided area is used when writing the panels to the list file. The raw panels are subdivided so that no panel edge is longer than this value.

A number like 10000 is probably about right for the FcPanelTarget in providing decent accuracy in a reasonable execution time. Larger numbers provide more accuracy, but require larger files and have longer solution time. The list file will contain a line for each refined panel. The entry area will take numbers up to 1e6, which is probably unreasonable for a normal computer.

Enable
This check box will enable or disable the refinement. This should not be active when using FasterCap. When pressed, the FcPanelTarget entry will become un-grayed, and internally the FcPanelTarget variable will be set to the number shown in the FcPanelTarget entry area. When the Enable button is set inactive, the FcPanelTarget variable is unset. The Enable button state will reflect whether or not the FcPanelTarget variable is set.

FcPanelTarget
This entry area is seensitive only when the Enable check box is checked. It tracks the value of the FcPanelTarget variable, which can be set to a real value of 1e3 - 1e6. This will be the approximate number of refined panels generated in the list file.