The Radius Box
To the right of the Symmetry Bar is the Radius Box. This allows the
user to specify how the radii of the mesh segments are calculated. By
default the radii are calculated from the maximum segment length
divided by 2π — the rule of equal surface area. (This will ensure
that the wiregrid under consideration models a conducting surface area
with a high degree of accuracy.) The user is allowed a choice between:
- Using the ``segment length'' (the default) as the criterium for
calculating the radii of the segments. If this option is chosen, the wire radii in the mesh will vary according to the length of each specific segment (that is radius = length of segment/2π). The radius-to-segment-length-ratio will thus be the same throughout the mesh, and unacceptable values for this ratio will be avoided. However, the
rule of equal surface area will not necessarily be satisfied.
- Using the ``nominal length'' as the criterium for calculating the radii of the segments. If this option is chosen, all wire radii in the mesh will be the same (and will satisfy the rule of equal surface area — radius = maximum segment length/2π).
This could however lead to a situation where unacceptably radius-to-segment-length-ratios are encountered.
- Using a ``fixed'' radius value (radius = fixed radius
specified by user) throughout the model — except for the
wires (two-noded major elements) for which distinct radius values have
been specified. This option can be useful when exceptionally long thin
``major elements'' with short sides — much shorter than the maximum
segment length — have been specified. Choosing a (relatively thin)
fixed radius value throughout the mesh will then avoid overlapping
wires for these ``special'' elongated major elements. However, the rule
of equal surface area will almost certainly not be satisfied if this
option is chosen.