Scott Gurst wrote:
>
> The crosstalk equations in section 5.7.2 of IPC-D-317A use the variable (r (Mu sub-r) in the equations for A2 and B2.  I can't seem to find a definition for these variables in the document.  Does anyone know what these are?

--
Mu sub-r is the relative permeability. It is very close to one for most
materials, EXCEPT for ferrous materials (stuff like iron, steel, etc.).
Think of it like you think of relative permittivity (dielectric
constant). It is a material property. In both cases, the r subscript
denotes relative. Relative to what, you say? Relative to free space (mu
sub-zero or epsilon sub-zero). If you are working with "conventional"
printed circuit boards (no ferrous materials present) and trying to do
crosstalk calculations, my suggestion would be to set it to one.


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