# SK Card

This card defines a skin effect, ohmic losses, dielectric sheet, characterised surface definition, arbitrary user defined impedance boundary condition on wire segments and surface elements or a dielectric surface impedance approximation. Layered dielectrics can also be defined.

In the Home tab, in the Define group, click the   Media icon. From the drop-down list select the  Losses (SK) icon.

## Parameters:

Affect all structures with label
The label to which the skin effect is applied is specified. All mesh elements with this label are assigned the skin effect.
Assume ideal conductivity
Ideal conductivity is assumed as if no SK card is specified for this label. All other parameters are ignored.
High frequency approximation skin effect
Apply the high frequency approximation skin effect to structures with the specified label.
Static approximation skin effect
Apply the static (ohmic losses) approximation skin effect to structures with the specified label.
Exact expression for the skin effect (including surface roughness)
Apply the exact expression for the skin effect (which includes the effects of surface roughness) to metallic surfaces and/or wires with the specified label.
Triangles as thin isotropic dielectric sheet
Treat metallic triangles with the specified label as thin isotropic dielectric layers (possibly consisting of multiple layers).
Triangles as thin anisotropic dielectric sheet
Treat metallic triangles with the specified label as thin anisotropic dielectric layers (possibly consisting of multiple layers).
Triangles using a characterised surface definition
Treat triangles with the specified label as a characterised surface (a surface defined by transmission and reflection coefficient data).
User defined surface impedance
Treat wire segments and surface elements with the specified label as an arbitrary user defined complex surface impedance.
Dielectric surface impedance approximation
Treat homogeneous dielectric regions in free space with the specified label as a dielectric surface impedance approximation.

## Recommendations for Choosing the Label(s)

It is not recommended to set the same label for both triangles and segments with Affect all structures with label. Separate labels and a unique SK card for each label should be used. In addition all wires with the label Affect all structures with label must have the same radius. If this is not the case a unique label must be created for each radius.
Note: The skin depth is given by ${\delta }_{skin}=\sqrt{\frac{2}{\omega \mu \sigma }}$ , where the radial frequency is $\omega =2\pi f$ and the permeability is $\mu ={\mu }_{r}{\mu }_{0}$ .