CST2013: Material Parameters: default - Conductivity

Modeling: MaterialsNew/EditNew MaterialConductivity

Edit Object Properties (navigation tree: Materials:material1PropertiesConductivity)

This is a dialog page of the Material Parameters dialog box. It is only visible for "Default" and "High Frequency" material sets.

On this dialog page, the electric and magnetic conductivity characteristic of the current material may be specified. This is possible by defining either the conductivity value or the tangent delta value of the material. For dielectric losses, special tangent delta models are offered to enable a realistic material modeling. All input parameters are also available for an anisotropic material type.

Note that it is not possible to define a conductivity or tangent delta value for a previously defined dispersive material.

The introduction of losses leads to complex material parameters possessing both a real and an imaginary part. For all possible loss definitions on this page, the real part is always determined by the permittivity or the permeability value, respectively, on the Material Parameter - General page. If the real part of the complex material model is frequency dependent, the defined value is only correct for one frequency point, namely the specified tangent delta frequency (constant fit) or the solver center frequency (dispersion fit).

Note: Defining parameters for constant electric/magnetic conductivity value then they can be used with sensitivity analysis (see Sensitivity Analysis for more information).

Electric conductivity frame

Electric conductivity: Activating this radio button defines a conducting material based on the model of a constant electric conductivity value.

Nonlinear: This checkbox enables setting of the nonlinear electric conductivity. Button Properties... opens the Nonlinear Electric Conductivity dialog, where the E(J)-curve can be defined.

Tangent delta electric: Activating this radio button offers the possibility to define different loss models based on electric tangent delta values.

Specification: Three different electric tangent delta specifications are available:

Const. Conductivity: This model corresponds to a material possessing a constant conductivity as mentioned above, but is defined by the input of an electric tangent delta value given at a specific frequency.

Const. fit tan delta:  This specification is based on a pole-zero dispersion model, defined again by the input of an electric tangent delta value given at the defined frequency and by the model order. The first order corresponds to a Debye dispersion whereas higher order models are specifically developed to fit a broadband constant imaginary part of the permittivity. They are particularly suitable for low losses (low tangent delta value) materials. As mentioned above, at this frequency point the real part of the permittivity equals the epsilon input on the Material Parameter - General page. Please note that a perfectly constant tangent delta does not exist in reality; however, the broadband behavior of this formulation represents an almost constant tangent delta curve.

Dispersion fit tan delta:  The dispersion fit is based either on a constant conductivity or a General 1st order model. Now more than one tangent delta value may be defined for different frequency points by pressing the Dispersion List… button. To each frequency point a weight is assigned in order to direct the interpolation algorithm and to enforce the result quality. Again, the real part of the permittivity is given by the epsilon input on the Material Parameter - General page. Please note that due to the frequency dependent material behavior the values correspond only at the center frequency.

Magnetic conductivity frame

Magnetic conductivity: Activating this radio button defines a conducting material based on the model of a constant magnetic conductivity value.

Tangent delta magnetic: Activating this radio button enables the input of a magnetic tangent delta value given at specific frequency.

Specification: Three different magnetic tangent delta specifications are available:

Const. Conductivity: This model corresponds to a material possessing a constant conductivity as mentioned above, but is defined by the input of a magnetic tangent delta value given at a specific frequency.

Const. fit tan delta: This specification is based on a pole-zero dispersion model, defined again by the input of a magnetic tangent delta value given at the defined frequency and by the model order. The first order corresponds to a Debye dispersion whereas higher order models are specifically developed to fit a broadband constant imaginary part of the permeability. They are particularly suitable for low losses (low tangent delta value) materials. As mentioned above, at this frequency point the real part of the permeability equals the mue input on the Material Parameter - General page. Please note that a perfectly constant tangent delta does not exist in reality, however, the broadband behavior of this formulation represents an almost constant tangent delta curve.

Dispersion fit tan delta: The dispersion fit is based either on a constant conductivity or a general 1st order model. Now more than one tangent delta value may be defined for different frequency points by pressing the Dispersion List… button. To each frequency point a weight is assigned in order to direct the interpolation algorithm and to enforce the result quality. Again the real part of the permeability is given by the mue input on the Material Parameter - General page. Please note that due to the frequency dependent material behavior the values correspond only at the center frequency.

Frequency range frame

Fmin/Fmax: These text fields are for information purposes only. They show you the minimal and maximal chosen frequency. To change these values you may go into the  frequency range settings in the main menu under Solver Frequency....