# Defining a Dielectric Medium

Define a lossy frequency-independent dielectric with a relative permittivity ( ${\epsilon }_{\text{r}}$ ) = 5.6 and a dielectric loss tangent ( $\mathrm{tan}\delta$ ) = 0.0041 to be used as the patch substrate.

1. Open the Create Dielectric Medium dialog using one of the following workflows:
• On the Construct tab, in the Define group, click the  Media icon. From the drop-down list, click the  Dielectric icon.
• On the model tree, a right-click context menu is available on Media. From the list, click Dielectric Medium.

Two variables (ceramic_epsR and ceramic_tanD) were added to the model to define the dielectric.

1. Set the Relative permittivity ( ${\epsilon }_{\text{r}}$ ) to ceramic_epsR.
2. Set the Dielectric loss tangent ( $\mathrm{tan}\delta$ ) to ceramic_tanD.
3. Set the Label to Ceramic.
4. Click Create to create the dielectric and to close the dialog.
Note: In the model tree, the defined dielectric is displayed under Dielectric. CADFEKO assigns a colour to each medium randomly but the colour may be changed by using the Change Display Colour right-click context menu option.