Frequency Dependent Material Properties

The properties of some materials vary with the frequency of the field excitation. This frequency dependence is often linear within a certain frequency range and constant outside of the frequency range, as shown below:

where

• epsr_lower is the relative permittivity of a material below the frequency range 20 - 50 GHz.
• epsr_upper is the relative permittivity of a material above the frequency range 20 - 50 GHz.
• f_lower is the lower frequency, below which the material property is constant.
• f_upper is the upper frequency, above which the material property is constant.

Frequency-dependent materials are appropriate for problems solved using a discrete or interpolating sweep.