HFSS15: Djordjevic-Sarkar Model Parameter Calculation

The model parameters can be calculated if the following information about the material is known:

• DC conductivity, s_DC (optional; default value is 0)

• DC permittivity, e_DC (optional; you have to choose the default. See below)

• A triplet of real numbers, consisting of

• the measurement frequency w₁

• the real permittivity e₁ at this frequency

• the loss tangent tan d₁ at this frequency

We know the imaginary part of e(w₁) = -e₁. tand₁. Therefore we get,

and so

The following equation for the real part also holds:

Inserting the above expression allows us to solve for the high-frequency permittivity:

Check the computed value of lower transition frequency to make sure that it is much less than the measurement frequency. If not, raise the DC permittivity; this will reduce the value of the lower transition frequency. If you do not know the DC permittivity value, you may choose one yourself to satisfy the condition: