# Further Information

The physical parameters ${\epsilon}_{r}{}^{\prime}$ and ${\epsilon}_{r}{}^{\prime \text{}\prime}$ correspond to the following equation, where represents the conductivity of the material.

$${\underset{\_}{\epsilon}}_{r}={\epsilon}_{r}^{\text{'}}-j\cdot {\epsilon}_{r}^{\text{'}\text{'}}={\epsilon}_{r}-j\frac{\sigma}{2\pi f{\epsilon}_{0}}$$