In this work the values of the real part $\epsilon^{\prime}$ and imaginary part $\epsilon^{\prime\prime}$ of the complex dielectric constant $\epsilon$ of some mixtures of liquids are determined at the frequency of 5 GHz (some mixtures being polar with non-polar, and others polar with polar) according to the variation of percentage of their volume. From the experimental results it seems it can be deduced: 1) that the dipoles preserve freedom of movement at such very high frequencies; 2) that the $\epsilon^{\prime\prime}$ have a behaviour like that of the conductivity, if this is pre-eminent, or like that of viscosity, if the conductivity is effectively very small.