Abstract: By using computer controlled ultra-low frequency dielectric spectrometer and HP4124A impendence analyzer,
we measured the frequency domain dielectric spectrum of SrTiO₃ ceramics in the frequencies from 10^-4Hz to 10⁵Hz. The complex dielectric constants
obtained can be well extracted into the summation of two components. The lower frequency one can probably attribute to the motion of space charges
in grain boundaries, the higher frequency one can attribute to that within the grains. Further, real permittivity of the latter component changes to be
below zero at high frequencies. It indicates that frequency domain method is not a proper method for describing dielectric spectroscopy, while the
experimental results can not be explained by traditional dielectric polarization theory.

Key words: wide frequency range, ultra-low frequency, dielectric spectroscopy, SrTiO₃