Dielectric behaviour of composite media

The loss angle δ is used to characterize the dielectric properties of inhomogeneous materials, in the framework of percolation theory. We have shown that δ takes the universal value δ = πs/2(s + t) at the percolation threshold (p = pc), and low frequency (ε → 0), where s and t are the exponents of static electrical properties. We also present calculations of the frequency-dependent electric constant, based on hierarchical lattices, the transfer matrix method, and the effective medium theory. The high frequency regime is investigated in the case where the conductivity of the conducting phase is frequency dependent.