PROPAGATION IN RANDOM-MEDIA - CALCULATION OF THE EFFECTIVE DISPERSIVEPERMITTIVITY BY USE OF THE REPLICA METHOD

In this paper we use the replica method together with a variational me thod in order to study the propagation of a wave traveling in a disord ered composite. We compute the effective permittivity tenser, which ta kes into account the effects of spatial dispersion. Our calculation is not perturbative in the frequency, and we obtain a self-consistent fo rmula for the longitudinal and transverse parts of the permittivity te nser applicable to the whole range of frequency. Our result appears as a self-consistent version of the usual weak-disorder expansion and th us recovers all weak-disorder results. We have checked that the soluti on to the self-consistent equations is correct in the limits of high a nd low spatial frequency.