LONG-WAVELENGTH ABSORPTION IN COMPOSITES

The absorption of long-wavelength radiation in ceramic-metal composites is calculated within the electrostatic approximation. The interaction of nearest-neighboring inclusions is used to estimate the asymptotic and resonant behavior of the effective polarizability of the composite and thus to determine the long-wavelength absorption properties. A critical wavelength is introduced related to the density of the composite or the separation of neighboring inclusions. At wavelengths much longer than the critical wavelength, the absorption is similar to that for isolated inclusions; at shorter wavelengths there is considerable enhancement. The behavior of the polarizability is also related to the analytic structure (in particular the spectral representation and singularities) of the effective dielectric constant as a function of the permittivities of the constituent phases.