Comparison of long-wavelength T-matrix multiple-scattering theory and size-dependent Maxwell-Garnett formula

Wave attenuation in a dielectric-in-dielectric composite is calculated using the long-wavelength T-matrix multiple-scattering theory and the size-dependent Maxwell-Garnett formula. Results obtained are first compared, and then followed by their comparisons with the experimental results and other theoretical results. An interesting observation made is that the size-dependent Maxwell-Garnett formula predicts monotonically increasing wave attenuation with increasing concentration of inclusions, whereas the computed results from the multiple-scattering theory theory and other formulas, together with the experimental results, indicate maximum wave attenuation at a certain concentration of inclusions. It is shown that the size-dependent Maxwell-Garnett formula gives good prediction of wave attenuation only up to inclusion concentration of about 2%, and the T-matrix multiple-scattering theory in the long-wavelength approximation gives good prediction of wave attenuation even beyond the inclusion concentration of 2%. (C) 1999 John Wiley & Sons, Inc.