A comparative study of the effective propagation constant in a random medium containing coated dielectric particles

Studies of the propagation and scattering of waves in random media containing dielectric particles have previously been made with applications to remote sensing technology and material science. The particles in natural geophysical terrain and in composite materials consist of different constituents. Therefore it is important to have a medium model containing dielectric particles consisting of two layers with different materials. This model may be used to study waves propagating in media such as melting snow, wet snow, soil moisture and composite materials with coated granules. In this paper, we treat the medium model whose coated spherical particles are randomly distributed. The effective propagation constant (K_eff) in a random medium containing coated dielectric particles has been analyzed by conventional methods: EFA (effective field approximation, Foldy´s approximation), QCA (quasicrystalline approximation) and QCA-CP (QCA with coherent potential). These methods, however, have been indicated to become invalid for particles coated with a material having high dielectric constant; we have thus presented a new method valid for them. This paper compares K_eff of our method with those of the conventional methods by changing the volume fraction and the structure of particles. As a result, our method is shown to be more powerful for the analysis of K_eff