The Effective Permittivity of an Anisotropic Composite of Spheroidal Particles in a Dielectric Matrix

https://doi.org/10.1134/S1063785022040058

The concentration dependences of the effective permittivity have been obtained for an anisotropic composite consisting of a dielectric matrix filled with codirectional particles in the form of oblate or prolate ellipsoids of revolution (spheroids). The calculation has been made by solving numerically a system of coupled quadratic and integral equations obtained using the rigorous modification of the quasi-static Bruggeman theory. It is shown that the traditional simplified modification of the Bruggeman theory, which is widely used for calculating anisotropic composites, leads to errors of different signs for electromagnetic waves of the longitudinal and transverse polarizations relative to the spheroid axes. The dependences of the errors on the particle concentration are nonmonotonic and extrema observed in them can exceed 100%. The positions and values of the extrema depend strongly on the ellipticity of particles and the contrast of their permittivity with that of the matrix.