  The homogenization of a composite material comprising three isotropic
dielectric materials was investigated. The component materials were randomly
distributed as spherical particles, with the particles of two of the component
materials being coupled to form dimers. The Bruggeman and Maxwell Garnett
formalisms were developed to estimate the permittivity dyadic of the
homogenized composite material (HCM), under the quasi-electrostatic
approximation. Both randomly oriented and identically oriented dimers were
accommodated; in the former case the HCM is isotropic, whereas in the latter
case the HCM is uniaxial. Representative numerical results for composite
materials containing dielectric--dielectric dimers demonstrate close agreement
between the estimates delivered by the Bruggeman and Maxwell Garnett
formalisms. For composite materials containing metal--dielectric dimers with
moderate degrees of dissipation, the estimates of the two formalisms are in
broad agreement, provided that the dimer volume fractions are relatively low.
In general, the effects of intradimer coupling on the estimates of the HCM
permittivity are relatively modest but not insignificant, these effects being
exacerbated by anisotropy when all dimers are identically oriented.
