Bounds for the complex dielectric constant of a two-component composite material

Rigorous bounds are derived for the bulk effective complex dielectric constant Kₑ of a two-component composite medium in two cases: (a) when only the complex dielectric constants of the two components are known and (b) when, in addition to that, also the volume fractions are known. The bounds have a very simple geometric representation in the complex Kₑ plane. From these bounds, some useful conclusions are drawn with respect to measured values of these constants in various types of composites.