Research On The Effective Permittivity And Optimum Design Of Absorbing Coating With Core-shell Type Inclusions

In this paper, we have done research on the effective permittivity of ellipsoid inclusions and spherical core-shell type inclusions, using the method of micromechanics theory; sequentially optimized design of absorbing coating.First, the problem of electromagnetic field of ellipsoid type particle is studied, and effective permittivity forecasting formula of this particle is developed. Base on the research, the effect of particle shape on effective permittivity is gained.Using the method of micromechanics theory and the finite element method, the problem of electromagnetic field of spherical core-shell type particle is studied and effective permittivity forecasting formula of this particle is induced; the forecasting results is confirmed by the finite element method; the effect of material parameter and geometry parameter on the effective permittivity is studied.Base on the effective permittivity forecasting formula of spherical core-shell type inclusions, the theory frame of optimum design of absorbing coating is constructed; the optimization of single layer and double layers is done.The study results display: the particle shape trends to needle more, the effective permittivity is bigger when the volume of particle is the same. The particle shape trends to penny more, the effective permittivity is bigger when the volume of particle is the same. The dimension of particle doesn't affect the effective permittivity when the shape of particle is equal.On condition that the volume of particle is equal, the effective permittivity of penny shape particle is the biggest, that of the needle shape is second, and the spherical shape is the last.When the thicker of shell is constant and the radius of core is bigger, the effective permittivity is less. The effective permittivity will change acutely when the thicker of shell is close to the radius of core; with the radius of core increasing, the effective permittivity of core-shell type particle will approach that of no shell type particle.The results of optimization show: it will increase the coatings' ability of absorbing greatly if the thickness and the electromagnet parameters of every layer are matched properly.