Numerical computation of effective electromagnetic properties for dielectric honeycombs

Abstract

The finite element numerical computation and the retrieval technique are adopted to evaluate the effective electromagnetic properties of the regular periodic dielectric honeycomb cores under the periodic boundary conditions. And then we compare the effective permittivities of dielectric honeycomb unit cells with the different configurations and the same dielectric materials. The size effect of dielectric honeycomb unit cells on the effective permittivity is pointed out. To simulate the periodic boundary conditions, the PEC (Perfect Electric Conductor) and PMC (Perfect Magnetic Conductor) are imposed on the unit cells in the different periodic dielectric honeycombs. Moreover, the requirement of effective media theory is satisfied that the unit cell dimension is the factor 6 smaller than the center wavelength at least. So the refractive index and the wave impedance are obtained by the scattering parameter retrieval method. On this basis, the effective permittivity and permeability of periodic electric honeycombs are calculated. Numerical results show that the configuration and size of dielectric honeycomb unit cells have the obvious influences on the effective electromagnetic properties. And the effective electromagnetic properties of the periodic dielectric honeycomb cores have the obvious in-plane size effect. With increasing infinitely the number of unit cells, the effective permittivity of dielectric honeycombs trends to the homogenization value. The research demonstrates that the size effect has the same action on the effective electromagnetic and mechanical properties of periodic honeycomb structures. It provides the analyzing foundation for the multifunctional design and application of honeycomb sandwich structures in the special fields (radomes, stealth structures and so on).