Accurate Characterization of Electromagnetic Band-Gap Structures

In this paper, electromagnetic band-gap (EBG) structures are accurately characterized using a free-space method. The field transmission and reflection parameters are exploited to determine the effective material parameters both inside and outside the band-gap regions of the EBG structures. The electromagnetic (EM) properties of the effective refractive index, effective wave impedance, effective permittivity, and effective permeability at multiple band-gap regions are derived from a single scattering computation. The derived phase and attenuation constants correctly define the boundaries of the band-gap region and the level of attenuation within the band gap. Deviations in the incidence angle from the normal direction alter the EM properties; hence, the operating bandwidth of the band-gap region is as expected due to the inherent structure anisotropy of the unit cells.