We present a novel theoretical approach for modeling the resonant properties of transmission through subwavelength apertures penetrating metal films. We show that cavity mode theory applies to an effective resonant cavity whose dimensions are determi
ned by the apertures geometry and the evanescent decay lengths of the associated diffracted waves. This method suggests a concrete physical mechanism for the enhanced transmission observed in periodic aperture arrays, namely it is the evanescently scattered light, localized in the near field of metal surface, which couples into the apertures. Furthermore, it analytically predicts the frequencies of peaks in enhanced transmission, the quality factor of the peaks, and explains their dependence on variation in the hole radius, periodicity, and the film thickness over a wide range of geometries. This model demonstrates strong correlation to simulation and existing results with a high degree of accuracy.
We explore the hybridization of fundamental material resonances with the artificial resonances of metamaterials. A hybrid structure is presented in the waveguide environment that consists of a resonant magnetic material with a characteristic tuneable
gyromagnetic response that is integrated into a complementary split ring resonator (CSRR) metamaterial structure. The combined structure exhibits a distinct hybrid resonance in which each natural resonance of the CSRR is split into a lower and upper resonance that straddle the frequency for which the magnetic materials permeability is zero. We provide an analytical understanding of this hybrid resonance and define an effective medium theory for the combined structure that demonstrates good agreement with numerical electromagnetic simulations. The designed structure demonstrates the potential for using a ferrimagnetic or ferromagnetic material as a means of creating a tunable metamaterial structure.
We use a numerical electromagnetic simulation software to investigate a filtering device consisting of a small dimensional microstrips embedded with a thin layer of ferromagnetic material and we compare our results to experimental results. We are abl
e to show good correlation of simulation versus experiment for the magnitude of insertion loss and phase shift. The microstrips considered have dimensions on the order of the skin depth of the conductor and hence the field distribution is not easily calculated by analytic methods. We show that numerical simulation methods provide an accurate means of characterizing these structures.
