Modeling of Periodic Array of Cut-Through Slits With Sinusoidal Surface Conductivity at the Interfaces of an Anisotropic Medium

A periodic arrangement of 1-D slits carved in a perfect electric conductor is investigated, and an equivalent model which features sinusoidal surface conductivity on its upper and lower interfaces is derived. Therefore, and in sheer contrast to all the previous attempts that were successful in mimicking only the zeroth-order diffracted waves, it is capable of emulating both specular and nonspecular diffraction orders. The accuracy of the model is verified by the full-wave simulations. The proposed model is used to study the sharp Fano-type extraordinary transmission resonances arising in the structure. The transmission spectrum near these resonances is derived in terms of Fano resonance parameters. Furthermore, our model is used to explain the plasma-like behavior of the cut-through metallic slits in terms of the band bending caused by the periodicity of the surface conductivity. The analysis and design of applications which are devised based on the characteristics of higher Bloch orders can also be facilitated by this model.