Modeling of Periodic Array of Cut-through Slits with Periodic Surface Conductivity at the Interfaces of an Anisotropic Medium

TL;DR

This paper develops an effective medium model for a periodic array of slits in a perfect electric conductor, incorporating anisotropic surface conductivity to accurately emulate both zeroth and higher diffraction orders, validated by full-wave simulations.

Contribution

It introduces a novel effective medium model with periodic surface conductivity capable of representing multiple diffraction orders in anisotropic slit arrays.

Findings

Model accurately predicts diffraction patterns including higher orders.

Effective parameters are derived by matching scattered waves.

Full-wave simulations confirm the model's validity.

Abstract

A periodic arrangement of one-dimensional slits carved in perfect electric conductor is investigated and an equivalent model based on the effective medium theory is derived. The proposed model is no longer fully homogeneous and features periodic surface conductivity on its upper and lower interfaces. 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 non-specular diffraction orders. The parameters of the equivalent model are found by comparing the scattered waves of the proposed model against those of the original structure obtained by invoking the rigorous mode matching technique based on the single mode approximation inside the slits. The proposed model is characterized by diagonal anisotropic permittivity and permeability tensors together with a periodic surface conductivity at the interfaces of the metallic grating and the ambient environment. The accuracy of the model is verified by the full-wave simulations. The proposed approach might be useful for devising applications which work based on the characteristics of higher Floquet orders.