Investigation of the electromagnetic properties of a transverse insert based on a planar layer of a chiral metamaterial in a rectangular waveguide

The paper considers the solution of the problem of diffraction of the fundamental wave of a rectangular waveguide H10 on a planar transverse insert based on a chiral metamaterial created on the thin-wire conducting helices. To describe the chiral layer, a particular mathematical model is constructed that takes into account the properties of heterogeneity and dispersion of the permittivity and the chirality parameter of the artificial media. The well-known in physics model of Maxwell Garnett was used to take into account the heterogeneity property. To take into account the permittivity dispersion the Drude-Lorentz formula was applied and for the chirality parameter was used the Condon formula. The problem of diffraction of the rectangular waveguide main wave on a planar layer of a chiral metamaterial was solved by the partial regions method and was reduced to a system of linear algebraic equations for unknown reflection and transmission coefficients. It is shown that in the presence of a transverse chiral layer in the waveguide structure, a wave of the H01 type cross-polarized with respect to the main one arises. An analysis of the frequency dependences of the moduli of the reflection and transmission coefficients of the fundamental H10 and cross-polarized H01 showed that in some narrow frequency intervals in the single-mode gap, situations arise when the fundamental wave type is replaced from H10 to H01 near resonant frequencies. The transmission line under consideration can find application in the creation of frequency selective filters and polarization converters in the microwave range.