Research of antenna complexes using chiral metamaterials and fractal geometry of radiators for MIMO systems

The paper considers an artificial chiral metamaterial created on a homogeneous container basefrom foamed dielectric, in which flat conducting S-shaped microelements are evenly placed and arbitrarily oriented. To describe the metamaterial, a particular mathematical model was constructed that takes into account chirality, dispersion, and heterogeneity of the structure. The Maxwell Garnett model was used to account for heterogeneity. To take into account the dispersion of the chirality parameter, the Condon model known from the theory of optically active media was used. The partial domain method was used to solve the problem of the incidence of a plane electromagnetic wave of linear polarization on a planar layer created on the base of the investigated chiral metamaterial. The solution of the problem was reduced to an inhomogeneous system of linear algebraic equations for unknown reflection and transmission coefficients, taking into account the cross-polarization of the electromagnetic field. An analysis of the numerical results showed that the structure has pronounced frequency selective properties, in particular, as in the case of chiral metamaterial based on three-dimensional conductive elements, discrete frequencies were determined at which the structure is transparent to microwave radiation. Chiral metamaterial based on C-shaped microelements can be used to create narrow-band frequency-selective microwave energy concentrators of planar type.

Investigation of the microwave chiral metamaterial based on a uniform set of C-shaped conductive inclusions

Buchnev

Kushnir²,

Осипов³

et al. 2023

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

Buchnev

Осипов

2023

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 DrudeLorentz 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.

Modeling of electromagnetic wave reflection from wet soil taken into account of dispersion, heterogeneity and surface roughness

Panin,

Osipov

2024

Background. Taking into account temperature, soil composition, surface roughness and the dependence of effective dielectric constant on frequency allows a more accurate assessment of soil moisture and other important parameters, which can be used in various fields such as agriculture, geology, ecology and hydrology. Aim. In this work, we calculate the reflection of a linearly polarized electromagnetic wave from wet soil, taking into account such physical factors as heterogeneity of soil structure, surface roughness and dispersion. Methods. Based on a heterogeneous mathematical model of wet soil, taking into account the dispersion of the dielectric constant of water and surface roughness, expressions are derived for the complex reflection coefficients of electromagnetic waves of vertical and horizontal polarization. Results. The model of loose wet soil with the standard deviation of roughness on the surface was chosen as the object of study. An analysis of the frequency and angular characteristics of the modules of the reflection coefficients was carried out at a fixed level of soil moisture. Conclusion. The data obtained as a result of the calculations is a valuable tool for further improving methods of remote sensing of the Earth and contributes to the development of new technologies for monitoring soil parameters using unmanned aerial vehicles, which opens up prospects for more accurate and efficient analysis of the state of land resources and ecosystems.