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The antenna characteristics of a hemispherical Luneburg lens with a flat screen on the lens side opposite to the position of the feed are studied. The hemispherical geometry of the lens allows the lens to be effectively used in the scan mode. In the scan mode of the antenna, it is possible to choose the shape and parameters of the radiation pattern depending on the position of the feed.

Excitation of the Luneberg lens by an arc antenna array of open-ended rectangular waveguides forming the H10 wave is studied. Technical limitations imposed on the array of primary feeds in order to form the sum and difference operating modes of the antenna system are discussed.

The paper focuses on solving the problem of diffraction of a linear polarization electromagnetic wave on multilayer bodies of a spherical shape, i.e. a metal sphere with a dielectric cover and Luneberg lens. For this purpose tensor Green function method was used. Within the research we described the electrodynamic system verifying the expressions obtained for the calculation of electromagnetic fields. Furthermore, we compared the obtained results of calculations with the results of simulation of a similar problem in the software package ANSYS HFSS . Finally, we estimated the computational burden and computing time for solving the problem in two ways

Application peculiarities of the Green’s functions method for Cartesian, cylindrical and spherical coordinate system are under consideration. Layered magneto-dielectric structures with arbitrary extraneous electric and magnetic currents are investigated. The equivalent circuit approach is applied for layered structures description. Transmitting matrices are used for wave propagation modelling in each layer and through boundaries between layers. It is shown that the boundary transmitting matrix for flat and spherical structures is equal to the unit matrix. Different kinds of loads are used for region boundaries modelling. Proposed approach with transmitting matrices allows one to develop universal algorithms with common modules for solution of electromagnetic problems such as wave excitation and propagation, antennas radiation and scattering associated with flat, cylindrical and spherical structures of any number of layers, arbitrary permittivity and permeability.

The method of Green’s functions for layered magneto-dielectric structures with arbitrary extraneous electric and magnetic currents is described. Application peculiarities of the method for Cartesian, cylindrical and spherical coordinate system are under consideration. The equivalent circuit approach is applied for layered structures description. Transmitting matrices are used for wave propagation modelling in each layer and through boundaries between layers. It is shown that the boundary transmitting matrix for flat and spherical structures is equal to the unit matrix. Different kinds of loads are used for region boundaries modelling. Suggested method with transmitting matrices allows one to develop universal algorithms with common modules for wave propagation, antennas radiation and scattering problems associated with flat, cylindrical and spherical structures of any number of layers, arbitrary permittivity and permeability.

A hemispherical Luneburg lens antenna with an air gap between the lens body and circular conducting screen is under consideration. Reflected rays create a directional radiation from the initial weakly directional irradiator. Suggested antenna structure decreases considerably the overall dimensions and weight of lens antennas. The influence of conducting screen size, the air gap and the lens radius on radiation antenna pattern is analyzed. It is noted that by adjusting the air gap the antenna back radiation level is changed. The scanning mode of the hemispherical Luneburg lens antenna with a conducting screen is investigated. The beamwidth, sidelobe level, directivity and scanning angle are calculated and compared. Radiation patterns of axial and scanning mode are shown.

Luneburg lens antenna radiation fields are calculated with Green's functions of spherical and cylindrical layered structures. Electric field components of spherical and cylindrical Luneburg lenses excited by linear and circular polarized incident field are analysed. Dipole, slot and aperture antennas are described by electric and magnetic extraneous currents. Radiation patterns of cylindrical and spherical Luneburg lens are analysed. Co-polarized and cross-polarized field radiation patterns are shown. The proposed method significantly reduces the computing time for multi-layered lenses in comparison with the most commonly used in antenna design. The first step antenna structure optimization may be performed for a shorter time. The results may be used as the first approximation for Ansys HFSS and other software.

Luneburg lens antenna radiation fields are calculated with Green's functions of spherical and cylindrical layered structures. Electric field components for Luneburg lenses excited by a linear and circular polarized antenna are analyzed. Co-polarized and cross-polarized field radiation patterns are shown. Reflection from the lens, losses in the lens material, spillover and polarization loss are taken into account for antenna gain calculation. The proposed method significantly reduces computing time for multilayered lens in comparison with the most commonly used in antenna design. © 2015 Radio Society (Mauritius).

Electromagnetic absorbers are often used to reduce radar echoes, for heat protection, to suppress interference from enclosures. For many applications the absorbers must by conformal to surfaces. The absorber is composed of layers of lossy materials. Mores complex designs in use today are the frequency selective surfaces (FSSs). (5 pages)

Linear and circular polarized waves scattering on spherical homogeneous and layered bodies with negative refraction index are studied. The wave excitation and diffraction analysis is based on a new universal representation of Green's tensors for composite spherical bodies. Scattering waves' behaviour is analyzed.

With use of universal representation Green?s tensors for composite spherical bodies, we obtained the solution for number of actual problems of electromagnetic excitation and diffraction. In [1] results of research of influence of model of a head of the person on characteristics of radiation of the antenna of the mobile phone are given. In [2] shielding disseminating properties of a thin semiconducting shell were investigated.