arXiv subjects

Constantin Simovski

Publications and source records attributed to Constantin Simovski.

43 records · Page 3Linked to original sources

arXiv2007

Magnification of Subwavelength Field Distributions at Microwave Frequencies Using a Wire Medium Slab Operating in the Canalization Regime

Magnification of subwavelength field distributions using a wire medium slab operating in the canalization regime is demonstrated using numerical simulations. The magnifying slab is implemented by radially enlarging the distance between adjacent wires, and the operational frequency is tuned to coincide with the Fabry-Perot resonance condition. The near-field distribution of a complex-shaped source is canalized over an electrical distance corresponding roughly to $3λ$, and the distribution details are magnified by a factor of three. The operation of the slab is studied at several frequencies deviating from the Fabry-Perot resonance.

physics.class-ph↗

arXiv2006

Near-field enhancement and sub-wavelength imaging in the optical region using a pair of two-dimensional arrays of metal nanospheres

Near-field enhancement and sub-wavelength imaging properties of a system comprising a coupled pair of two-dimensional arrays of resonant nanospheres are studied. The concept of using two coupled material sheets possessing surface mode resonances for evanescent field enhancement is already well established in the microwave region. This paper shows that the same principles can be applied also in the optical region, where the performance of the resonant sheets can be realized with the use of metallic nanoparticles. In this paper we present design of such structures and study the electric field distributions in the image plane of such superlens.

physics.optics↗

arXiv2005

Experimental demonstration of sub-wavelength image channeling using capacitively loaded wire medium

In this letter we experimentally demonstrate a possibility to achieve significant sub-wavelength resolution of a near-field image channeled through a layer of an electromagnetic crystal. An image having radius of $λ/10$ has been realized using an electrically dense lattice of capacitively loaded wires. The loading allows to reduce the lattice period dramatically so that it is only a small fraction of the free-space wavelength. It is shown that losses in the structure only decrease the total amplitude of the image, but do not influence the resolution.

cond-mat.mtrl-sci↗

arXiv2005

On Artificial Magneto-Dielectric Loading for Improving the Impedance Bandwidth Properties of Microstrip Antennas

In the present paper we discuss the effect of artificial magneto-dielectric substrates on the impedance bandwidth properties of microstrip antennas. The results found in the literature for antenna miniaturization using magnetic or magneto-dielectric substrates are revised, and discussion is addressed to the practically realizable artificial magnetic media operating in the microwave regime. Using a transmission-line model we, first, reproduce the known results for antenna miniaturization with non-dispersive material fillings. Next, a realistic dispersive behavior of a practically realizable artificial substrate is embedded into the model, and we show that frequency dispersion of the substrate plays a very important role in the impedance bandwidth characteristics of the loaded antenna. The impedance bandwidths of reduced size patch antennas loaded with dispersive magneto-dielectric substrates and high-permittivity substrates are compared. It is shown that unlike substrates with dispersion-free permeability, practically realizable artificial substrates with dispersive magnetic permeability are not advantageous in antenna miniaturization. This conclusion is experimentally validated.

physics.class-ph↗

arXiv2005

Improving antenna near-field pattern by use of artificial impedance screens

An antenna prototype utilizing artificial impedance surfaces to control the near field distribution is described. The antenna is a folded dipole placed above a finite-size artificial impedance surface. We have found that the field screening is most effective if the surface is a metal conductor. However, to achieve a reasonable value of the radiation resistance the dipole should be located far off the screen. If the surface is a magnetic wall, the antenna design is more compact, but the field behind the screen is large. Here we realize a compromise solution using an inductive surface of a moderate surface impedance, which allows realization of an effective near-field screen with still a reasonably low-profile design.

physics.class-ph↗

arXiv2005

Light-Weight Base Station Antenna with Artificial Wire Medium Lens

In this paper we study the possibility of utilizing a loaded wire medium as an artificial material for beam shaping element in base station antenna applications. The wires in the lattice are loaded with a proper capacitive impedance to come up with a structure effectively operating as a dielectric lens at the UMTS (Universal Mobile Telecommunications System) frequency range. It is proven with full-wave simulations that the interpretation of a finite size wire lattice as a dielectric lens is physically sound even with a moderate number of lattice periods. A prototype having a mechanically reconfigurable beam width is constructed and measured. It is shown that very promising performance can be achieved with a rather simple structure and a cheap manufacturing process.

physics.class-ph↗

arXiv2002

Waves and energy in chiral nihility

A model for a chiral material in which both the permittivity and permeability are equal to zero is discussed. Such a material is referred by us as a ``chiral nihility". It is shown that this exotic material can be realized as a mixture of small helical inclusions. Wave solutions and energy in such a medium are analyzed. It is shown that an extraordinary wave in chiral nihility is a backward wave. Wave reflection and refraction on a chiral nihility interface is also considered. It is shown that a linearly polarized wave normally incident onto this interface produces the wave of "standing phase" and the same wave in the case of oblique incidence causes two refracted waves, one of them with an anomalous refraction.

cond-mat↗