M. Sigalov

Errata to “Dual Frequency and Dual Circular Polarization Microstrip Nonresonant Array Pin-Fed From a Radial Line”

A new type of a dual frequency and dual circular polarization multilayer microstrip nonresonant antenna array for satellite communication is presented. The microstrip radiating elements in the array are arranged in concentric circles and fed through pins embedded in a radial line. The radial line is excited through a probe at its center. The microstrip array exhibits a dual frequency band of operation, low side-lobes in the radiation pattern, and high radiation efficiency (more than 65%) for both polarizations. The microstrip element has been designed using commercial software based on the method of finite integral time domain algorithm, and the feed network has been designed by a theoretical analysis. A prototype of the array has been built and tested. The agreement between the measured and numerical results is satisfactory.

Tellegen particles and magnetoelectric metamaterials

In 1948 Tellegen [Philips Res. Rep. 3, 81 (1948)] suggested that an assembly of the lined up electric-magnetic dipole twins can construct a new type of an electromagnetic material. Until now, however, the problem of creation of the Tellegen medium is a subject of strong discussions. An elementary symmetry analysis makes questionable an idea of a simple combination of two (electric and magnetic) dipoles to realize local materials with the Tellegen particles as structural elements. In this paper we show that in search of sources with local junctions of the electrical and magnetic properties one cannot rely on the induced parameters of small electromagnetic scatterers. No near-field electromagnetic structures and no classical motion equations for point charges give a physical basis for realization of sources with a local junction of the electrical and magnetic properties. We advance a hypothesis that local magnetoelectric (ME) particles should be physical objects with eigenmode oscillation spectra and noncla...

Magnetic-dipolar and electromagnetic vortices in quasi-2D ferrite discs.

Magnetic-dipolar-mode (MDM) oscillations in a quasi-2D ferrite disc show unique dynamical symmetry properties resulting in the appearance of topologically distinct structures. Based on the magnetostatic (MS) spectral problem solutions, in this paper we give evidence for eigen-MS power-flow-density vortices in a ferrite disc. Due to these circular eigen-power flows, the MDMs are characterized by MS energy eigenstates. It becomes evident that the reason for stability of the vortex configurations in saturated ferrite samples is completely different from the nature of stability in magnetically soft cylindrical dots. We found a clear correspondence between analytically derived MDM vortex states and numerically modeled electromagnetic vortices in quasi-2D ferrite discs.

Electric self-inductance of quasi-two-dimensional magnetic-dipolar-mode ferrite disks

An electric current flowing around a loop produces a magnetic field and hence a magnetic flux through the loop. The ratio of the magnetic flux to the electric current is called the (magnetic) self-inductance. Can there be a dual situation with a magnetic current flowing around a loop and producing an electric field and hence an electric flux through the loop? Following the classical electrodynamics laws an answer to this question should be negative. Nevertheless, special spectral properties of magnetic-dipolar modes in a quasi-two-dimensional ferrite disk show that there are the double-valued-function loop magnetic currents which may produce eigenelectric fields and hence eigenelectric fluxes through the loop. In this case one can definitely introduce a notion of an electric self-inductance as the ratio of the electric flux to the magnetic current. In this paper we show experimentally that in the magnetic-dipolar-mode ferrite disks there exist eigenelectric fluxes. These fluxes are very sensitive to the permittivity parameters of materials abutting to a ferrite disk. Dielectric samples above a ferrite disk with a higher permittivity than air confine the electric field closely outside the ferrite, thereby changing the loop magnetic currents and thus transforming the magnetic-dipolar-mode oscillating spectrum.

Microwave whirlpools in a rectangular waveguide cavity with a thin ferrite disk.

We study a three-dimensional system of a rectangular waveguide resonator with an inserted thin ferrite disk. The interplay of reflection and transmission at the disk interfaces together with a material gyrotropy effect, gives rise to a rich variety of wave phenomena. We analyze the wave propagation based on full Maxwell-equation numerical solutions of the problem. We show that the power-flow lines of the microwave-cavity field interacting with a ferrite disk, in the proximity of its ferromagnetic resonance, form whirlpool-like electromagnetic vortices. Such vortices are characterized by the dynamical symmetry breaking. The role of ohmic losses in waveguide walls and dielectric and magnetic losses in a disk are the subjects of our investigations.

Manipulating microwaves with magnetic-dipolar-mode vortices

There has been a surge of interest in the subwavelength confinement of electromagnetic fields. It is well known that, in optics, subwavelength confinement can be obtained from surface plasmon (quasielectrostatic) oscillations. In this article, we propose to realize subwavelength confinement in microwaves by using dipolar-mode (quasimagnetostatic) magnon oscillations in ferrite particles. Our studies of interactions between microwave electromagnetic fields and small ferrite particles with magnetic-dipolar-mode (MDM) oscillations show strong localization of electromagnetic energy. MDM oscillations in a ferrite disk are at the origin of topological singularities resulting in Poynting vector vortices and symmetry breakings of the microwave near fields. We show that new subwavelength microwave structures can be realized based on a system of interacting MDM ferrite disks. Wave propagation of electromagnetic signals in such structures is characterized by topological phase variations. Interactions of microwave fields with an MDM ferrite disk and MDM-disk arrays open a perspective for creating engineered electromagnetic fields with unique symmetry properties.

Effective chiral magnetic currents, topological magnetic charges, and microwave vortices in a cavity with an enclosed ferrite disk

In microwaves, a TE-polarized rectangular-waveguide resonator with an inserted thin ferrite disk gives an example of a nonintegrable system. The interplay of reflection and transmission at the disk interfaces together with the material gyrotropy effect gives rise to whirlpool-like electromagnetic vortices in the proximity of the ferromagnetic resonance. Based on numerical simulation, we show that a character of microwave vortices in a cavity can be analyzed by means of consideration of equivalent magnetic currents. Maxwell equations allows introduction of a magnetic current as a source of the electromagnetic field. Specifically, we found that in such nonintegrable structures, magnetic gyrotropy and geometrical factors leads to the effect of symmetry breaking resulting in effective chiral magnetic currents and topological magnetic charges. As an intriguing fact, one can observe precessing behavior of the electric-dipole polarization inside a ferrite disk.

Eigen electric moments and magnetic–dipolar vortices in quasi-2D ferrite disks

In a quasi-2D ferrite disk with a dominating role of magnetic–dipolar (non-exchange-interaction) spectra, one can observe the vortex structures. The vortices are guaranteed by the chiral edge states of magnetic–dipolar modes which result in appearance of eigen electric moments oriented normally to the disk plane. Due to the eigen-electric-moment properties, a ferrite disk placed in a microwave cavity is strongly affected by the cavity RF electric field with a clear evidence for multi-resonance oscillations. For different cavity parameters, one may observe the resonance absorption and resonance repulsion behaviors.

Manipulation of the Radiation Characteristics of a Patch Antenna by Small Ferrite Disks Inserted in Its Cavity Domain

In this paper, it is shown how the radiation characteristics of a patch antenna can be manipulated by a small number of normally magnetized ferrite disks inserted in the resonant region of the patch. It is shown that a one- and dual-band circular polarized microstrip antenna can be obtained by taking advantage of the interaction of the antenna cavity field with the magnetized ferrite disks. The scattering and radiation parameters of the antenna are investigated. The dependence of the axial ratio and the return loss of the antenna on the position and the number of ferrite disks underneath the patch are analyzed. Experimental and simulation results are in good agreement.

The field symmetry breaking effects in microwave-vortex structures originated by ferrite disks in a cavity

For a microwave resonator with an enclosed ferrite disk, one has the electromagnetic resonant fields which are not the fields of standing waves. This leads to very specific topological-phase characteristics. In such a nonintegrable system with time-reversal symmetry breaking, one obtains the Poynting-vector microwave vortices and intensive field localization in a region of a disk. The purpose of this paper is to give detailed explanations of physics of the electromagnetic-vortex phenomena shown in our recently published paper [E. O. Kamenetskii et al., Phys. Rev. E 74, 0366620 (2006)]. Based on numerical simulation, we show that for a thin ferrite disk with positive permeability parameters and negligibly small material losses, the Poynting-vector microwave vortices in a cavity are accompanied with topological magnetic currents and topological magnetic charges. Such topological sources create very unique field structures with evident symmetry breaking properties. The observed vortex phenomena open an excit...