Magnetostatic waves in a tangentially magnetized ferrite plate with a normal uniaxial anisotropy under the conditions for orientational transition

Propagation of magnetostatic waves in a tangentially magnetized ferrite plate with a normal uniaxial anisotropy under the conditions for the orientational phase transition of the second order is considered. Dispersion relations for quasi-surface and quasi-volume magnetostatic waves with the wave vector arbitrarily oriented in the plane of the plate have been obtained. The limiting frequencies of the regions of existence of both modes have been determined and the dependences of these frequencies on the anisotropy field and wave-vector orientation have been investigated.     

Propagation of magnetostatic surface waves in a ferrite plate magnetized by a spatially periodic transverse field

Propagation of magnetostatic surface waves (MSSWs) in a ferrite plate magnetized by a spatially periodic transverse field has been considered. The parameters of MSSW propagation have been calculated by the Hamilton-Auld method. It is shown that only noncollinear MSSWs, whose wave-beam trajectories as well as wave numbers and angles, which determine the directions of the vectors of the phase and group velocities, are described by functions that are periodic in the direction of the wave propagation, can exist in this field. The period of these functions is determined by the period of the spatially periodic field. The frequency range of existence of the collinear waves is narrower than that of the waves in a uniformly magnetized plate. The characteristics of wave propagation in a nonuniform spatially periodic field are compared to the characteristics of wave propagation in nonuniform fields of known types.     

Surface wave along a ferrite rod magnetized below saturation

Surface waves supported by a ferrite rod, magnetized longitudinally near and below saturation, are studied experimentally using the surface wave resonator technique. Two types of slow waves are found to exist. Their propagation constants depend on the dc magnetic field and rod size. They are interpreted as theHE_{11}mode positive and negative circularly polarized surface waves. For pure circularly polarized waves, a magnetized ferrite is considered as a dielectric with nontensor permeability. A calculation of the propagation constant of these circularly polarized surface waves, based on the dielectric analogy, is made. The agreement between calculation and measurement is close.     

The spectrum of the spin-wave excitations of the tangentially magnetized 2D hexagonal ferrite magnonic crystal

The spectrum of the spin-wave excitations (SWEs) that are localized in a unit cell of the tangentially magnetized 2D ferrite magnonic crystal is experimentally and numerically studied. The groups of SWEs that are localized in the central part of the unit cell and in the regions of the magnonic crystal parallel to its axes are identified.     

Em wave diffraction by a finite set of magnetized ferrite cylinders

The paper presents a rigorous solution of the diffraction problem by a finite set of magnetized ferrite cylinders. The main purpose of the research is to determine the steerability of scattering diagram of diffraction by several longitudinally magnetized ferrite cylinders. A plane wave scattering as well as main mode scattering by cylinders in the open end of rectangular waveguide are considered and numerical investigations are presented.     

Magnetostatic surface waves in a ferrite/dielectric/metal structure magnetized by a linearly increasing transverse field

Propagation of magnetostatic surface waves (MSSWs) in a ferrite/dielectric/metal structure magnetized by a nonuniform field whose intensity linearly increases with the coordinate normal to the direction of the magnetic field is considered. Wave trajectories are calculated. The variation of the wave number, as well as the variations of the directions of the phase- and group-velocity vectors, is investigated. Possible transformations of some waves into other modes and conditions for MSSW radiation are formulated. The parameters of ferrite/dielectric/metal structures that can be used in backward-wave devices are determined.     

Excitation of hypersonic oscillations under magnetic switching of a normally magnetized ferrite plate

Hypersonic elastic oscillations are excited in the microwave range using magnetization reversal of a normally magnetized ferrite plate due to precession of the magnetization vector around the field direction. Characteristic times are determined for magnetic and elastic oscillations, and the relation of these times with decay parameters of both processes are demonstrated. An empirical analysis using exponential functions and a model of the quasi-static rotation of the magnetization vector are employed for interpretation of the effects. Prospects for application of the effects for the excitation of high-power microwave hypersound are discussed, and a possibility of elastic oscillations with amplitudes of up to 10^?9 cm is demonstrated.     

The magnetic-wall effect on the characteristics of magnetostatic waves in an in-plane magnetized ferrite plate

The effect of the magnetic-wall boundary condition on the isofrequency and dispersion characteristics of magnetostatic waves propagating in an in-plane magnetized ferrite plate (film) is investigated. The situations are analyzed where this condition is satisfied on one of the ferrite’s surfaces and at a certain distance from it. It is found that, over the same frequency interval, such a structure supports several different types of waves simultaneously: bulk waves, surface waves, and waves whose amplitude is constant across the thickness of the ferrite film. The boundaries of the regions where bulk or surface waves propagate are determined. It is shown that a unidirectional wave propagates along the optical axis when the magnetic-wall boundary condition is satisfied on the ferrite’s surface. This means that energy is transported in the film in a single direction and cannot be transported in the opposite direction.     

The influence of a metal screen and magnetic wall on the vector line pattern of the high-frequency field of a surface spin wave

Equations for vector lines of the magnetic field and magnetic induction of a spin wave propagating perpendicularly to an external magnetic field in a dielectric–ferrite–dielectric structure tangentially magnetized to saturation and bounded on both its walls by a perfect conductor or a perfect magnetic wall are obtained. The vector line patterns of these magnetic quantities are calculated for the case when one of the dielectrics is a vacuum half-space. It is shown that the spin wave in a ferrite plate and in such structures may be considered as vortices of magnetic induction propagating in time and space. A relationship between the position of vortices of magnetic induction and the variation in the electric field of the spin wave is found. It is established that, in the structures under consideration, the vector lines do not form vortices.     

Application of Brillouin diagram for a magnetized ferrite

The construction and the applications of the Brillouin diagram for a magnetized ferrite are discussed. It is pointed out that the application of the principle of limiting absorption for the determination of the proper solution in an unbounded ferrite is readily carried out with the help of the Brillouin diagram.     

Walker mode of a ferrite column magnetized in an arbitrary direction

The Walker mode of an infinitely long ferrite column is analyzed using the magnetostatic approximation for the case of the magnetostatic field oriented arbitrarily with respect to the axis of the ferrite column. A simple expression for the only existing resonant frequency is obtained in terms of the physical parameters and the orientation of the magnetostatic field.     

Magnetostatic surface waves in a ferrite/dielectric/metal-strip-grating structure

The dispersion relation for magnetostatic surface waves in a ferrite/dielectric/metal-strip-grating structure is obtained. It is shown that dispersion of magnetostatic surface waves must be qualitatively the same as in a ferrite/dielectric/metal structure, while the slope of the dispersion curve in the region of backward magnetostatic waves existing in a ferrite/dielectric/grating structure (and in a ferrite/grating structure in particular) is considerably higher than the slope of this curve corresponding to a ferrite/dielectric/metal structure. It is found that this phenomenon can be explained by the dependence of the grating’s shielding capability on the wave number of magnetostatic surface waves. A grating shielding parameter is introduced and dependences of this parameter on the wave number that can be used to explain the phenomena observed in the experiment are determined.     

Analysis of double-layered nonradiative dielectric waveguide containing a magnetized ferrite

The propagation characteristics of the dominant mode in magnetized-ferrite-loaded double-layered nonradiative dielectric waveguide are studied. The analysis is based on mode-matching method. Numerical results are presented for various values of structure and material parameters.     

Analysis of a coupled slotline on a double-layered substratecontaining a magnetized ferrite

Nonreciprocity in the propagation characteristics of the even and odd modes in magnetized-ferrite-loaded double-layered coupled slotlines is studied. The analysis is based on Galerkin's method applied in the Fourier transform domain. Numerical results are presented for various values of structural parameters. As a result, it is found that the waveguide structures studied have sufficient nonreciprocity in propagation constants for isolators and four port circulators     

高频地波雷达中电离层杂波的时频特征

高频地波雷达中的电离层杂波通常可分为聚集区和扩展区,聚集区杂波对应于经电离层直接反射的回波,距离扩展较小,表现为单(或多)分量调幅-调频(AM-FM)信号;扩展区对应于复杂混合路径的回波,具有较大的距离域和时频域扩展.电离层聚集区杂波在距离上的相关性明显高于正常海洋回波,而扩展区杂波的距离相关性则相对较弱.利用雷达杂波的时频特征,可以对电离层聚集区回波进行时频面掩模处理抑制强杂波,或利用相邻距离元上的回波信号进行杂波对消.雷达实测数据处理结果表明上述分析和杂渡抑制方法是有效的.     

Wave diffraction by a finite set of azimuthally magnetized ferrite cylinders

The article is devoted to the problem of scattering of plane linear and circular electromagnetic waves by a set of ferrite-coated cylinders. Particular attention is paid to the possibility of controlling the scattering pattern by the azimuthal magnetic field induced in the ferrite by the dc current in metal core of cylinders. It is shown that the best sensitivity can be obtained for the magnetic field, which provides the magnetic resonance inside ferrite layer. Relevant scattering patterns are also presented.     

Interaction between the electron beam and the surface wave in a dielectric plate

A model of the traveling-wave tube (TWT) that includes a dielectric plate adjoining a perfectly conducting surface and a metal screen parallel to the plate is considered. The dispersion equation in the presence of a homogeneous electron beam filling the space between the plate and the screen is derived. The method of differentiation of the dispersion equation is used to obtain and calculate coefficients of the TWT characteristic equation and coupling and depression coefficients, i.e., coefficients determining the main properties of the TWT. The considered model is compared with an “impedance” comb structure and a cylindrical helix. Conclusions concerning the prospects of development of a “dielectric” TWT are drawn.     

The near fields formed by a negative-metamaterial plate

A metamaterial layer with parameters ɛ and μ close to minus unity (a Veselago lens) is considered. The 2D problem of excitation of this layer by a point source is studied. Under the assumption that the thickness of the layer is much smaller than the wavelength, explicit analytic expressions for the field are obtained. Field patterns in various sections of the structure are presented.     

Electric and magnetic fields of a wave in proximity of aprogressively phased periodic structure

Unexpected waves have been observed that were localized in the region of, and propagating along, a progressively phased periodic structure. These waves are related to a dominant TM₀ mode associated with and bound to a thin dielectric layer covering a conducting plane