1. Absorption of electromagnetic energy of dipole antenna of double layer dielectric sphere
wave absorption, double layer dielectric sphere, Perfectly conducting spherical screen, radial dielectric dipole, dual series equations, method of analytical regularization
Vestnik KhNU ¹712 Pages. 62-66
Considered the problem of electromagnetic energy absorption by double layer sphere, which the simplified model of human head protected by the helmet with the dipole antenna. This investigation is interesting due to control of energy absorption in sensible parts of human head tissues. The problem is solved by method analytical regularization, which reduces the problem to the system of linear equations of Fredholm second kind which provides guaranteed convergence. Basic absorption characteristics are obtained and comparison of protection effectiveness for different sizes helmets are made
2. Features of forming patterns of planar antennas arrays
A.A. Bulgakova, N.N. Gorobets, V.A. Katrich, V.A. Lyashenko
Planar arrays, Pattern, sidelobes, radiator elements, interference maximums triangular grid
Vestnik KhNU ¹712 Pages. 71-75
Computer analysis results of an influence of a radiating aperture form of the planar array on its pattern have been presented. It is shown that there is dependence of levels of interference lobes and also near and far sidelobes of pattern in one of main positions of observation planes on number and radiators in plane which is orthogonal to main observation plane
3. Modelling of holographic radar with discrete and continuous aperture
B. Kochetov, A. Butrym
holographic radar, method of maximum likelihood, Point scatter
Vestnik KhNU ¹712 Pages. 76-79
Images of a point scatter are investigated that are obtained with a model of holographic radar with discrete and continuous aperture, under illumination with planar or spherical wave. Main features of the scatter image are revealed and their dependence on parameters of the radar (aperture dimensions, elements spacing in the gratings, type of illumination) are studied
4. On the field fluctuations in the diffraction pattern of focusing systems
fluctuations, amplitude, Phase, focal plane
Vestnik KhNU ¹756 Pages. 5-10
There are considered the amplitude and phase fluctuations of the field in the focal plane of the focusing system, when a was with the field fluctuations falls on it. Plots illustrating the distribution of dispersions of amplitude and phase of the field along coordinate axes in the focal plane are given. There are analyzed a general case when both the amplitude and phase fluctuation of the field are present in the incident wave, as well as cases when it is possible to be restricted by regard of only either the phase or the amplitude fluctuations of the field in the antenna aperture. It is shown that in the latter cases, for determination of dispersions of the phase and amplitude fluctuation of die field in the focal plane, it is possible to use the same pictures with tk corresponding replacement of curves and conclusions accompanying them.
5. Radioacoustic wind sounding of the atmosphere bo un dat y layer: history of the development and perspectives
Y. N. Ulyanov, V. I. Vetrov, N. G. Maksimova
radioacoustic, wind, sounding, atmosphere, boundary layer, Profile, adaptation
Vestnik KhNU ¹756 Pages. 27-32
The article is devoted to the potentialities of the method of radioacoustic sounding when monitoring the vertical structure of the wind in the atmosphere boundary layer (ABL). A review of methods for radioacoustic measurements of the horizontal wind velocity and direction is based on the developments of the authors and their experience in this field as well as on the world experience. It is emphasized that the radioacoustic method for sounding the wind in ABL is perspective, since for the RAS equipment, there are not characteristic neither high levels of the electromagnetic pollution of the environment like for radiolocation wind profilers - radars nor loss of the serviceability at ligh levels of the ambient acoustic noise like for acoustic wind profilers - sodars.
6. ELECTRODYNAMIC MODELING OF COMPOSITE MEDIA WITH SIMALTENEOUSLY NEGATIVE REAL PARTS OF PERMITTIVITY AND PERMEABILITY
S.N. Shulga, I.E. Khodasevych
composite media, thin-wire resonance inclusions, Permittivity, Permeability, scattering of electromagnetic waves
Vestnik KhNU ¹756 Pages. 38-41
This paper presents physical and mathematical model and investigation of electromagnetic properties of composite material made of straight and curved conducting resonance inclusions placed into isotropic media and forming periodic lattice. The effective constitutive parameters of the composite material are found. It is revealed that on resonance frequency real parts of permittivity and permeability of such media can assume simultaneously negative values. The problem of reflection and transmission of plane electromagnetic wave through a sequence of layers made of such composite material is solved, numerical results are presented
7. The analytical method for a periodical sequence of the alternate grates of dielectric bars investigate
thick grate of dielectric bars, anisotropic layer, Periodic structure, Propagation constant, scattering coefficients
Vestnik KhNU ¹756 Pages. 79-82
The electromagnetic properties of a finite periodic sequence of the thick grates of dielectric bars are investigated. The grates are identified with the homogeneous anisotropic layer of an appropriate thickness, in order to generalize, the layers which anisotropic properties of both permittivity and permeability are employed. The sequence scattering .coefficients are determined in analytical form using the circuit theory and the matrix functions techniques. Physical analysis of the frequency, angle and interference dependencies of the scattered field amplitude is carried out.
8. The Gaussian beam scattering on the bounded sequence of alternate grates of dielectric bars
V.B. Kazanskiy, V.R. Tuz, D.V. Yudintsev
Gaussian beam, thick grate of dielectric bars, anisotropic layer, Periodic structure
Vestnik KhNU ¹756 Pages. 83-86
The Gaussian beam scattering on bounded periodical sequence of thick grates of dielectric bars are investigated. Identification of discrete structure with appropriate thickness homogeneous anisotropic layer was carried out for define sequence basic element transmission matrix. The sequence scattering coefficients were written down via Mougin polynomials. The effects of form distortion, beam splitting into several beams, side shift of beam axe were shown. Their correlation with scattering coefficients phase and module angle dependence of separate grates was established.
9. Amplitude and noise features of detectors a mm of range of lengths of waves on base of contacts a metal-semimetal BiSb
O.N. Sukhoruchko, V.T. Plaksiy, E.D. Prokhorov, A.V. Dyadchenko
contact metal-semimetal BiSb, Power zones, contact a metai-semimetal BiSb, millimeter range of lengths of waves, relative noise temperature, influence of displacing and resistances of contacts on sensitivity
Vestnik KhNU ¹756 Pages. 113-117
In work are brought results of analytical and experimental thermoelectrical detector study with the point contact a metal-semi-metal BiSb. Determined relative noise temperature, as well as influence of displacing and resistances of contacts on the sensitivity in 8 mm range of waves.
10. Directed and polarization characteristics of the aperture of the circular waveguide with impedance flange
N.N. Gorobets, V.M. Dakhov, I.V. Gorbach
microwave, antennas, waveguides, Polarization, Pattern
Vestnik KhNU ¹806 Pages. 3-7
The amplitude and polarization patterns of the radiator in the form of the aperture of circular waveguide with impedance flange, excited by the dominant wave, have been measured by the method of the indicator antenna with polarization plane rotation. It is shown that such radiators have an axial-symmetric pattern, a wide polarization pattern and a low level of side lobes.
11. RECTANGULAR WAVEGUIDE M.V.
millimeter range, Parametric amplifier, oscillatory system, band of the reinforcement, relative noise temperature
Vestnik KhNU ¹806 Pages. 18-21
Semiconductor two-stage parametric amplifiers have been developed to be used in the input circuits of communication and navigation systems in the short-part of millimeter wave band. In the 60 to 65 GHz range, the gain is no worse than 15 dB at -3 dB level in 1 to 1.6 GHz bandpass. The noise temperature is no higher than 500K when the quasi-optical IMPATT oscillator is in using as the pumping generator.
12. Way of transformation of the patterns of reception antennas
A.A. Sorokin, A.F Sorokin, O.V. Sokolova, R.N. Zaluzhniy, N.N. Gorobets
miñrowaves, antennas, Pattern, Frenel zones
Vestnik KhNU ¹806 Pages. 29-32
the expedient of management by the shape of directional diagrams with the help of a fragmentation of Frenel zones is offered. Measuring the shape of a pattern diagram of the horn and spiral antennas are carried out. Peak allocations a builder of a field in short-range, medial and long-range bands for different frequency range are received and analyzed. By results of experiments intensity, a corner, radius for long-range and short-range bands is constructed 3D images.
13. Thermo equilibrium and differential capacity of p+-n junction
P+- n junction, distribution of potential
Vestnik KhNU ¹806 Pages. 48-53
The accurate distribution of field and potential in the region of abrupt p+- n junction under thermodynamic equilibrium is obtaned. The formula of p+- n junction width with any relation of mobile charge carrier magnitude and ion donors of n-region is obtained. The dependence of p+- n junction differential capacity upon out voltage, which does not need numerary methods is obtained. It was shown, that under direct and reverse switching of p+- n junction the dependence of capacity upon voltage is more complicated than for p- n junction in the depletion mode.
14. Thermo equilibrium state of p+-p junction
P+-p junction, distribution of potential
Vestnik KhNU ¹806 Pages. 54-58
The thermo equilibrium state of p+-p junction with surface charge of p+-region was investigated. The distribution of field and potential in the region of such junction is describing by Poisson's equation with un-known charge distribution on coordinate. The solution method of this equation allowing to obtain precise distribution of field and potential on coordinate was proposed. The formula for width of p+-p junction with any ratio of mobile charge carriers and charge of ion-acceptors in p-region was obtained.
15. Identification and localization of radar impulses buried in noise
A. G. Tyzhnenko, Y. V. Ryeznik
radar, Pulse, identification, localization, low SNR
Vestnik KhNU ¹806 Pages. 70-74
Statistical method identification and localization of radar impulses buried in noise is addressed. To this end, the correlation coefficient between carrier samples measured in the extremal points and analogous set of points of received signal is proposed to implement. Such measurements for receiving signal need to be done at least by one tenth of the half period of the carrier. Because of very simple algorithm proposed, such measurements do not lead to heavy computational burden. To decrease identification and localization errors for given signal to noise ratio (SNR) one needs to increase the number of measurements points, and hence, the pulse width. To prevent this issue, one can increase the carrier frequency. In general, the method accuracy increases with the carrier frequency. The method proposed permits theoretically to identify with fidelity impulses buried in noise for SNR lower than -30 dB.
16. Spatial and temporal features of the midlatitude total electron content
I. G. Zakharov
total electron content, dual-frequency Doppler shift measurements, Planetary waves
Vestnik KhNU ¹806 Pages. 82-86
Experimental study of the latitudinal and diurnal variations in the total electron content over Eastern Europe are present. The dual-frequency Doppler shift measurements from navigation satellites and incoherent scatter radar (ISR) data are used The ISR data were collected near Kharkiv city (49.6oN, 36.6oE), and the dual-frequency signals from navigation satellites in circular polar orbits at the altitude of about 1000 km were received at the Kharkiv V. Karazin National University Radiophysical Observatory (49.6oN, 36.3oE). The calculated total electron content maps span the 35o – 65oN geographic latitude range and the 24-hour local time range. These maps and other data represent all known features of diurnal and latitudinal total electron content variations at middle and subauroral latitudes, and in particular, they represent the local latitudinal maximum at 50oN geographic latitude in total electron content. The results obtained also indicate that tidal and planetary-scale waves act to noticeably modify the temporal and spatial variability of TEC, including that under quiet conditions.
17. QUEST AND CREATION OF NOVEL ACTIVE MEDIA FOR DYE LASERS IN IRE NAS OF UKRAINE
laser dye, molecular structure, spectrum, fluorescence, quantum yield, lasing efficiency, Photostability
Vestnik KhNU ¹806 Pages. 92-98
Numerous studies of novel active media for dye lasers fulfilled in IRE NAS of Ukraine are generalized in present review. Peculiarities of spectral, fluorescence and lasing characteristics of some laser dye classes for visible region of the spectrum have been analysed. A special attention is focused upon effects of structure of the dye molecule and its solvent environment on these characteristics. The outlook of development for dye-doped active media has been discussed
18. Earth profile plotting using pulse radar with scanning antenna array
A. S. Kutsenko, Î. V. Kazansky, N. N. Kolchigin
Pulse radar, antenna array, radar image
Vestnik KhNU ¹834 Pages. 37-41
This paper is devoted to development of radar signal processing technique which allows one to reconstruct earth profile and reveal and identify manmadc objects which arc situated on underlaying surface. The technique of signal processing and image construction is based on measuring of directional characteristics of the scene being investigated. Modeling of radar activity has been performed; radar images of some simple scatterers have been obtained. Possibility of using the technique for scene profile reconstruction and revealing of manmade objects situated on it has been shown
19. Far-field distance of waveguide radiators
N.N. Gorobets, E.E. Ovsyannikova, A.V. Shishkova
rectangular waveguide, microwaves, boundary of far zone, amplitude, Phase radiation characteristics
Vestnik KhNU ¹834 Pages. 68-76
On the basis of Hertz potentials in Kirchhoff approximation the amplitude and phase radiation characteristics of open-ended rectangular waveguide excited by TE10 dominant mode are investigated at arbitrary distance from radiating aperture. The estimation criteria of far zone boundary for small (in comparison with the wavelength) waveguide radiators are presented. For such small radiators, the classic formula for calculation of far-field distance cannot be applied. Under suggested criteria the investigation of radiation characteristics are carried out. For waveguides with the sizes less then the wavelength in the waveguide, the boundaries of far-field distance are defined
20. Electromagnetic waves focusing inside dielectric cylinder
N. N. Gorobets, N. N. Stasjuk
microwaves, dielectric cylinder, Plane wave, focusing points
Vestnik KhNU ¹834 Pages. 77-84
Computation and analysis of electrical and magnetic field amplitudes at focusing points inside dissipative dielectric cylinder illuminated by plane linear polarized wave have been performed using the approximation of geometric optics. It was shown that in the focal region fields vary according to oscillating law and field longitudinal gradients the more cylinder diameter and dielectric permittivity, the large at that. Results of investigation allow to explain subthreshold (nonthermal) exposure of millimeter and submillimeter electromagnetic waves on human and other biological objects
21. Global Sensitivity analysis of the dipole matrix element according to variation of parameters of the indium surface segregation in ingan/gan quantum well
indium surface segregation, semiconductor nitrides, Piezoelectric polarization, dipole matrix element, global sensitivity analysis
Vestnik KhNU ¹853 Pages. 8-14
In this paper, influence of the indium surface segregation on dipole matrix element for InGaN/GaN heterostructure is under investigation. The global sensitivity analysis has been applied for quantitative estimation of the indium surface segregation effect at each interface of the quantum well. Together with the indium surface segregation, the piezoelectric effects are considered. It has been shown that joint action of the piezoelectric fields and the indium surface segregation leads to changes in the selection rules for optical transitions. Results give the method to apply the optical spectroscopy for observation of the indium surface segregation
22. Influence of aperture-illumination law on near-field characteristics of aperture antennas
E.E. Ovsyannikova, A.V. Shishkova, N.N. Gorobets
electromagnetic waves, reactive fields, aperture radiators, Kirchhoff technique, near-field, far-field, amplitude distributions, Phase characteristics, amplitude characteristics, reactive radiation power
Vestnik KhNU ¹853 Pages. 28-36
On the basis of Hertz potentials the investigation of near-field reactive region of square aperture antennas with various aperture illumination laws has been carried out. The influence of the field amplitude distribution law in the aperture on the extension of this region has been studied. The calculation and analysis of amplitude, phase and power radiation characteristics, including reactive radiation power density, at the different planes in near-field region have been carried out. The analysis of the criteria for estimation of near-field reactive region boundary has been carried out
23. Algorithm of a pulse signals delay definition, based on a Hilbert's transformation
D.O. Batrakov, D.V.Golovin, S.V. Grekov, A.G. Batrakova*
Pulse signals, definition of a delay of signals, Hilbert's transformation, Plane-layered media, thickness measurements
Vestnik KhNU ¹853 Pages. 71-76
In the present paper the algorithm of processing of the pulse signals reflected from plane-layered media is offered. It is supposed, that an effective thickness of layers less than spatial size of an impulse. This feature of a problem complicates use earlier proposed methods of signals time delay evaluating. Therefore in paper the theoretical analysis of possibilities of various approaches for processing of signals is carried out and the algorithm and the corresponding software for definition not only a time delay, but also physical and geometrical characteristics of investigated objects are offered. Results of numerical modelling and experimental researches for the purpose of definition of sensitivity and resolution of a method, and also possibility of its practical use are given
24. Theoretical investigation of photonic crystals by means of analysis of photonic density of states maps
Photonic crystal, Photonic density of states, transmittance spectrum, Plane wave expansion method, finite differences method
Vestnik KhNU ¹853 Pages. 77-83
In the work, there have been computed the photonic density of states maps of the 2D photonic crystal by means of plane waves expansion method by the analogy with photonic band gap maps. The photonic density of states maps allows precise determination of the parameters of photonic crystals during the design process of the photonic crystal-based device. Moreover, there have been carried out the comparison with analogous characteristics obtained by the finite differences time domain method. Comparison results indicate the similarity of results obtained by two methods, however, the computation of photonic density of states maps requires much less time at the same computation precision. Moreover, in the work there have been carried out the comparison between the efficiencies of the photonic density of sates maps and the photonic band gap maps analysis methods
25. Dielectric permittivity profile reconstruction by frequency probing problem for a plane-layered media with regard to dispersion
Batrakov D.O., Simachov O.A.
Plane layered media, dispersion, inverse problem, dielectric permittivity
Vestnik KhNU ¹883 Pages. 45-49
In the present paper the problem of dielectric permittivity profile reconstruction with regard to dispersion is discussed. The nature of dispersion function is assumed to be known and unknown functions are real and imaginary parts of dielectric permittivi
26. Microstrip structures with photonic band gap
Fesenko V.I., Sukhoivanov I.A., Shul'ga S.N.
Photonics band gap, microstrip, filter
Vestnik KhNU ¹883 Pages. 20-24
In this paper, it is presented a two-sided one-dimensional photonic bandgap microstrip structure. The structure is obtained by etching a one periodic pattern of circles in the ground plane of a microstrip line and variation of the characteristic impedance
27. Determena Frequency properties of intervalley electron transfer in AlN
V. T. Plaksiy, À.V.Arhipov, À. S. Tischenko, Ò. ². Kamishanova, E.D. Prokhorov, À.V.Dyadchenko, D. P.Chueshkov
Perfect crystal, zone overcrystallization, temperature gradient
Vestnik KhNU ¹966 Pages. 19-22
The problem of growing of perfect bismuth-antimony monocrystals having of a uniform distribution of Sb atoms through the crystal by help floating-zone refining method is considered. The expression for temperature gradient in melt and temperature distribution for any melt point have been obtained.
The monocrystals growing maximal velocity have been estimated. The growing velocity must be lower then 1 mm per hour was showed. It is velocity not lead to concentration overcooling and arising inhomogeneous dendrite structure. For solution with certain composition ( at = const) overcooling may be eliminated by either increasing of temperature gradient in liquid faze or decreasing growing velocity are showed.
28. Signal scattering on the meteor trail
signal scattering, meteor trail, diffraction oscillations, electron density, Plasma collective interaction, impulse response.
Vestnik KhNU ¹966 Pages. 90-96
A generalized model of the radiosignal scattering on the meteor trail is proposed. The model allows to take into account the process of formation and development of the meteor trail, and to calculate the scattered signal power change without sharing the meteor trails on underdense and overdense. As input parameters of the model used the physical parameters of the meteoroid - the mass and velocity, which determine the ionization of the plasma formation, as well as the location and orientation of the meteor trail. In the derivation of the analytical relations taken into account the presence of the plasma sheath surrounding the 'metal cylinder' and the collective interactions in the plasma. In the paper shown that the results of calculations are in good agreement with observations.
Photonics band gap, microstrip, filter
Vestnik KhNU ¹883 Pages. 20-24
In this paper, it is presented a two-sided one-dimensional photonic bandgap microstrip structure. The structure is obtained by etching a one periodic pattern of circles in the ground plane of a microstrip line and variation of the characteristic impedance as a function of the length of the microstrip line. The calculated scattering parameters of the proposed filter are presented.
diffraction electromagnetic waves, chiral structure, Polarization properties on frequency
Vestnik KhNU ¹883 Pages. 54-58
In given paper the diffraction of electromagnetic waves on volume grid is investigated experimentally. The grid consists of rectangular elements. Two planes of two-dimensional periodic rectangular metallic string elements located on both dielectric surfaces and connected by cylindrical conductors. The measurements of dependence of grid transmission index on frequency and polarization are carried out. The measurements were made in frequency range 26-38,8 GHz. The grid was irradiated by quasi-plane wave with incident on the normal to the surface of the grid.
31. The xecl laser with the adjustable shape and duration of generation pulse
S.S. Anufrik, A.P. Volodenkov, K.F. Znosko
LC- contour, XeCl laser, excitation system, generation energy, Pulse duration.
Vestnik KhNU ¹983 Pages. 3-10
The generation parameters of LC-contour excitation system are studied for electro-discharge excimer XeCl laser using a Ne–Xe–HCl mixture. A computation model is developed for finding the generation parameters. It has allowed us to calculate current, voltage and generation power oscillograms for all parameters of the electrical excitation system. The program of XeCl-laser modeling enables to calculate an electrons, atom and molecule concentrations, specific energy deposition in active medium also. By means of program Bolsig + calculation of rate coefficients of reactions with participation of electrons is executed. It is shown that generation of short radiation pulses (20 ns) and relatively long pulses (60 ns) is possible due to changing of LC- contour parameters. Energy of generation reaches a maximum at use of small values of peaking capacity, which are significantly smaller then value of storage capacity.
laser radiation, acoustic emission, Plasma, crater, a zone of non-elastic destruction, laser-plasma evolution.
Vestnik KhNU ¹983 Pages. 11-17
Acoustic emission of a zone of the destruction formed during influence of pulse laser radiation on a surface of metal is considered. Dependence of the time form of acoustic fluctuations on parameters of an irradiated material and the law of increase in depth of a crater was estimated. It is revealed, that at action on a surface of the copper sample of a laser impulse duration 20 ms time of growth of a zone of destruction makes approximately 40 ?ñ, that will well be coordinated with time of existence of plasma formation at a surface of the target exposed to laser-plasma processing (50 ms).
waveguide resonator, misalignment of the mirrors, terahertz range, energy losses, mode composition, Polarization
Vestnik KhNU ¹983 Pages. 18-22
The influence of the curvature of the spherical mirror for metallic waveguide resonator of submillimeter laser (lambda = 0.4326 mm) on energy losses and the mode composition of radiation is investigated. It is shown that the presence of quadratic phase aberrations in the mirrors of the waveguide cavity with an increase of its Fresnel number at monotonically decreasing of the energy losses for fundamental asymmetric mode TE11q due to a decrease of waveguide losses also leads to their substantial non-periodic oscillation.
nonlinear dielectric, Polariton spectrum.
Vestnik KhNU ¹983 Pages. 23-28
The properties of polaritons in nonlinear dielectric medium are considered. The spectrum of polaritons is got, the dependence on intensity of electromagnetic field of number of branches and width of gaps in the spectrum is investigated. New branches arising up in the gap of polariton spectrum are found. The ratio of electromagnetic and mechanical energy of a polariton wave propagating in nonlinear dielectric is considered. It is shown, that if the frequency of polaritons go up towards the lower limit of spectral gap, the fraction of electromagnetic field energy at polariton wave goes down and tends to zero, but for the polaritons with frequency higher than upper limit of gap, the fraction of the electromagnetic field energy tends to 100 % with increasing of frequency.
35. Light propagation characteristics of optical metal dielectric coaxial nano-waveguides with complex shapes
O.N. Kozina, I.S. Nefedov, L.A. Melnikov
Plasmonic waveguides, coaxial, noble metals, numerical simulations, nano-size.
Vestnik KhNU ¹983 Pages. 48-53
The properties of new optical waveguides with nanosize cross-section made of noble metals and glasses are described. This waveguide supports propagation of modes with unusual propagation properties. For estimation of the field localization, losses, propagation length, velocity and others characteristics the numerical simulations by FEM method has been used. Coaxial waveguide with the annular and the elliptic central rods are considered. The comparatively low value of losses has explained.
grid, bolometer, intensity distribution, Polarization, energy center, beam diameter, generalized cross-sectional square of the beam.
Vestnik KhNU ¹983 Pages. 72-76
In this paper the grid receiver for measuring laser radiation characteristics has been considered. The receiver contains four grids located perpendicular to the direction of propagation. Wire elements are located at angles 0 , 45?, 90? and 135? to the vertical. One grid contains 8 nickel bolometers with diameter 40 microns, bolometers are located on 7.2 mm from each other. The diameter of the window – 60 mm. Intensity distribution in the space has been measured, therefore, the position of the energy center, the diameter, the generalized cross-sectional square of the radiation beam have been determined. The Radon transformation has been used as the mathematical basis of signal processing algorithms. Also the polarization direction and intensity distribution of polarized radiation have been measured by a numerical experiment.
Plasma, surface plasmons (plasmon resonances), scattering cross section, eigenvalues.
Vestnik KhNU ¹983 Pages. 84-90
Plasmon resonances of an isolated plasma cylinder and if a pair of coupled plasma cylinders are theoretically investigated. Mechanism of the plasmonic modes coupling that can be considered as symmetric and antisymmetric combinations of isolated cylinders plasmons is investigated. Accurate analysis of the spectrum of different Plasmon resonances is presented. Significant enhancement of the field in the case of distant cylinders in comparison to isolated one is revealed (separation distance is near 10-20 radii). The calculation accuracy is estimated. Figures show the scattering cross section of plane wave on the isolated plasma cylinder and on the pair of coupled cylinders and the real part of the eigenfrequency of the plasmon modes. Near field spatial characteristics of plasmons are presented.
holography, Physiological optics, retina, uniaxial crystal, form-birefringence, Fresnel's formulas.
Vestnik KhNU ¹983 Pages. 91-101
Theoretical analysis of the laser radiation transmission at interface between the quasi-crystalline layers of the retina (a layer of nerve fibers and photoreceptor disks) is analyzed in a frame of holographic model of physiological optics. To solve the problem, we have obtained analogues of Fresnel's formulas for the interface between two uniaxial crystals. The results may be applied for diagnosis and treatment of ophthalmologic diseases by laser techniques.
Plane dielectric waveguide, inverted dielectric waveguide, Fourier transformation, Fredholm integral equation, dispersion equation.
Vestnik KhNU ¹927 Pages. 78-84
The eigenvawes problem of inverted dielectric waveguide is considered. The cross-section of waveguide is divided into partial domains in such way that the field in each domain is represented as a superposition of eigenwaves of a plane dielectric waveguide. Using the equality conditions of tangential components of electric and magnetic fields at the interface of domains two Fredholm integral equations of the second kind relatively waves amplitudes are obtained. The symmetric and asymmetric waves are considered. The dependencies of the propagation constant versus wave number and field distribution in the waveguide are presented.
wavelet-analysis, continuous wavelet transform, dynamic energogram, space radio physics, Powerful non-stationary disturbance sources.
Vestnik KhNU ¹927 Pages. 96-102
Development and improvement of methods of time-frequency analysis of signals with continuous wavelet transform usage were proposed. The new method consists in the simultaneous analysis of wavelet spectrum and dynamic energograms of the continuous wavelet transform. Using the example of analysis of real non-stationary, non-linear and ultra wideband signals and processes in space radio physics problems, in particular, using the analysis of effects, caused by the powerful, non-stationary action, the dynamic energogram method effectiveness was shown.
Polarization converter, Bragg reflector, anisotropy
Vestnik KhNU ¹927 Pages. 43-47
Today, there are two fundamental type polarization converters, passive and active, are widely used in optical circuits. In this paper, we present a passive polarization converter for near infrared range. The converter reported here is porous silicon-based structure consists of N distributed Bragg reflectors (DBR) separated by N-1 defects. The method of the electromagnetic field’s scalarization and finite difference technique were used for calculation of spectral characteristics. The transmittance spectra of the proposed polarization converters for the both polarization of the incident plane wave are presented
founded: 41 result (s)