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1.  Integral representation of green function in parallel-plate and rectangular waveguide, and in resonator as well
V.A. Katrich, F.S. Novokhatsky
waveguides, Green function, Fundamental solution, radial function, elliptical teta- function, image method, calculus of residues, integral transformation, grating, Formal variative
Vestnik KhNU 712 Pages. 67-70

The known results connected with Green function representation by elliptical theta-function are generalized. New representations of Green function for some widely used types of waveguides are obtained. Earlier, these Green functions are presented either in form of series with nonuniform convergence or in form of integrals containing Hancel functions, which are reduced to asymptotic expressions in far zone. On this work integral representations of Green functions are obtained for Cases where the quadrature formula exists. The method of analytical continuation with parameter is applied



2.  The finite difference scheme in time domain (FDTD) and analytical solution to Klein-Gordon equation
Yu Zheng, B. A. Kochetov, A.Yu Butrym
Klein-Gordon equation, FDTD, Finite difference equation, Laguerre impulse
Vestnik KhNU 712 Pages. 91-94

A finite difference algorithm for solving inhomogeneous Kleine-Gordon equation in Time Domain with arbitrary waveform pointwise source is considered in the paper. The numerical results were compared with analytical so-lution that was obtained using Laplace transformation in a convolution operator form. The results confirm validity of both the obtained numerical algorithm and the analytical solution



3.  Impedance of connected in series diodes with difference negative conductivity
E.D. Prokhorov
tunnel diode, negative conductivity, Frequency range
Vestnik KhNU 712 Pages. 111-114

The impedance connected in series negative difference conductivity diodes in wide frequency range are analyses. There are frequency region that diodes combination work have been appeared. The operation frequencies for combination of tunnel diodes are 35-40 GHz



4.  On the field fluctuations in the diffraction pattern of focusing systems
Ya.S. Shifrin
Fluctuations, amplitude, phase, Focal plane
Vestnik KhNU 756 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.  THE INFLUENCE OF MUTUAL COUPLING ON RADIATION CHARACTERISTICS OF ANTENNA ARRAY FOR VIDEOPULSE EXCITATION
O.V. Kazansky
mutual coupling, Finite TSA arrays, Van-Atta array, videopulse
Vestnik KhNU 756 Pages. 57-60

In paper antenna array from finite number of the elements, which are exited by a videopulse is observed. The model for calculation of radiated fields of antenna taking consideration of mutual coupling between elements is proposed. A directed characteristics analysis of the retrodirected systems, Van-Atta array, from finite number of elements and wave form of radiated and reradiated signals are investigated in case of excitation by a videopulse. Recommendations to decrease mutual coupling is proposed. The case of useful influence on characteristics of a radiated pulse signal is considered



6.  GAUSSIAN EXPANSIONS FOR RADIATION PATTERN OF AN OPEN-ENDED LINE WITH IMPEDANCE BORDERS
A.P. Udovenko
aperture distribution, impedance border, orthogonal functions, diffraction integral, Feed
Vestnik KhNU 756 Pages. 87-90

Near-field and far-field two-parameter expansions in terms of Laguerre-Gaussian orthogonal basis functions are proposed, which take into account the effect of impedance feed borders. The expansions enable the feed characteristics on a base of lines with impedance borders to be calculated in wide frequency region. Radiation intensity distributions for the open-ended two-layer metal-shielded dielectric waveguide in a nonresonance regions of surface impedance varying, relative errors of expansion truncations, comparison with experimental data are presented



7.  SELECTIVE excitation of the HIGH-order MODES IN THE waveguide quasioptical RESONATOR
A.V. Volodenko, O.V. Gurin, A.V. Degtyarev, V.A. Maslov, V.A. Svich, A.N. Topkov
waveguide quasioptical resonator, excitation of the high-order transverse modes, an amplitude filter, Fourier optics
Vestnik KhNU 756 Pages. 123-131

The method of the space Fourier-filtration for selective excitation of separated high-order transverse modes in the waveguide quasioptical resonator with a high discrimination degree of undesirable modes is proposed and realized. It is carried out numerical study of characteristics of some the lowest on loss transverse modes of the dielectric and metal resonators of the submillimeter laser from geometric sizes of reflectors and parameters of the space filter on the nonuniform mirror. Configurations of the amplitude-stepped mirrors for shaping the high-order transverse modes in the laser resonators containing waveguides and open parts are proposed



8.  Way of transformation of the patterns of reception antennas
A.A. Sorokin, A.F Sorokin, O.V. Sokolova, R.N. Zaluzhniy, N.N. Gorobets
mirowaves, antennas, pattern, Frenel zones
Vestnik KhNU 806 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.


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9.  The influence of a dispersion and losses to the interaction of impulse signal with the model of the biological tissues
O.N. Zheryobkina, O.V. Kazanskiy
impulse signal, a biological tissue, time domain, Flatlayer dielectric, dispersion
Vestnik KhNU 806 Pages. 40-43

In this paper the interaction of the impulse signal with biological tissues on an example of the flatlayer dielectric that models consecutive layers a skin, fat, muscle tissue is investigated. In this model, it is taken into account dispersion of the dielectric permeability and losses in a medium. The calculation program is received in result. It accounts the space-time characteristics of the reflected and past signals for layers of the flatlayer dielectric with parameters of biological tissues. Influence of values of the dielectric permeability and angle of incidence on the characteristics of past and scattered signals also is considered.


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10.  Selection of the high-order modes in the waveguide resonator by means a phase-shifting mirror
A.V. Volodenko, O.V. Gurin, A.V. Degtyarev, V.A. Maslov, V.A. Svich, A.N. Topkov
waveguide quasioptical resonator, excitation of the high-order transverse modes, a phase filter, Fourier optics, selection
Vestnik KhNU 806 Pages. 87-91

The method of the space Fourier-filtration for selective excitation of separated high-order modes in the metal waveguide quasioptical resonator with a high discrimination degree of undesirable modes is realized. It is carried out numerical study of characteristics of some the lowest on loss transverse modes for the metal resonators of the submillimeter laser from resonator geometric sizes and parameters of the phase filter on the nonuniform mirror. Configurations of the phase-shifting mirrors for shaping of the high-order transverse modes in the laser resonators containing waveguides and open parts are proposed


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11.  QUEST AND CREATION OF NOVEL ACTIVE MEDIA FOR DYE LASERS IN IRE NAS OF UKRAINE
V.V. Maslov
laser dye, molecular structure, spectrum, Fluorescence, quantum yield, lasing efficiency, photostability
Vestnik KhNU 806 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


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12.  Increase of free volume 0f the aip abundant in the water by the millimeter waves of low intensity
B. G. Yemets
electromagnetic waves, air bubbles, Field of temperature, convection
Vestnik KhNU 806 Pages. 103-106

Using an NMR technique the volume growth of the free ("bubble") air contained in water caused by low-intense electromagnetic waves is obtained. This change is caused by rectified diffusion of the dissolved air mass into bubbles. The increase in the free air may occure only under those conditions when there is no convection in the liquid, i. e. in the case of irradiating by means of low-intense waves.


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13.  Features of the calculation of Fock-type integrals
V.I. Vyunnik, A.A, Zvyagintsev
Fock-type integrals, numerical integration, error estimate
Vestnik KhNU 834 Pages. 52-62

Calculation of Fock-type integrals, used at the solutions of the diffraction problems on convex bodies is considered. The method of calculation of this integrals is described, and the estimation of their convergence is given. Range of values of the complex parameter, describing a surface impedance, for which the given method is applicable is determined. The estimation of the error of calculation is carried out


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14.  Electromagnetic waves focusing inside dielectric cylinder
N. N. Gorobets, N. N. Stasjuk
microwaves, dielectric cylinder, plane wave, Focusing points
Vestnik KhNU 834 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


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15.  Potential of a spherical segment which is placed within a spherical layer with circular aperture.
V.A. Rezunenko
electrostatics, spherical segment, layer, Fredholm integral equation
Vestnik KhNU 834 Pages. 120-126

The rigorous solution of an axially symmetrical electrostatics problem is obtained. The potential of an ideal spherical segment, which is placed within a spherical layer with circular aperture, is analyzed. We use the methods of regularization, separation and inversion of summarized equations, the method of residues in singular points of analytical functions, the methods of contour integrals and integral transformations. Fredholm integral equation of the second kind with a compact operator in Hilbert space L2 is obtained. The comparison with known results and limit variants is given. The effectiveness of the constructed algorithm is confirmed. Some generalizations of the problems are considered


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16.  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 853 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


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17.  Theoretical investigation of photonic crystals by means of analysis of photonic density of states maps
I.V. Guryev
photonic crystal, photonic density of states, transmittance spectrum, plane wave expansion method, Finite differences method
Vestnik KhNU 853 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


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18.  Paramagnetic properties of ASO2" free radical in irradiated KDP single crystals
A.N. Levchenko
KDP single crystal, ionizing irradiation, Free radicals, EPR, spin Hamiltonian
Vestnik KhNU 853 Pages. 84-87

The electron paramagnetic resonance (EPR) spectra of AsO22- free radical in potassium dihydrogen phosphate (KDP) single crystals irradiated with gamma rays and electrons have been investigated. The angular dependences of the spectra have been measured. The number of magnetically inequivalent sites for the AsO22- in the crystal lattice of KDP has been determined. The principal values of g-factor and hyperfine structure tensor have been calculated. It is found that the radical exhibits orthorhombic symmetry. The lagest component of hyperfine tensor is in the ab crystal plane. The molecular planes of the free radicals and the ab crystal plane are mutually perpenducular. The superhyperfine structure of the spectra indicates an existence of two protons near the paramagnetic center


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19.  HF ionosonde signal focusing by traveling ionospheric disturbances
Yu. B. Milovanov, V. F. Pushin, O. F. Tyrnov
traveling ionospheric disturbances, signal amplitude variations, Doppler frequency shift, Focusing factor, computer simulation
Vestnik KhNU 853 Pages. 88-94

HF signal focusing due to linear and nonlinear wave disturbances occurring during monostatic ionospheric sounding is discussed. A technique is developed for estimating signal amplitude variation due to focusing based on beating amplitude measurements during significant Doppler frequency shift events. The intercomparison of measured and modeled variations in beating amplitudes, the focusing index, and Doppler frequency shift show a qualitative agreement. The simultaneous analysis of variations in the beating amplitude and the Doppler frequency shift makes the interpretation of measurements more definite, e.g., it permits the isolation of large scale disturbances traveling at approximately 1 km/s


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20.  Experimental study of diffraction of electromagnetic waves on the lattice of elements of the complex profile
Ivanchenko D.D., Maleev M. N.
the difraction electromagnetic waves, chiral grates, Frequency-poiarization property
Vestnik KhNU 883 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 surfac


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21.  Microstrip structures with photonic band gap
Fesenko V.I., Sukhoivanov I.A., Shul'ga S.N.
photonics band gap, microstrip, Filter
Vestnik KhNU 883 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


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22.  

photonics band gap, microstrip, Filter
Vestnik KhNU 883 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.


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23.  Impact of random variations of air hole diameters and random variations of the centers position of air holes on operation parameters of a solid core microstructured optical fiber
A.I. Filipenko, A.N. Donskov
Finite-element method, Gaussian distribution, inclusions diameter, total mode field power, angular positioning, microstructured optical fiber.
Vestnik KhNU 983 Pages. 29-32

We investigated the impact of random variations of air hole diameter and random variations of the centers position of air holes on operation parameters in the case of solid core microstructured optical fiber with a ring of air holes. The found results show that at any of considered defect types mode field will have two pronounced maximums. At practical use an investigated type of the MOF special angular positioning end faces of fibers is necessary. We also have shown that random variations of inclusions diameter can increase total mode field power. In our research we used finite-element method.


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24.  

holography, physiological optics, retina, uniaxial crystal, Form-birefringence, Fresnel's formulas.
Vestnik KhNU 983 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.


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25.  

plane dielectric waveguide, inverted dielectric waveguide, Fourier transformation, Fredholm integral equation, dispersion equation.
Vestnik KhNU 927 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.


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26.  

radioholographic image, Flat and unflat radiohologram, by volume image of object, effect of Dopler.
Vestnik KhNU 927 Pages. 48-53

The physical and structural features of construction of the radioholographic informative systems (RG IS) and their adaptive properties which show up at forming and treatment of the coherent wave field on a transmission and reception are examined. The method of registration of radiohologram is offered on the surfaces of arbitrary form and method of adaptation of frequency of supporting oscillation to different frequencies of signal at a cooperative reception and to frequency of Dopler.


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27.  

DKDP single crystals, dc electrical conductivity, concentration of L-defects, gamma -irradiation, First order kinetics.
Vestnik KhNU 927 Pages. 22-30

The dependence of electrical dc conductivity of KD2PO4 (DKDP) single crystals on the dose of ?-irradiation is investigated. The conductivity is found to decrease exponentially in a dosage range of 3.0 1022.8 104 Gy. The temperature dependences of the conductivity are described by the exponential law. The pre-exponential factor and activation energy values of conductivity are determined for the crystals irradiated with various doses. Analysis of the dose and temperature dependences shows that the radiation-induced decrease of the conductivity is associated with the decrease of L-defect concentration in the crystal. The concentration changes in accordance with the law of first order kinetics. Possible mechanisms of the L-defect concentration changes under gamma -irradiation of crystals are discussed.


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28.  

stratified structure, chirality, Fibonacci sequence.
Vestnik KhNU 927 Pages. 15-21

Optical properties of both symmetrical and asymmetrical modified Fibonacci structures of chiral and achiral isotropic layers are studied. The localization and polarization transformation of linearly polarized waves are considered. The effect of the phase shift compensation in the reflected field is shown in the case of an asymmetrical modified Fibonacci multilayer and on the basis of the developed software the series of computing experiments testifying to perspective of use of such structures in optical systems.


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