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1.  Identification and localization of radar impulses buried in noise
A. G. Tyzhnenko, Y. V. Ryeznik
radar, pulse, identification, localization, low SNR
Vestnik KhNU 806 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.

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2.  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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3.  Impedance characteristics of planar diodes with tunnel boundaries based on GaAs
Prokhorov E.D., Botsula O.V., Klimenko O.A.
: negative differential conductivity, tunnel boundary, a diode, the tunneling.
Vestnik KhNU 966 Pages. 13-18

The impedance characteristics of the diodes are consider, which negative differential conductivity (NDC) is arise under cer-tain voltage, due to tunneling of electrons through the side faces of the diode, which can be used for generation, amplification and multiplication. Depending on the active and reactive components of impedance are determined of the diode with the tun-nel boundaries for the real parameters of the diodes. It is shown that the limiting frequency of the diode NDC is in the tera-hertz range and depends on its parameters.

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4.  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

5.  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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6.  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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A.I. Adonina, V.B. Khokh
lattice, environment, dielectric, a stream of capacity, method of Riman-Hilbert problem
Vestnik KhNU 756 Pages. 51-56

The decision of a task in view is carried out for and the fields appropriate to two subsystems on which the system of the equations of the Maxwell for environments is divided. Integrated characteristics of a field are determined from the decision of systems of the linear algebraic equations received by a method of method of Riman-Hilbert problem , for a case when the smallest parameter decreases in inverse proportion to a square n->infinity. Programs (fort) with construction of diagrams are made. The analysis of the diagrams in part given in work, allows to establish influence of parameters of structure and corners of fall of a wave on anomalies in an absent-minded field for each concrete case

8.  Influence of impact ionization on efficiency of rsca-diodes operation on basis of InN, GaN, AIN
D.V. Pavlenko, E.D. Prokhorov
nitrides, RSCA oscillators, oscillating efficiency, drift velocity
Vestnik KhNU 756 Pages. 109-112

The impact ionisation in RSCA diodes is considered on the basis of nitrides InN, GaN, AIN. Possible overvoltage on diodes and possible efficiency of generation are analyzed. It is shown, that at development of a impact ionisation in RSCA diodes in correspondence with the diffusion theory the considered materials are perspective for RSCA diodes for operation in centimeter and millimeter wavebands (voltage over threshold 3 ... 5 at efficiency up to 11 ... 13 %)

9.  Influence of shading of the radiating aperture of single-reflector antenna by focal module on directional characteristics
Gorobets N.N., Kiyko V.I.
microwaves, reflector antennas, reflector shading, directional characteristics
Vestnik KhNU 966 Pages. 97-102

The effect of shading of the radiating aperture single-reflector parabolic antenna on radiation pattern, gain, wide beamwidth and sidelobe levels while changing the focal length of the relationship to the diameter of the reflector in the range of 0.5 to 1.5 takes place was theoretically investigated. Thus, it was shown that the effect of shading on all directional characteristics is the less than the longer-focused is the reflector. The minimum level of side lobes is in the case of short-focused reflector

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10.  Inner partial mutual admittance of two overlopping longitudinal slots in a rectangular waveguide with dielectric layer parallel to narrow walls
A.A.Lyakhovsky, L.P.Yatsuk, A.F.Lyakhovsky
, layer, dielectric, slot, admittance, scattering parameters
Vestnik KhNU 853 Pages. 22-27

The expression for the partial inner mutual admittance of two longitudinal slots overlapping along waveguide longitudinal axis is obtained. The slots are cut in a broad wall of a rectangular waveguide filled with three-layered dielectric. The excitation problem is solved with the modified eigen waves method. As eigen waves of the LE and LM modes are chosen. The field in the source region includes the potential functions as well. Dependences of inner mutual admittance and scattering parameters on distance between two slots and frequency are investigated. The system scattering parameters calculated are in a good agreement with experimental data

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11.  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

12.  Investigation of different temperature modes of auxilliary cathode work in magnetrons with cold secondary-emission cathode
Avtomonov N.I., Vavriv D.M., Sosnytsky S.V.
Magnetron, cathode, thermionic cathode, thermo emission, temperature
Vestnik KhNU 883 Pages. 73-82

A theoretical investigation of the emission current temperature dependence of the auxiliary cathode in magnetrons with cold secondary-emission cathodes is performed. Different methods of providing a spatial-charge limited emission from the auxiliary catho

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