2011, volume 16, № 1
SYSTEMS APPROACH TO INVESTIGATION OF PREFRACTAL DIFFRACTIONAL GRATINGS
G. I. Koshovy
3-10
The article deals with electro magnetic theory of prefractal diffractional gratings (PFDG). Much attention is given to systems analysis of two classes of self similar fractals with variable Hausdorf’s dimension, which is the base of PFDG’s order. Same mathematical models of electromagnetic waves scattering by PFDG are presented. An asymptotical model of weekly filled PFDG is considered in details. The model is effective to examine of fractal properties.
PARAMETER SELECTION IN PARTICLE SWARM OPTIMIZATION ALGORITHM FOR SYNTHESIS OF LINEAR ARRAYs WITH FLAT-TOP BEAMS
A. Yu. Galan, A. V. Boriskin
11-18
An efficient global optimization algorithm based on the Particle Swarm Optimization approach is developed and applied for synthesis of a linear antenna array with a flat-top beam. A flowchart of the algorithm is provided along with a discussion on the impacts of different factors affecting the algorithm performance, namely its convergence rate and stability in hitting the global extremum. Finally, the optimal values of the algorithm parameters (weight coefficients and boundary condition type) for the considered problem are determined via systematic study.
MICROWAVE EFFECTIVE ELECTROMAGNETIC RESPONSE OF SANDWICH LIKE MAGNETIC COMPOSITE
O. N. Rybin, A. I. Pitafi, S. P. Vyalkina
19-23
In this study, the long wave approximations for the effective electromagnetic response of 2-D sandwich metamaterial structure, as infinite two-component flat composite with cylindrical metallic inclusions contained by the same infinite two-component flat composites with spherical metallic inclusions are obtained. The expressions for the response are obtained by generalizing the expressions of the electromagnetic response of the infinite chain of infinitely long metallic cylinders periodically immersed in the flat magneto-dielectric matrix. The generalization has been done by following the approaches of S- and T-matrices. The case of ferrite like metallic saturated inclusions is considered in the study. The analytically obtained results are compared with the numerically calculated ones.
THE DEPHASING OF EIGEN-MODES OF A QUASIOPTICAL CYLINDRICAL RESONATOR WITH RANDOMLY INHOMOGENEOUS SIDE BOUNDARY
E. M. Ganapolskii, Yu. V. Tarasov, L. D. Shostenko
24-32
The spectrum of quasi-optical cylindrical resonator with randomly inhomogeneous side surface is calculated for the first time. To solve this problem, the novel method of mode separation in wave equation is developed, which is based on the operator technique. The effect of random inhomogeneities on the resonator spectrum is described in terms of single universal gradient parameter Ξ allowing for the degree of «sharpness» of surface inhomogeneities. It is shown that the shift and the broadening of a spectral line, which results from the dephasing of resonator modes due to their scattering by inhomogeneities, is proportional to the dissipative broadening. The numerical experiment is performed, which reveals that without accounting for the dissipation loss the spectrum of a random-inhomogeneous cylindrical resonator is regular, whatever the level of boundary inhomogeneity, but possesses quite different statistical properties in the case of small and large values of parameter Ξ.
USE OF MICROSTRUCTURE PARAMETERS FOR DATA PROCESSING OF DOUBLE FREQUENCY MEASUREMENT OF RAIN INTENSITY
A. M. Linkova
33-38
Results of study of double frequency method for measurement of rain intensity using three-parameter gamma distribution of drop sizes are presented. For elimination of measurement ambiguity of distribution parameters using data of double frequency sounding the use of data of contact measurement of connection between rain intensity and gamma distribution parameters was proposed. The results of calculations performed by Mie theory were presented, they allow to estimate applicability of proposed method for polydisperse medium and to give references for choice of frequency range for double frequency radar.
APPLICATION OF THE SPECTRAL INTERFEROMETRY METHOD FOR MICRO- AND NANODISTANCES MEASUREMENT
K. A. Lukin, Yu. P. Machekhin, M. B. Danailov, D. N. Tatyanko
39-45
The paper presents some results of the optical inter-ferometry investigations with use of low-coherent optical sources beyond their coherence zone. It is shown that when the path difference of arms in Michelson interferometer exceeds the coherence length of light-emitting diode radiation, the interference pattern in spectral domain enables to perform absolute measurements of micro and nano distances due to its dependence on both time delay and relative phase of the signals.
DECOMPOSITION OF THE LASER-INDUCED EMISSION SPECTRUMS
M. I. Dzjubenko, D. F. Kulishenko, A. A. Priyomko, S. N. Kolpakov
46-49
Presented paper deals with splitting of laser-induced spectrums into set of standalone spectral bands. Model of spectrum is created, different shapes of band are examined and comparison is presented.
HCN-laser application for measurement of one-dimensional wire gratings phase characteristics
S. A. Andrenko, Yu. E. Kamenev
50-53
A new method of determining the phase shift of electromagnetic waves transmitted through the one-dimensional wire grating with its normal incidence on the grating. To implement the proposed method HCN-laser was applied, which is widely used as a source of radiation in the THz range. The output mirror of the laser was made in the form of the grating and the solid mirror with an aperture. Methodologically this method is based on determination of the difference in the length of the laser resonator with sequential generation at two polarizations: parallel and perpendicular to the wires of the grating.
IMPEDANCE CHARACTERISTICS OF DIODES WITH TUNNEL AND RESONANCE-TUNNEL BORDERS
E. D. Prokhorov, O. V. Botsula, O. A. Klimenko
54-57
The impedance characteristics diodes having negative differential conductivity (NDC) in result of tunneling or resonance tunneling electron across diode lateral are considered. This NDC can be used for generation, amplifier and multiplication. The active and reactive parts of impedance versus frequency for real diode parameters are determined. It is shown that limiting frequency of NDC diode is corresponded to THz range and depends on diode parameters.
The respectives for using gunn diode on the base OF GaN, AlN AND InN
I. P. Storozhenko, Yu. V. Arkusha
58-63
Properties transfer, idealized limited space-charge accumulation mode and resonance transit-time mode of the GaN, AlN, InN n+–n–n+ and n+–n––n–n+ Gunn diodes were studied. Prospects, peculiarities and problems of nitride semiconductors in Gunn diodes are represented.
About resonance frequency of Gunn diodes based ON graded-gap semiconductors AlGaAs, GaPAs and GaSbAs
I. P. Storozhenko, E. N. Zhivotova
64-69
The disappearance of a drifting domain in devices based on graded-gap semiconductors is studied. It is shown that the length of a region of drift of a the domain and the frequency of generated current oscillation in the n+-n-n+ devices based on graded-gap semiconductors depends on the voltage applied to the device. The conditions of existence of this effect are found. It is shown that the use of graded-gap semiconductors can increase the width of the width of the working frequency of Gunn diodes. The review of graded-gap semiconductors A3B5 having a similar effect is given.
PARAMETERS OF SECOND ELECTRON PROCESSES IN UNIFORM ELECTRIC FIELDS OF RF RESONATOR STRUCTURES
L. D. Lobzov
70-76
It is shown, that energies of the electrons emitted from surfaces of electrodes of the diode gap unit resonator cell, are spotted not only amplitude and a phase of the voltage enclosed at this moment, but also dynamic quality factor of cell Q. At Q >> 1, in an initial part of a half-period of a voltage when the instantaneous values of its amplitudes are small, terminating energies of the accelerated primary electrons transmitted other electrode, also are small. Thus its secondary electron emission properties caused by specified quantities of energies, are characteristic by coefficient of secondary electron emission d more unities (d > 1). In the subsequent part of a half-period of a voltage, the instantaneous values of its amplitudes and, accordingly, energies of the accelerated primary electrons, more initial. And secondary electron emission properties of electrodes are characterized by coefficient d less unities (d < 1). Change of a quality factor of a contour from Q >> 1 to Q ~ 10…1 leads to essential waist of an interval of phases and a gamut of small energies of primary electrons in an initial part of a half-period of time. Thus the energies transmitted other electrode, characterized in the whole its secondary electron emission properties as d < 1.
SUBMILLIMETRIC-WAVE RANGE REJECTION FILTER OF LATERAL HYBRID MODES IN HOLLOW DIELECTRIC WAVEGUIDE
A. I. Goroshko, V. K. Kiseliov
77-80
The breadboard modes of a rejection a circular hollow dielectric waveguide has been analyzed and experimentally studied. The filter is a waveguide segment bounded by two planar one-dimensional wire grating. This type of filter suppresses spurious modes down to 15…20 dB, us the operating HE11 mode gets damped down to 3 dB at 300 GHz in a waveguide of diameter 20 mm.
INDENTIFICATION OF POTABLE WATER FROM KHARKOV REGION SPRINGS, USING TEMPERATURE DEPENDENCE OF THEIR REFRACTION INDEXES
A. Ya. Kirichenko, G. V. Golubnichaya
81-84
Refraction indexes of water samples from different springs and their dependencies upon temperature are studied in millimeter wavelength using oscillating string method. It is established that temperature dependence of refraction index in the investigated range of temperatures can be approximated by linear dependence. It is shown that coefficient of the linear regression of temperature dependence allows one to distinguish waters from different springs.
OPTICAL SPECTRAL TUNING IN QUANTUM-CASCADE STRUCTURES FOR SPECTROSCOPIC SENSING OF EXPLOSIVES
S. I. Petrov, M. V. Klymenko, O. V. Shulika
85-90
In this paper we propose a new approach to spectral tuning in quantum-cascade structures. Based on phase space filling effect, spectral tuning is accompanied by the continuous optical pump. According to mathematical modeling of optical properties of quantum cascade-structures, proposed method allow to realize tuning in the range up to 1.1 meV without significant changes of peak gain magnitude. Obtained results are of interest for spectroscopic sensing of explosives.
MEASUREMENT OF COMPLEX PERMITTIVITY OF LIQUIDS USING OPEN-ENDED COAXIAL-LINE AND METAMATERIAL SUBSTRATE
V. K. Ivanov, O. O. Silin, O. M. Stadnyk
91-98
Modification of the method for determination of complex permittivity of liquid media by open-ended coaxial line probes, based on using metamaterial substrate with known characteristics, is proposed. It is shown, that under certain relations between electric parameters and thicknesses of media under test and substrate, resonance decrease of reflection from the end of probe loaded on such a two-layered structure, arise. Thus, determination of complex permittivity of media under test in wide range of its variation, being based on measurements of probe amplitude reflection coefficient only in finite frequency range in combination with fitting optimal thickness of tested layer is possible.