2006, volume 11, ¹ 2
INFLUENCE OF RANDOM BULK IMPERFECTIONS ON THE MICROWAVE QUASI-OPTICAL RESONATOR SPECTRUM. I. STATISTICAL ANALYSIS
Ganapolskii E. M., Eremenko Z. E., Tarasov Yu. V.
171-179
Statistical analysis of oscillations in SHF cavity resonator filled with random dielectric imperfections is performed. The imperfections have negligibly small dissipative losses and result in essential shift and widening of spectral lines. We relate this effect to stochastic intermode scattering of waves on imperfections. It is supplementary to dissipative widening caused by ohmic losses. The shift and widening of each spectral line depend essentially on frequency interval between this line and nearest lines of the spectrum. On increasing the interval, the influence of imperfections reduces substantially. This results in essential spectrum rarefaction. The rarefaction is due to the fact that solitary spectral lines are to minor extent subjected to the influence of imperfections and preserve their high quality factors. At the same time, the Q-factors of adjacent lines change substantially. As a result, when exciting the resonator, only sparse lines with high Q-factors dominate in the spectrum.
MODE-MATCHING METHOD MODIFICATIONS IN THE PROBLEM FOR A CIRCULAR TO RECTANGULAR T-JUNCTION
Perov À. O., Senkevich S. L.
180-189
The new mode-matching scheme for the problem of a circular to rectangular t-junction is proposed. For solving, the technique of using virtual resonator is used. The algorithm is realized in such manner that intermediate variables can be eliminated analytically. The advantage of this approach is that it enables mode basis of virtual cavity to be set in unique way by choosing only the modes which have non zero coupling coefficients with both circular waveguide modes and rectangular ones. The ways of effective realization are considered which are connected to analytical inclusion of intermediate matrix inversions and symmetry of the junction. The proposed scheme is realized and verified with known result.
ON THE WEAK EFFECT OF ROUNDING-OFF THE CORNERS IN THE COMB SLOW-WAVE STRUCTURE RESONATORS UPON THE COMB DISPERSION CHARACTERISTICS
Mil’cho M. V.
190-195
An effect of rounding-off the resonator cavity corners upon the resonator electrodynamic characteristics is theoretically studies. The method of comparing between the electrodynamic and electrostatic solutions is applied for analysis. It is shown that in the long-wave approximation the corner rounding-off does not essentially haw an effect on rectangular resonator characteristics. This conclusion is confirmed experimentally.
SLOT RESONANCES IN AXIALLY SYMMETRICAL RADIATORS OF PULSED AND MONOCHROMATIC TM0N- WAVES
Sirenko K. Y.
196-204
Slot resonances of TEM-waves in narrow circular and circular coaxial waveguides have been studied, whose excitation allows one to control efficiently the electrodynamic characteristics of classical axially symmetrical radiators.
INTENSITY SPECTRUM OF THE OUTPUT SIGNALS OF THE DIFFRACTION RADIATION OSCILLATOR WITH QUARTER-WAVE (REFLECTIVE) DIFFFRACTION GRATING
V. G. Kurin
205-209
The question about the capture of a part of the fast waves energy by the periodic structure (diffraction grating) placed on one of the open resonator mirrors is considered in this article. It is shown, that cases of energy capture are physically equivalent to the energy losses of the fast waves leaving as a surface waves of the periodic structure from interaction space. During the combined frequency tuning the energy capture of the fast waves by the homogeneous diffraction grating is repeated almost periodically, that causes corresponding modulation of the output signals intensity spectrum (P=Ô(f)) of the generator. It is shown, that at higher mode excitation in the generator resonance system the offset from lines j = 2p, characteristic for cases of a diffraction radiation regime in area of the p- kind existence, are observed. These deviations represent cases of the diffraction generator oscillation excitation in modes of a backward wave oscillator on a volume waves.
CONE-SHAPED QUASI-OPTICAL DIELECTRIC RESONATORS
Barannik A. A., Bunyayev S. O., Cherpak N. T.
210-214
Possibility of whispering gallery modes excitation in the dielectric resonators made in the form of truncated cone both with and without conducting endplates is experimentally shown when angles of the generatrix with respect to longitudinal axis of the resonator changes up to 35°. Dependences of eigen frequency, quality factor and electric field distribution depending on a slope angle of the generatrix of cone are obtained in Ka-band. Comparison of eigen frequencies and quality factors of various kinds of cone-shaped resonators and hemispherical one is carried out. It is shown that quality factor and including coefficient of conducting endplate for conical and hemispheric resonators are equal at slope angles of the generatrix ~ 6 - 8°.
ABSORPTION OF WAVES BY THE GRATE FILLED BY METAMATERIAL WITH NEGATIVE PERMITTIVITY
Kusaykin O. P., Melezchyk P. M., Poyedynchuk A. Yu.
215-221
The theoretical analysis of electromagnetic properties of the reflecting diffraction grate filled by media with negative permittivity is presented. The resonance absorption effect of the excitant electromagnetic field energy by such structure is explored in the wide range of the parameters change. The effect of breaking up of absorption resonances in the case of the sloping falling of plane wave on a structure is shown.
EXPERIMENTAL RESEARCHES OF NON-UNIFORM PATH’S INFLUENCE ON AZIMUTH ERRORS OF BEARING
Gontar I. D., Kivva F. V., Razskazovsky V. B., Sinitsky V. B., Shul’ga V. F.
222-228
The results of experimental researches azimuth errors of bearing over the land, caused by turbulent troposphere and rough surface, are discussed. It is shown, that for a case when the angle of arrival is commensurable with the receiving antennae diagrams, errors of bearing are determined, in general, by rough surface.
DOPPLER-POLARIMETRIC PARAMETERS OF TURBULENCE IN PRECIPITATION ZONE
Marchuk V. V., Yanovsky F. J.
229-233
Influence of dangerous meteorological objects on aviation safety is considered. Main Doppler-polarimetric characteristics are shown. Article describes method of calculation parameter SLP–tangent of inclination angle of spectral differential reflectivity, which is a function of both – precipitation structure and turbulence. Interconnection between turbulence intensity and value of SLP is exposed. Equation and algorithm are represented. Perspectives of using these parameters and especially SLP in creating multi-parameter expert system based on fuzzy logic are shown.
THE RADIOBRIGHTNESS TEMPERATURE DEPENDENCE FROM RADIO WAVE PROPAGATION CONDITIONS AT GRAZING ANGLES ABOVE SEA SURFACE
Kabanov V. A.
234-239
The results of experimental investigations of radio wave propagation condition influence on atmosphere radiobrightness temperature at grazing angles above sea surface are presented. The parameters of radiobrightness temperature elevation profile well agreed with propagation factor on beyond the radio horizon tested path are determined. The prospects of usage of the radiobrightness measurements at grazing angles for radio wave propagation condition estimation is shown.
VIDEOPULSE ELECTROMAGNETIC WAVE DIFFRACTION ON SUBSURFACE OBJECTS
Varyanitza-Roshchupkina L. A., Pochanin G. P.
240-252
The way for solving the problem of subsurface ultra-wideband (UWB) baseband radar that is based on using the finite difference method is presented. The difference scheme Yee and «precise» absorbing boundary conditions limiting the principally open region under consideration have been used for effective realization of the given method. Corresponding GPR images of trenches with buried metal pipes have been obtained and analyzed on the basis of electrodynamic simulation of UWB pulse electromagnetic wave scattering problem.
TRANSITION RADIATION NONSTATIONARY PULSES BY AN ELECTRON BUNCH THAT CROSSES AN INTERFACE OF A VACUUM - PLASMA
Averkov Yu. O., Yakovenko V. M.
253-261
The possibility of transition radiation of nonharmonic nonstationary pulses by an electron bunch that crosses an interface of a vacuum – plasma has been shown. It has been established that for a dense plasma, when the plasma frequency higher than the cutoff frequency, the amplitudes of nonstationary harmonics are not exponentially small values. The excited nonstationary pulses have cylindrical symmetry and the energy transfer in a dense plasma has mainly the normal direction to the interface.
MAGNETORESISTANCE OF MAGNETIC TUNNELING JUNCTION WITH STEP-LIKE POTENTIAL BARRIER
Beletskii N. N., Borysenko S. A., Yakovenko V. M.
262-269
The influence of the bias voltage on the magnetoresistance of a magnetic tunneling junction with a step-like potential barrier has been studied theoretically in the frame of a two-band model of free electrons in ferromagnetic electrodes. It is shown that the dependence of the magnetoresistance of the magnetic tunneling junction on the bias voltage can be different according to the type and the thickness of the isolators forming a step-like tunneling potential barrier. It has been found out that the magnetoresistance of the magnetic tunneling junction can change its sign and oscillate with increasing bias voltage. It has been shown that the sign reversal of the magnetoresistance is related to the increase in the transmission coefficient of majority electrons through the magnetic tunneling junction as the mutual orientation of magnetization of ferromagnetic electrodes switches from parallel to antiparallel.
HCN-LASER WITH A HYBRID OUTPUT MIRROR
Kamenev Y. Ye., Masalov S. A., Filimonova A. A.
270-274
A waveguiding HCN-laser with the active medium 1m long has been studied. An output mirror of the laser includes a coupled one-dimensional wire grating and a flat mirror with a porthole. The dependence of the laser radiation power on the porthole diameter, grating’s period and the distance between the mirror and the grating has been investigated experimentally.
THE DIODE ELECTRON GUN WITH SLIT L-CATHODE
Belousov Ye. V., Zavertanniy V. V., Nesterenko A. V.
275-280
The diode electrooptical system (EOS) is designed for high current density electron streams creation is presented. The slit L-cathode formed in the line of joint of lateral surfaces of two materials with different structure. Emission current extraction and electron stream forming occurs in inhomogeneous electric field when EOS arranges in close to uniform magnetic field. The cathode system is developed and produced; the results of experimental research of its features in the range of accelerating voltages 0.5 ¸ 2.5 kV are given. Conclusions about availability of the EOS formed electron streams for electromagnetic oscillators in short millimeter wavelength range are drawn.
RESEARCHES OF SPECTRA OF SPATIAL FREQUENCIES FOR PROBLEM SOLVING OF A FOCUSING
Dzyubenko M., Kolpakov S., Priyomko O.
281-285
The method of a focusing of objective, based on the analysis of spatial spectrum images, is circumscribed. Its theoretical substantiation is presented. It is shown, that for a surface of any object there exists of one or several resonant spatial frequencies, which have maximum intensity in a focal point. It is connected to a method of formation of a roughness. On the base of theories of stochastic and random oscillations it is asserted, that all real rough surfaces are not absolute random in a sense of a theory of probabilities. Therefore, optical fields generated by these objects are not random too. The image in this case is the result of interactions of a field with a screen. Such submission has allowed us to use correlation dimensionality of spatial chaos of an optical field as its characteristic. The conducted researches have allowed us to combine process of precision guidance of the technological laser on a focal point with obtaining of a sharp image of a treated surface.
THE EMISSION SPECTRUM KINETICS OF THE PULSED DYE LASER WITH THE COAXIAL CELL PUMPED ON INSIDE
Nikolaev S. V., Pozhar V. V.
286-290
The formation and evolution regularities of the spectral characteristics of dye laser on rhodamine 6G with coaxial active element, excited from within, were studied in this work. For this the dependences of the emission spectrum kinetics on dye concentration in the active solution and energy of pumping were investigated experimentally. The calculations of the refractive index distribution according to the cross section of active element were made for the purpose to the explanation of the special features of radiation spectra evolution. It is shown that the laser with the coaxial active element, excited from within, can emit radiation with the stable spectrum during entire pulse when the intensity of pumping radiation in the peripheral zone of cell is small.
CURRENT-VOLTAGE CHARACTERISTICS’ WIDTH OF INXGA1-XN GUNN DIODES
Pavlenko D. V., Prokhorov E. D.
291-297
Impact ionization in GaN, InN and their combinations is considered, the current-voltage characteristics’ width and voltages enough for impact ionization development in Gunn diodes made of GaN, InN and their combinations are defined.
EXPERIMENTAL INVESTIGATION OF P-BAND CHAOS GENERATOR
Zemlyaniy O. V.
291-297
The results of experimental investigation of chaotic waveform generator of P-band are presented in this paper. Operation of the generator is based on chaotization of self-oscillations in the nonlinear dynamical system with delayed feedback of ring structure. Asymmetric piecewise linear one-dimensional map with tunable in experiment parameters is built as a nonlinear module. Statistical and spectral properties of the output signal as well as their relationship to the parameters of nonlinear element have been studied. The obtained results can be used for design of chaos oscillators with prescribed properties of output signal.
EMPLOYMENT OF DETECTION – MEASURING METHODS FOR THE MULTIRAY CHANNELS CHARACTERIZATION ANALYSES
Popov I. V., Lutsenko I. V., Lutsenko V. I.
305-308
The detection – measuring the parameters of multielement target against a background of non-Gaussian noise task solution were considered. The situations when the signal detection is carried out in the multiray channel that conditioned on reflection from underlying surfaces (land, sea), or elevated inversion layers in the troposphere can be modeled of the multielement target. The correlated non-Gaussian noise is described of Markoff process with given transition probability density and unconditioned density of distribution. Such model is characteristic for noise that is created of reflection from sea surface, areas of land are covered of vegetation, elevated inversion layers in the troposphere at the radar resolution elements smaller then characteristic nonuniformity scale on the surface (mean sea wave-length, for example). The model is explaining the interference phenomenon in a propagation channel is proposed. The number of sources determination and source characterization based on the approach that is developed of the S. Ya. Fal`kovich`s school for the unknown quantity of the signals resolving – detection. However in contrast to proposed deterministic method that employed for the determination of signal number nulling the Gramm matrix determinant we employ the Fisher criteria for the significance estimation of signal source number.
FM SIGNAL FILTERING METHODS BASED ON ROBUST AMPLITUDE ESTIMATION AND CLIPPING TECHNIQUE
Roenko A. A.
309-317
The analysis of FM signal distribution law is done. Based on it two novel FM signal amplitude estimates are proposed. They can be implemented both in case of Gaussian and non-Gaussian heavy-tail noise environments. Developed algorithms for amplitude estimation are assumed as a basis for two FM signal reconstruction methods. Comparative analysis of obtained methods and known approaches based on the scanning window nonlinear filtering and robust DFT is performed. It is shown that the use of proposed methods allows increasing the FM signal filtering quality in comparison to the known approaches.
THING FILM HIGH TEMPERATURE SUPERCONDUCTIVITY COPLANAR LINE INVESTIGATION
Bondarenko N., Lavrinovich A. A.
318-322
Possibility of the high-temperature superconductor planar microwave line section as the device for protection of electronic systems from pulse electromagnetic signals is considered. The experimental research of behavior of a thin-film coplanar line section (YBa2Cu3O7-x on sapphire) is carried out under the influence of the microwave pulses of various power and duration. Transition in a resistive state is observed, and also growth of losses is fixed at increase of pulse duration.