2011, Vol. 2(16), № 2
WAVE INTERACTION IN A WAVEGUIDE SECTION WITH SHARP CORRUGATION
V. A. Goryashko, T. M. Slipchenko, Yu. V. Tarasov
Using rigorous excitation equations we have analyzed the wave propagation in a rectangular waveguide section with sharp corrugation, the ratio of the corrugation height to its period is much more than unity. We have shown the strong gradient scattering to result in that the Brillouin diagram of the corrugated and regular waveguides have the same character of the longitudinal wave number–frequency dependence. The difference is just that the cutoff frequencies of the corrugated waveguide modes increase with decreasing of the corrugation period and there can be always realized single-mode regime in the arbitrary frequency region that is located higher than the first cutoff frequency. The phenomenon can be used for suppression of the mode competition in microwave amplifiers as well as in the narrow-band generators, if Bragg reflectors are used there as feedback.
SOURCES ESTIMATION IN THE 1-D ARRAY OF ELECTRIC DIPOLES BY USING PRINCIPLE OF MINIMUM SPATIAL EXTENSION OF SOLUTION
V. F. Borulko, S. M. Vovk
Vector model of sources described by a sequence of ideal Hertz dipoles with their common dipole moment orientation is considered. By using a principle of minimum spatial extension of solution the problem of sources estimation is formulated and approach based on conjugate gradient method with special selection of step value along descent direction is proposed. Numerical simulations for the case when sources are real and located along a straight line paralleled to measurement line are presented.
ELF TRANSIENT AT KARYMSHINO ASSOCIATED WITH EXTRA-GALACTIC
GAMMA RAY BURST OF 27.12.04
A. P. Nickolaenko, A. Yu. Schekotov
Results are given of observations of electromagnetic pulse associated with an abrupt change of the height of the Earth–ionosphere cavity that was caused by intense gamma ray burst of December 27, 2004. We demonstrate that parameters of observed extremely low frequency (ELF) radio pulse correspond to expectations: the source bearing is close to the direction toward the epicenter of ionosphere modification, the pulsed waveform is similar to that computed, and its amplitude exceeds the level of regular Schumann resonance background by a few times. Simultaneously, the pulse onset at the Karymshino observatory (52,827° N, 158,132° E) is ~ 0.16 s in advance relative to the published time of modification in the VLF records.
ABOUT THE DECAY INSTABILITY OF THE ELECTRONIC WAVES IN VAVILOV-CHERENKOV EFFECT
S. I. Khankina, V. M. Yakovenko
The decay instability effect at the interaction of electronic waves with electromagnetic and electrostatic waves has been studied in material media. The corresponding expressions for the instability increment are obtained. It is shown that the Vavilov-Cherenkov effect can be represented as a scattering process of inelastic scattering of electrons on the electron-induced waves.
ELLIPSOIDAL PROPERTIES OF REFLECTIVITY FROM THE FINE-STRATIFIED SEMICONDUCTOR – DIELECTRIC PERIODIC STRUCTURE IN A MAGNETIC FIELD
A. A. Bulgakov, I. V. Fedorin
Polarization of an electromagnetic wave in the case of reflection from the fine-stratified periodic structure located on a metal substrate is investigated. The structure was fabricated by periodic alternating dielectric and semiconductor layers and was exposed into an external magnetic field. It has been shown that changing the magnetic field, frequency and incident angle results in change of polarization ellipse parameters, lengths and inclination angles of an ellipse axes in relation to axes of coordinate system. Taking into account losses in the semiconductor layers result in smoothing of dependences and absence of dramatic change of polarizing characteristics depending on an external magnetic field and frequency.
DEPENDENCE OF FREQUENCIES OF THE SURFACE ELECTROMAGNETIC STATES IN PHOTONIC CRYSTALS ON PARAMETERS OF DUOBLE-LAYERED DIELECTRIC ELEMENTARY CELL
Yu. O. Averkov, N. N. Beletskii, V. M. Yakovenko
In this paper, we present the theoretical analysis of surface electromagnetic states (SES) at the interface between a photonic crystal and a plasma-like medium. It was assumed that an elementary cell of the photonic crystal is composed of two different non-magnetic dielectrics. The change of frequencies of SES with the configuration of the elementary cell has been studied. We have shown that at certain parameters of the elementary cell a number of SES can exist. These states differ in frequencies and their electromagnetic field localization in the photonic crystal and in the plasma-like medium. The possibility of existence of SES in metal-photonic crystal structures with layers of SiO2 and Si has been demonstrated. These structures are widely used for up-to-date applications of silicon nanophotonics.
Yu. V. Kornienko
The problem on the optimal filtering of images from the finite-dimensional functional space which are blurred by a known kernel and recorded in the presence of additive Gaussian noise, is considered from the standpoint of the Bayes statistical approach. A general view on the problem is illustrated by two specific practical problems: filtering of images of an extended source system of known shape, and determination of coordinates of a point source and its intensity as a time-varying function against the uniform background of unknown brightness.
STUDY OF EMISSION FEATURES OF SOLID-STATE DYE LASERS AT A TRANSVERSE METHOD OF EXCITATION
S. V. Nikolaev, V. V. Pozhar, M. I. Dzyubenko
In this work the special features of the formation of emission characteristics of solid-state dye lasers with the transverse pumping are studied. The dependences of energy, spectrum and directivity of the emission from cylindrical polyurethane laser matrices on energy and degree of the exciting beam focusing are experimentally investigated. It is shown that the inhomogeneity of the pumping intensity distribution in the excitable matrix volume, which appears at a transverse mode of excitation, renders significant influence on the energy, directivity and spectrum of laser emission.
SLOW WAVES IN A PERIODIC STRUCTURE WITH MAGNETOACTIVE SEMICONDUCTOR LAYERS
A. A. Bulgakov, V. K. Kononenko
Features of zone spectra of the periodic structure with magnetoactive semiconductor layers in the vicinity of its characteristic frequencies in submillimeter wavelength range were studied theoretically. It is shown that the surface wave phase velocity in the thin-layer periodic structure with transverse external magnetic field configuration can be comparable to the charge carriers drift velocity in the semiconductor. Thus, a calculated coefficient of wave delay can exceed 103 in the periodic structure with nano-layers of celsian ceramics and n-InSb at liquid-nitrogen temperature at the magnetic fields 0,25…1 T. A physical reason for wave delay is connected with existence of the lowest frequency pass band of the thin-layer periodic structure allowing promotion along dispersion curve into the region of high values of the wave number modulus for a small period of the structure.
B. P. Yefimov, A. N. Kuleshov, S. S. Ponomarenko
The experimental results on research of transitional radiation excited by electron bunches, which are scattered on periodic inhomogeneities in the form of a wire ladder structure have been presented. The modulator (generator of electron bunches) created by resonant backward wave oscillator in 8 mm band is described. It is shown that measured transition radiation pattern is in good agreement with theoretical calculations.
EXPERIMENTAL ESTIMATION OF INTERFERENCE IMMUNITY OF THE NOISE PULSE SHORT RANGE RADAR AFFECTED BY CONTINUOUS ACTIVE INTERFERENCES
K. A. Lukin, V. M. Kantsedal, V. V. Kulyk, V. M. Konovalov, A. A. Mogyla, V. P. Palamarchuk, P. G. Suschenko
Estimations of interference immunity of the correlative receiver of short uncorrelated noise pulses consequences with a wide power spectrum (bandwidth-duration product ~ 50…100) are presented in the conditions of influence of continuous active interferences: noise one with a concentrated wide power spectrum, monochromatic one and their mixture. Character and degree of their influence are specified for the output signal of explored correlative receiving. Besides, influences of differences of spectral and power parameters of useful noise signal and interferences on receiver immunity are investigated particularly at the small values of input signal/interference ratio. Estimations of thresholds of correlative receiver immunity are determined with the set of statistic immunity indexes for the change of mutual correlations functions form.
HEMISPHERICAL DIELECTRIC RESONATOR WITH CONCENTRIC HEMISPHERICAL HOLLOW FOR LIQUID DIELECTRICS INVESTIGATIONS
A. Ya. Kirichenko, A. E. Kogut, V. V. Kutuzov, I. G. Maksimchuk, S. O. Nosatyuk, V. A. Solodovnik
A new type of cell was suggested for dielectric constant measurements of liquids. Next liquids were investigated: methanol, butanol, toluol, benzol and water. It is shown that these resonators are suitable for research of dielectric properties of liquids.