RESONANT SCATTERING OF A PLANE ELECTROMAGNETIC WAVE BY FERRITE-STRIP GRATING-METAMATERIAL STRUCTURE
A. V. Brovenko, P. N. Melezhik, A. E. Poyedynchuk
3-12
Boundary value problem for plane electromagnetic wave diffraction by the ferrite-strip grating-metamaterial structure was reduced to Riemann-Hilbert problem with conjugation coefficient depending upon frequency of excitation wave and constitutive parameters of ferrite and metamaterial. Analytical regularization method was proposed to reduce this problem to infinite system of algebraic equations of the second kind with kernel matrix operator. Numerical analysis of frequency dependence of the reflection coefficient for the periodic structure was carried out. The frequency bands where the reflection coefficient exhibited pronounced resonant behaviour were determined. Excitation of the oscillations localized in the vicinity of media interfaces explains such resonant behaviour of the reflection coefficient.
SCATTERING OF H-POLARIZED WAVE BY PREFRACTAL DIFFRACTION GRATINGS
G. I. Koshovy
13-19
The article continues developing the bases of electromagnetic theory of prefractal diffraction gratings (PFDG). PFDG consists of strips, which are situated in a plane according to segments, which are еру same stage of self similar fractal with variable Hausdorf dimension. Statement of scattering problem for the H-polarized electromagnetic wave by PFDG is classically strict. By the integral equation technique, two dimensional external Neumann problem for Helmholtz equation transforms to one-dimensional problem of solution of integral-differential equations’ system and then to integral equations’ system. Method of the problem’s solution for asymptotical model of weekly filled PFDG is introduced. To show this model effectivity the case of two strips’ diffraction grating is examined in details. Numerical calculation of directional characteristics and their comparison with known results presented.
RESONANT INCREASE OF ELECTRICAL-TYPE EIGENMODE QUALITY OF AN OPEN RESONATOR WITH A SPHERICAL DIELECTRIC INSERT
Yu. V. Svishchov
20-26
A rigorous mathematical model has been built for describing electrical-type axially-symmetric eigenmode of a spherical-mirror open resonator with a spherical dielectric insert. The effect that the diffraction quality of resonator eigenmodes rises (falls) with varying geometrical and material parameters of the spherical insert has been found and investigated. The nature of the resonant change of eigenmode quality has been understood.
OPTIMIZATION OF A SOUNDING UWB PULSE SIGNAL DURATION IN A SUBSURFACE OBJECTS DETECTION PROBLEM
L. A. Varyanitza-Roshchupkina, G. P. Pochanin
27-40
Diffraction of a cylindrical pulse electromagnetic wave on the conductive cylindrical objects immersed in dielectric media of different conductivity is investigated by the use of computer realization of the finite-difference time-domain method (FDTD). The analysis and comparison of the scattered electromagnetic fields calculated at various values of an incident wave pulse duration and different distances between a field source, an observation point and an interface are carried out. Technique of determination of ultrawideband pulse sounding signal duration that is optimal for detecting subsurface objects is offered, and contrast of the signal reflected by object in relation to a total signal in an observation point is chosen as criterion of optimization.
FEATURES OF SPEKTRA OF RADAR REFLECTIONS FROM PRECIPITATION IN THE Ka-BAND
M. G. Balan, V. A. Zuykov, V. B. Razskazovsky, N. G. Reznichenko
41-45
The results of experimental study of Doppler spectra of radar reflections from rain and snowfall in Ka-band for horizontal and oblique sounding by coherent-pulsed signals are presented.
MILLIMETER WAVE PROPAGATION IN COASTAL AREA
V. Ivanov, Yu. Levadnyi, V. Shalyapin
46-52
The problems of centimeter and millimeter waves propagation over the sea in coastal area are considered. Ducts in the coastal area are usually advective and are sufficiently stronger than evaporation ducts. Their parameters (duct height and M-difference) depend on the distance to the shore. The field structure in the line of sight and the half-shadow regions were calculated by means of split-step parabolic equation Fourier method. The comparison of the calculations and experimental data have shown good agreement. It was also shown that interference structure of the centimeter wave field is stable and its distortion is possible only for very strong refraction. The distortion of interference structure for millimeter waves happens even for weak refraction and the interference structure are being destroyed for simultaneous strong refraction and changing radiometeorological parameters.
lightning location and estimation of the lower ionosphere EFFECTIVE HEIGHT using DISPERSION PROPERTIES OF tweek-atmospherics
A. V. Shvets, Yu. V. Gorishnya
53-59
A technique for distance finding to lightning discharges and the effective height of the lower ionosphere based on dispersion properties of tweek-atmospherics (tweeks), which propagate in the Earth-ionosphere waveguide during nighttime, is proposed. Examples of the distance (in the range from 500 to 2500 km) and effective ionospheric height estimation are demonstrated on experimental records of tweeks. Accuracy of estimations of the parameters in the proposed algorithm are obtained.
MATHEMATICAL MODEL OF THE RADAR IMAGE OF THE SHIP ON SEA
V. N. Gorobets, V. G. Gutnik, S. M. Zotov, F. V. Kivva, A. A. Shapiro
60-65
The mathematical model of radar image of the ship on sea is developed. It is shown that Doppler spectrum of the signal, reflected from the ship contains the information on architecture of the ship and dynamics of its movement. The offered model allows to reveal features of space structure of the ship. It allows to use it for the decision of some radar problems, including recognition of its radar image.
PECULIARITIES OF AUTOWAVE MOTIONS IN BOUNDED EXCITABLE MEDIA CONTAINING ACTIVE PARAMAGNETIC CENTERS
D. N. Makovetskii
66-81
The paper is devoted to computer investigations of self-organized autowave motions in bounded nonequilibrium systems of the excitable type including, in particular, phasers with paramagnetic active centers (ACs). A feature of microscopic interaction between such ACs is the presence of not only local activation, but local inhibition of excitations (LIE), which influences essentially the mechanism of the self-organization of autowaves. The main attention is devoted to studying of the rotating spiral autowaves (RSAs) taking into account the LIE channels. It was shown that in a system with LIE the reverberator RSAs (containing dynamic cores) are dominating, and they depress the Wiener RSAs (containing dynamic cores). The phenomenon of the regeneration of reverberator RSA, which manifests itself in a form of a nonlinear «reflection» of RSA from the absorbing boundary of a medium, was revealed. The conditions at which the regeneration of RSA is accompanied by the self-induced inversion of the RCA's topological charge are found. The sliding mode of a RSA's core along the boundary of an active medium was observed for the first time. The mechanisms of these phenomena caused by the role of LIE in processes of the self-organization of RSAs are discussed.
WIDEBAND QUASIOPTICAL SPATIAL MULTIPLEXERS AND DEMULTIPLEXERS OF ELECTROMAGNETIC WAVES FREQUENCY BAND
V. I. Bezborodov, V. K. Kiseliov, Ye. M. Kuleshov, V. K. Laptiy, P. K. Nesterov, I. V. Scherbatko, M. S. Yanovskiy
82-86
Wideband quasioptical spatial multiplexers and demultiplexers were developed and tested for GHz and THz bands. These elements are based on dielectric splitting plates and metal strips grates, placed in diagonal planes of orthogonal branches in square metal-dielectric waveguides. Optimization of such devices have been done as well.
THE MEASUREMENT POSSIBILITY OF LOW SIDE HYBRID MODES IN THE THZ MULTIMODE WAVEGUIDE
A. I. Goroshko, V. K. Kiseliov, S. V. Mizrakhy
87-91
The electromagnetic patterns for radiation from open end of hollow dielectric waveguide in the self mode spectrum are presented. The hybrid side modes are arised by waveguide inhomogeneities and when the HE11 mode is excitated. This level can be determined without phase measurements and frequency tuning by the amplitude measuring of the field radiation from waveguide. The analysis is applicable for dielectric-lined and corrugated waveguides.
ABSORPTION OF OPTICAL RADIATION BY THIN METAL WIRES WITH A POWERFUL PULSE HEATING
A. O. Pak, H. G. Kokodiy
92-95
The results of measurements of the radiation absorption by bolometers that are heated by pulsed radiation are presented. During the pulse the temperature changes from room up to values of several hundred degrees. The temperature dependence on the dichroism coefficient, the absorption efficiency factor Qabs(T) and its absolute value at different temperatures are determined.
PLANAR STRUCTURES OF WAVEGUIDING CIRCUITRY FOR MILLIMETER BAND
S. L. Skripka, V. V. Danilov, I. S. Pavlovsky
96-102
The wave processes in opened planar waveguide were investigated numerically and experimentally. Propagation modes phase velocity measurements methodology and technique were proposed and implemented. According to results of experiment and numerical modelling the planar waveguide is characterized by low loss, low dispersion for quasi-TEM-mode and large scale of integration, and therefore it is perspective for development of short waveguiding structures and integrated circuits for millimeter band. Possibility of development of filters and modulator for millimeter band was also demonstrated in this paper.