back 2001-2-3

 

2001, volume 6, 1

 

 

 

STATIONARY MAGNETIC FIELD OF FRACTAL DISTRIBUTION OF CONDUCTION CURRENTS

V. M. Onufriyenko

7-11

The problem of determination of the stationary magnetic field of fractal current for a geometrical fractal set overlapping has been formulated and solved. The integro-differential measure relevant to current distribution on a geometrical conductor has been estimated. The Biot-Savart-Laplace type formula for a fractal model of the conductor has been derived. The convergence integrals depending on the current quantity, wave resistance, conductor radius and scaling index have been obtained for calculation of the potential and power of a fractal model of a single-wire line. The results of calculation of the stationary magnetic field on a fractal model are completely adequate to the experimental results.

 

 

QUASI-OPTICAL WAVEGUIDE MODELING METHOD FOR THE MEASUREMENTS OF THE SCATTERING MATRIX ELEMENTS IN THE NEAR MILLIMETER AND SUB-MILLIMETER WAVE RANGES

V. K. Kiselyov, A. V. Kiselyov, B. A. Klimko, T. M. Kushta, and P. K. Nesterov

12-21

The possibility of using the quasi-optical waveguide modeling (QWM) method for the study of polarization characteristics of the backward scattering from physical objects or their scaled models in the laboratory conditions in the near millimeter and sub-millimeter ranges of the electromagnetic spectrum is experimentally grounded in the paper. The quasi-optical polarimetric micro-compact range (PMCR) based on a circular hollow dielectric waveguide (HDW), quasi-optical and waveguide devices and components has been developed for implementation of the QWM method. The results of the measurements of the relative scattering matrix (RSM) elements and RSM patterns in the backward scattering have been obtained for a standard object a square cross-section metal cylinder. The PMCR measurements used various linear polarization bases in the 4-mm wavelength range. The comparison of the experimental RSM diagrams of the standard cylinder and theoretical data obtained by means of the geometric diffraction theory has been made. They showed a good agreement and demonstrated the potentialities of the QWM method for modeling the polarization characteristics of the scattering in the near millimeter and sub-millimeter wave ranges.

 

 

MODELING OF RADIATION OF COAXIAL CIRCULAR WAVEGUIDE PULSE TEM-WAVES

A. I. Vyazmitinova, V. I. Pazynin, and Yu. K. Sirenko

22-29

A rigorous solution of the initial boundary value problem has been obtained. The problem describes the transient processes that are an accompaniment of a pulse excitation of an axial-symmetric coaxial-waveguide antenna with a flange.

Exact "absorbing" conditions on the virtual boundaries that close the calculation space in the open-end (infinite) range of analysis have been stated in a correct way and introduced into the finite difference calculation scheme. This has enabled us to build up a highly effective calculation algorithm with the predicted accuracy of calculation of physical quantities.

The result obtained can find application in the effective study of electromagnetic characteristics of both pulse antennae, and antennae operating within the continuous regime for an arbitrary given space domain.

 

 

INFLUENCE OF FINITE CONDUCTIVITY OF END WALLS ON SPECTRAL AND POWER CHARACTERISTICS OF ANISOTROPIC DIELECTRIC DISK RESONATOR

Yu. V. Prokopenko, Yu. F. Filipov

30-34

The high-Q oscillations of a longitudinal-anisotropic dielectric resonator with the imperfectly conducting end walls are considered. Using the integral equation derived by the authors, the spectral characteristics of such oscillations are studied. A cylindrical anisotropic dielectric resonator with the end walls made from a high-temperature superconductor monocrystal is investigated.

 

 

SINGLE RESONANCE FOR DIFFRACTION ON IMPEDANCE GRATINGS

N. A. Balakhonova, A. V. Kats

35-45

The paper presents a detailed analytical and numerical analysis of the resonance diffraction of a plane electromagnetic wave on gratings formed by modulation of the optical properties of a plane boundary of a high reflecting medium. The examination is performed under impedance approximation. Both Wood and Rayleigh type anomalies in the phase and intensity of diffracted waves are investigated under conditions of the single resonance case. In particular, there are analyzed conditions of the maximum transformation of the incident wave into the surface electromagnetic wave and the conditions of suppression of the specular reflection, including the total suppression. The dependencies of the width, location and other parameters of the resonance transformation on the optic characteristics of the media and the grating parameters are obtained. The results show that using of Wood and Rayleigh anomalies is promising in the measurement problems, allowing one to define both parameters of the radiation and the grating, and optical parameters of the medium with high accuracy.

 

 

RESISTANCES OF RADIATION OF ARC-SHAPED WIRE ANTENNAS LOCATED NEAR THE PERFECTLY CONDUCTING SPHERE

Yu. M. Penkin, R. I. Klimovich

46-50

Radiation resistance of thin-arc wire antennas located near a spherical scatterer have been obtained by using the Green's function of electric type for the space exterior to a perfectly conducting sphere. Here, the currents along the electrically short (of order of half the working wavelength) wire antennas have been approximated by the sinusoidal function. The values of self-resistances and coupling resistances of arc-shaped wire antennas have been obtained under variation of geometric parameters of radiation systems containing resonant-size spheres.

 

 

THE TIME-SPATIAL STRUCTURE OF MICROWAVE RADIO FIELDS ON LINE-OF-SIGHT OVERWATER PATHS

A. S. Bryukhovetsky, G. G. Maikov, V. A. Kabanov, V. B. Sinitsky, I. S. Turgenev, S. I. Khomenko

51-60

The result of experimental and theoretical investigations of the time-spatial field pattern on the overwater paths are discussed for radio wave ranges 35,4 and 0,8 cm. Measured height profiles of the field strength within layers up to 23 m (pathlength 8 km) or 92 m (pathlength 21 km) showed distortions in the field lobe pattern due to refraction in the near-water atmospheric layer. As has been found, the distribution of the effective gradient as obtained from the radio physical experiments during the summer and autumn periods, is close to the normal law, with the median value corresponding to the enhanced refraction.

 

 

STUDY OF ALTITUDE AND FREQUENCY DEPENDENCES OF THE LEVELS OF CM AND MM WAVELENGTH RANGE SIGNALS AS THEY PROPAGATE OVER THE SEA SURFACE

V. A. Kortunov, V. N. Gorobets, F. V. Kivva, V. A. Kabanov, I. S. Turgenev

61-66

The results of measurements of the cm and mm signal levels are presented. It is shown that the elevation profiles of the signal levels are characterized by their variety, which is due to different antenna's elevations above the sea level. Thus, in this paper we use the differential characteristics for study of the altitude dependence.

 

 

DIAGNOSIS AND PREDICTION OF THE OPERATION RANGE OF A 3 CENTIMETER WAVE BAND MARINE NAVIGATION RADAR

I. M. Mytsenko, A. N. Roenko, S. I. Khomenko

67-70

An empirical relationship of the tropospheric overwater waveguide height and direct field signal attenuation factor is established in 3 centimeter wave band at different distances. Marine navigation radar operation range diagnosis and prediction technique is proposed. Its applications are determined. The results of the detection range prediction are compared with the original experimental data obtained in various regions of the World Ocean.

 

 

ESTIMATES OF THE LEVEL OF THE GLOBAL LIGHTNING ACTIVITY OBTAINED FROM THE SCHUMANN RESONANCE MONITORING

A. P. Nickolaenko, A. V. Shvets, and E. I. Yatsevich

71-77

Schumann resonance measurements have been performed at the station Lekhta during a year (since August 1999 till July 2000). The data of observation obtained monthly allowed the average field dynamic spectra to be built and the spectrum variation based on the theory of the global lightning activity to be analyzed. The integrated estimations of daily changes of a level of global thunderstorms and the data related to seasonal changes of activity in the world thunderstorm centers are obtained.

 

 

RECONSTRUCTION OF SPATIAL STRUCTURE OF THUNDERSTORM ACTIVITY BY RESULTS OF VLF ATMOSPHERICS DIRECTION FINDING FROM BOARD OF MOVING VESSEL

A. V. Shvets

78-83

A technique of tomographic reconstruction of the spatial structure of lightning activity is proposed. The technique is based on measurement of azimuth distributions of atmospherics from different distant receiving stations. An effective algorithm for tomographic reconstruction has been developed to reduce required computational resources. The spatial structure of thunderstorms in Africa has been estimated from results of direction finding of VLF atmospherics performed from board the scientific vessel during March-April, 1991. The results of reconstruction show that stable active areas correspond to the Niger and Congo basins, Madagascar, and coastal part of the Guinea bay.

 

 

MODELING OF THE INFLUENCE OF SALINITY OF WET SOILS ON THEIR REMOTE SENSING CHARACTERISTICS IN L- AND P- WAVELENGTH RANGES

Y. V. Gorishnya

84-92

The results of numerical experiments on modeling the influence of salinity of wet soils on their radar sensing characteristics in L (20 cm) and P (70 cm) wavelength ranges have been presented. It is shown that a probable reason for imperfect detection of saline soils at the remote sensing in L-band may result from a vertical profile of the soil humidity distribution. The computational results of the error in determination of the soil humidity using the remote sensing in L- and P-bands are given. This error is due to the effect of soil salinity in various geographical areas.

 

 

STUDY OF POLYMODAL DISTRIBUTIONS OF AMPLITUDES BY TH SIMULATION METHOD

Yu. V. Mitikhin

93-96

New algorithms of simulation of fluctuations of amplitudes with the non-uniform statistic distribution of a random field component phase have been developed on the basis of a probability vector model of an ionospheric signal as a sum of regular and random components of EM field. By using the computer modeling method, one can obtain the signals whose distribution density is of the form of the polymodal distribution function. This is in a good agreement with the experimental results dealing with ionospheric probing.

 

 

ON TRANSITION RADIATION OF SURFACE POLARITONS BY A MODULATED FLOW OF CHARGED PARTICLES

V. M. Yakovenko, I. V. Yakovenko

97-102

A mechanism of the interaction of a modulated flow of the charged particles with the surface waves in plasmalike media, superconductors and ideally conducting conductors with a periodically rough boundary have been investigated. Modulation frequency is given by the surface wave frequency. It is found that the density of the energy flow of the surface wave undergoes oscillations depending on the relations between the period of Langmuir oscillations of the electron beam and the time of the particle transit from the modulation plane to the media interface. It is shown that the flow amount can considerably exceed that one for the surface waves excited by a charged strip.

 

 

NONLINEAR SURFACE POLARITONS IN A TWO-DIMENSIONAL ELECTRON SYSTEM PLACED INTO THE QUANTIZING MAGNETIC FIELD

N. N. Beletskii, Y. V. Bludov

103-109

The paper deals with the theoretical investigation of nonlinear surface polaritons (NSP) in an isolated two-dimensional electron system (2DES) arranged at the interface between linear and nonlinear media and placed into the external quantizing magnetic field directed perpendicularly to 2DES. We assumed that the nonlinear medium dielectric permittivity depended upon the tangential component of electric field only. It is shown that under the integer quantum Hall effect conditions all NSP characteristics are represented by the quantized values. It is found that NSP spectrum contains two NSP modes - high-frequency and low-frequency ones. It is shown that NSP can exist only in the case when the value of the electric field tangential component at the interface is less than certain critical value. It is found that the resonant interaction between the NSP high-frequency mode and surface polariton mode occurs in the vicinity of cyclotron resonance subharmonic.

 

 

MICROWAVE REFLECTIVITY OF HTS FILM - DIELECTRIC SUBSTRATE STRUCTURE AT THE ARBITRARY INCIDENCE ANGLES

A. I. Gubin, A. A. Lavrinovich, N. T. Cherpak

110-116

Microwave reflectivity of HTS film - dielectric substrate structure in the framework of "optical" terminology has been studied by means of the computer modeling. An enhanced two-fluid model of HTS microwave properties is applied. Some features peculiar to the behavior of the reflection coefficient of a p-polarized wave being arbitrary incident on a sample are observed, and the difference between the values of reflectivity in S- and N-states is calculated. For the thin HTS films (thickness < ), the non-monotonic dependences of the reflectivity on both the temperature and angle of incidence (in N-state) are observed. For the thick films (thickness > ), the difference enhancement factor can be as much as 25 at the incidence angle of . To perform the simulation, the material parameters of YBa2Cu3superconductor and LaAlO3 substrate in the frequency range of 40-160 GHz have been used.

 

 

ANOMALOUS TRANSPARENCY OF A THIN METAL FILM CARRYING A STRONG TRANSPORT CURRENT

S. A. Derevyanko, O. I. Lyubimov, V. A. Yampol'skiy

117-123

A new phenomenon of anomalous penetration of an electromagnetic wave into a thin metal plate with a strong DC current is predicted. We show that the AC field of the wave can be driven to the opposite side of the sample even if the spatial dispersion is strong and the penetration depth is much less than the sample thickness. The effect is due to the group of electrons entrapped by the self magnetic field of the transport current. We also predict the cyclotron resonance for the trapped electrons, which is due to the periodical returns of the latter to the skin layer.

 

 

NONLINEAR DYNAMICS OF THE PHONON STIMULATED EMISSION IN MICROWAVE SOLID-STATE RESONATOR OF THE NONAUTONOMOUS PHASER GENERATOR

D. N. Makovetskii

124-134

The microwave phonon stimulated emission (SE) has been investigated in a solid-state resonator of a non-autonomous acoustic quantum generator (phaser). Branching and long-time refractority (absence of the reaction on the external pulses) for deterministic chaotic and regular processes of SE were observed in the experiments with weak and strong electromagnetic pumping. The pronounced increase of the number of the independently co-existing SE states as the pumping level rise has been observed both in physical and computer experiments. This confirms the analytical estimations of the branching density in the phase space. The nature of the SE pulses refractority is closely connected with such branching and reflects the crises of strange attractors, i.e. their collisions with unstable periodic components of the higher branches.

 

 

In0,4Ga0,6AS GUNN DIODES WITH m-n:InP1-xAsx BY THE CATHODE

Yu. V. Arkusha, E. D. Prokhorov, I. P. Storozhenko

135-139

On the basis of a two-temperature model the operation of In0,4Ga0,6As Gunn diodes with m-n:InP1-xAsx by the cathode on the basic harmonic is investigated. Here, the temperature of a crystal lattice is 300 K and the length of an active region 0.5, 0.8, 1.0 m. The influence of a heterocathode on the appearance of a current instability in the diode is considered. Power and frequency characteristics are obtained. For each diode length the optimal InP1-xAsx structure is determined . For the diode with the length of the active region 1.0 m, the optimal height of a potential barrier on the metal-semiconductor contact is also determined. It is shown that the greatest diode generation frequency is ~250 GHz.

 

 

APPROXIMATE ANALYTICAL NONLINEAR THEORY OF THE ORMOTRON

G. A. Alexeev

140-143

The analysis of the steady - state mode of the M-type generator with an injected electron beam and an open resonator - ormotron - is carried out within the framework of the approximate analytical non-linear theory. The method is based on using the quasilinear and asymptotic expansions for evaluation of the interaction integral. It is shown that the ormotron can be a highly effective coherent microwave source having both the high efficiency and high stability of oscillations. It is shown that the ormotron is a generator with hard self-excitation.

 

 

ON THE INTERACTION BETWEEN AN ELECTRON BEAM AND A SLOW ELECTROMAGNETIC WAVE IN AN O-TYPE OSCILLATOR

Yu. V. Kornienko

144-149

The electron motion equation in the longitudinal electric field of a slow wave with a constant amplitude is considered, and its approximate solution in the form of power series in the small wave amplitude is analysed. It is shown that the mode of the most effective energy transfer from the electrons to the wave is always beyond the limits of the approximation applicability. So, this approximation cannot be used to describe an oscillator when its efficiency coefficient is close to the maximum possible value.

 

 

DIELECTRIC PERMITTIVITY OF DISORDERED DISPERSE SYSTEMS WITH THE ARTICLES OF VARIOUS SHAPES AND STRUCTURES

S. V. Gatash, L. D. Styopin

150-153

A theoretical study of the dielectric permittivity of disperse systems for the cases of various shapes of particles has been performed. An approximation permitting the spread of the theory of the additive contribution of dispersive and disppersion phases to the case of a big volumetric fraction of the impurities has been considerated. The equation describing the dielectric permittivity of particles with disordered structure has been presented. The developed theoretical aspects and experimental data have been used to determine the dielectric permittivity of erythrocyte's inside medium and estimate the amount of bound and free water inside the cell.

 

 

ANALYSIS OF NEAR FIELDS OF THE A THREE-DIPOLE IRRADIATOR IN A DISSIPATIVE MEDIUM

G. A. Alexeev, M. V. Belobrova

154-164

A comparative analysis of the near electrical field generated by a three-dipole irradiator in a relatively dense dissipative dielectric medium such as fat or muscle tissues is performed. The irradiator is formed by uninsulated or insulated symmetrical dipoles and may be used in RF and microwave interstitial hyperthermia. It is shown that the application of the three dipole irradiators may widen an area of comparatively uniform heating. It is shown that the microwave irradiator with a quadrature feed, when one dipole is an active reflector, has a high directionality in a dense dissipative medium.

 

 

SLIDING NEIGHBORHOOD FILTERS FOR GROUND PENETRATING RADAR IMAGES

V. O. Kovalenko

165-171

The use of sliding neighborhood filters in the processing of video pulse ground penetrating radar images is described in this paper. The filters for the local object image focusing and stratified soil imaging are fabricated. Also a set of empirical rules for the practical use of these filters in real-world applications is presented.

 

 

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