Radio physics and electronics

4-9

Authors: I. M. Mytsenko, D. D. Khalameyda

At present, the overload problem of pulsed radar receivers of signals reflected from targets is particularly relevant, which is caused by the appearance of new types of radio engineering systems for various purposes. To protect amplifiers against overload, a number of methods are used: automatic gain control (AGC) depending on the level of the input signal, separation of the dynamic range into parts and multichannel amplification, the usage of amplifiers with a logarithmic amplitude characteristic, etc. Good results are obtained by a combination of logarithmic gain and signal AGC. The paper describes a pulsed logarithmic amplifier with inertial automatic adjustment of the signal gain factor, operating in the frequency range from 1 MHz to 8 GHz. The functional and the principal electrical circuits are shown. A small-scale experimental model of the device was developed using a modern element base which greatly expanded the possibilities of its application. The physical basis for selecting the necessary bandwidth, which allows avoiding the distortion of radio pulses spectra and the dynamic mode of operation of the inertial AGC, is considered. Experimentally obtained amplitude characteristics are given. The parameters of the layout are as follows: the gain factor K0 in the linear section ~53 dB; the dynamic range of input signals ~55 dB; input and output resistance Rin » Rout = 50 Ohm; supply voltage ±12 V (consumption current of 100 mA), ±5 V (consumption current of 20 mA)

19-33

Authors: I. G. Kudintseva, Yu. P. Galyuk, A. P. Nikolaenko, M. Hayakawa

The investigation of the effect of space weather on different layers of the terrestrial atmosphere has been and remains a relevant problem of remote sensing of the environment. We describe a technique for detecting modifications of the peak frequencies of the Schumann resonance during the sudden ionospheric disturbances (SID) caused by the solar X-ray flares. The SID is associated with a sharp lowering of the ionosphere over sunlit hemisphere during the chromospheric flare. Lowering of the daytime ionosphere reduces the average height of Earth-ionosphere cavity and leads to an increase in Schumann resonance frequencies. The model of the conductivity profile of the middle atmosphere and its modification is used. The resonance frequencies of the Earth-ionosphere cavity and the characteristic heights of the conductivity profile are calculated by the full wave method for the ionospheric disturbances of different intensity. The power spectra of the vertical electric field are computed using the 2D telegraph equations for the uniform spatial distribution of thunderstorms in the resonator with the day-night non-uniformity at several positions of the observer relative to the solar terminator. The changes in the peak frequencies are obtained depending on the intensity of the ionospheric disturbance. The weighted average frequency of the Schumann resonance is calculated for the first three modes, and, using the least squares method, the parameters of linear dependence of this frequency on the intensity of the SID and/or on the changes of magnetic characteristic height of the conductivity profile are established. The data are suggested to be used as a calibration curve for interpretation of the observational results and estimation of the modification in the lower ionosphere from the Schumann resonance frequencies

42-52

Authors: L. F. Kupchenko, A. S. Rybiak, O. O. Goorin

The article is devoted to the study of the properties of the electro-optical systems with matched spectral dynamic filtration. It is usually supposed that the optimal optical signal detector is synthesized under the assumption of a priori information about the statistical characteristics of the target and background signals and the equality of the target and the background correlation matrices. However, in practice, there is always a mismatch between the input and the reference (expected) optical signals. The purpose of this article is to generalize and develop the methods for estimation of matching of the optimal signal processing in electro-optical systems with dynamic spectral filtration, which makes it possible to study the effect of the difference between the input and reference signals on the processing quality. In this paper, the information criterion – the normalized Kullbak–Leibler divergence, which is the ratio of the divergences at the output and input of the dynamic spectral filter – is used as a measure of matching of the optimal signal processing in electro-optical systems with dynamic spectral filtration. The analysis of the properties of the suggested information matching indicator and its comparison with the probability of correct detection is carried out. A mathematical model of the process of optimal dynamic spectral filtration in electro-optical systems is constructed. The examples show the extent to which the differences in the statistical characteristics of input and reference signals affect the information matching indicator. In particular, the article poses and solves three problems that illustrate the process of optimal spectral filtration in the following situations: 1) the statistical properties of the input and the reference signals coincide completely; 2) the mean brightness of the optical radiation of the target and the background at the input of the electro-optical system has changed; 3) the statistical characteristics of the background input signal differ from the reference values.

61-70

Authors: А. О. Puzanov

The relevance of the study presented is caused by the possibility to use a torch discharge (TD) in many useful applications along with a substantial lag in its practice-oriented theoretical studies. In this paper, the proposed by the author original method for measuring the resistance of the TD (Rd) taking into account the discharge inductance L is considered. The formula for calculation of Rd from the data measured at two frequencies is proposed. The data measured are the values of the function a, namely the ratio of voltages at which the electrical and geometrical characteristics of the torch discharge remain unchanged. In particular, an inequality for estimation of definition area of a, when the formula for Rd is used, is found. It is established that the frequency dependency of a has a minimum at the resonant frequency of the discharge circuit wr. At L ® 0 the minimum becomes an asymptote for a similar dependency of a at L º 0. It is shown that the minimum of a is always located above the indicated asymptote at the ordinate axis if the influence of L has to be accounted. It is concluded that the measured value of a has to correlate with the accuracy of the measuring equipment including devices for controlling the constancy of geometrical parameters of the torch discharge excited at two frequencies. Therefore, the measured value of a has to be as less as possible. It can be achieved if the frequencies of excitation are significantly different. The approach proposed results in more effective using of industrial resources.

82-88

Authors: N. N. Chernyshov, A. U. Panchenko, V. M. Pisarenko, M. A. F. Alkhawaldeh, K. T. Umyarov

In the present paper, the analysis of structures of modern photoelectric solar energy converters is carried out. The solution of ecological problems at increasing energy consumption and limitations of traditional earthly resources makes the tasks of using alternative and renewable energy sources actual. The sun is a practically unlimited energy source for earthly applications. Development of effective structures and designs of photoelectric converters provides the access to this source. Currently, their practical application is limited due to the high cost of solar batteries. The paper generalizes the known results of solving the problems of creating photoelectric converters. The design and operation principles of photoelectric converters are shown, single- and 3-stage elements are considered. Conditions for efficient operation of photoelectric converters are determined. Particular attention is paid to materials for creating elements of photoelectric converters. The paper considers the peculiarities of materials in which potential barriers are formed and pairs of electrons and holes are generated. In addition, the paper deals with the materials that are used for forming the constructions of photoelectric converters, namely, the materials of plates, contacts etc. These materials must provide a considerable barrier height in a semiconductor junction. The generated electrons and holes are effectively collected at contact electrodes. The considered conditions of efficient operation of photoelectric converters determine their practical importance. It is shown that the further increase of efficiency of photoelectric converters requires the development of technologies, improvement of structures, and application of physical principles that are not used yet, as well as new combinations of those that are already being used.

3-10

Authors: A.V.Hnatovskyi, S.A.Provalov

The development and improvement of operational characteristics of communication lines, radiolocation, navigation, surface overview, remote control and warning systems at the airports and at the stations is provided by the development of shorter-wave ranges. Designing new millimeter and submillimeter waveband radio complexes requires not only the modernization of existing antennas but also the creation of new antennas classes. Diffraction radiation antennas, for example. One of the basic problems in antenna engineering is the formation of required amplitude-phase distribution (APD) of electromagnetic field on antenna aperture that provides the given operational characteristics. The known techniques of APD forming at the aperture of diffraction radiation antennas are acceptable for aperture not less than 50 wavelengths. In this paper the possibility of forming the amplitude distribution with symmetrically falling edges at the 10...50 wavelength aperture by adding an additional segment of dielectric waveguide is investigated. The additional segment of dielectric waveguide changes the sequential system of radiating elements feeding into a sequential-parallel one. The efficiency of energy and APD transformation for different values of dielectric waveguide – dielectric waveguide and dielectric waveguide – grating coupling factor is evaluated. The results can be applied in the design of millimeter antenna systems and functional unit based on open transmission lines.

19-30

Authors: V. V. Ovsyanikov

The current methods and devices for correcting and controlling the directivity patterns of metal whip and loop reconfigurable antennas, as well as plasma and electron beam reconfigurable antennas are investigated. It is proposed to solve the problem of effective correction and control of antenna directivity patterns by changing their design and incorporating concentrated reactive loads and switches into the shoulders of antennas. Similar problems are proposed to be solved by the creation of reconfigurable antennas based on cold plasma or streams of moving electrons with switched on information signal and power switches. The results of calculations of Z-shaped and rhombic antennas with controlled radiation patterns with lumped loads and switches included in radiating conductors are presented. The results of studies of the gain factor and the standing wave coefficient with respect to the voltage of the antennas with corrected and controlled radiation patterns are presented. It is noted that unlike metallic reconfigurable antennas and antenna arrays in plasma and electron-beam antennas, there are more opportunities to control radiation patterns and other electrical parameters by creating so-called "conducting paths" in them. In this case, the disconnected conductive paths no longer affect the operation of the antenna. In reconfigurable plasma and electron-beam antennas, it is proposed to plan and program in advance the activation and deactivation of the necessary "conducting paths" at given time periods in order to obtain the required directional patterns. The results of the calculation of directional patterns and other electrical parameters of a metallic collinear antenna array of the Franklin–Marconi type and a plasma eight-element reconfigurable antenna are presented. A variant of a new electron-beam reconfigurable antenna is presented. The results of the research are given in the form of a table and graphs. It is noted that metal, plasma and electron-beam reconfigurable antennas are promising for use in radio engineering systems, including terrestrial, marine and aerospace telecommunications and radiolocation systems.

39-48

Authors: L. F. Kupchenko, A.S. Rybiak, O.O. Goorin

This paper generalizes and develops the principles of dynamic spectral filtration, which is a further development of imaging spectroscopy. Electro-optical systems with dynamic spectral filtration in contrast to imaging spectrometers realize controlled spectral filtration, which ensures maximum suppression of the spectral components of background radiation with a minimum attenuation of the target optical signal in the pre-detector area. The purpose of the article is to generalize and develop the principles of dynamic spectral filtration in the interests of creating electro-optical systems of targets detection by spectral features. The problem of optimal selection of optical signals from background noise has been reduced to solving a problem of signal detection with a priori known parameters used in radiolocation theory. The article states the principles of dynamic spectral filtration of optical radiation. It also describes an algorithm for optimal detection of targets by spectral characteristics and carries out a synthesis of an optimal optical signal detector. The paper defines the quantitative characteristics of the detector, that for a given false alarm level allows to determine the conditional probability of correct detection of the targets of observation depending on the signal-to-interference ratio. The quantitative characteristics of the detector were obtained on the assumption that the signals of the target and the background obey the normal distribution law, and their correlation characteristics (the correlation matrices of the background and the target) are equal. The work experimentally establishes the possibility of creating a controlled acoustooptic selection device providing a spectral selection of two optical signals differing in spectral composition by varying the amplitude of the frequency components of an ultrasonic wave. In this case, three lasers operating in the red, green and blue regions of the spectrum were used as the source of optical radiation. In the course of the experiment, spectral selection was provided by diffraction of polychromatic laser radiation by multifrequency ultrasound. The efficiency of the filtration process was determined by the contrast value before and after filtration. It was experimentally established that, in the presence of three spectral channels of selection, it is possible to increase the contrast at the output in several times.

55-61

Authors: A.V. Lysenko, G.A. Oleksiienko, A.V. Pavlov

The research subject is the amplification characteristics of the plasma-beam superheterodyne free-electron laser of the dopplertron type. The purpose is to theoretically investigate the influence of longitudinal magnetic field on the wave amplification in such a device in order to find the optimal operation mode. As initial we use the quasihydrodynamic equation, the continuity equation and Maxwell’s equations. The motion problem is solved by means of the modernized method of averaged characteristics. The problem of electromagnetic self-fields excitation is solved through the slowly varying amplitudes method. We have analyzed the influence of the axial guiding magnetic field on the waves dynamics in a plasma-beam superheterodyne free electron laser with Dopplertron pump in the framework of the cubic nonlinear approximation. We found out that the intensity of electromagnetic radiation increases, when the intensity of the axial guiding magnetic field decreases right up to a critical value. We found the critical value of magnetic field strength, and the saturation levels of electromagnetic waves. We have demonstrated that the investigated free electron laser can be used as a powerful amplifier of electromagnetic radiation in the millimeter wavelength range.

69-73

Authors: S.V. Nedukh, S. Y. Polevoy, S. I. Tarapov, A. S. Vakula

At present, the fast contactless identification of liquids enclosed into a container has a practical importance. The identification of liquids can be required, for example, at airports, in order to prevent the transport of illicit liquids in bottles. However, the complexity of applying contactless methods lies in the difficulties to take into account the influence of container characteristics. In this paper, a metamaterial based on two planar photonic crystals (PPC) has been applied for the experimental analysis of liquids in different containers. It was shown experimentally how the transmission coefficient spectrum of PPC varied with changing the characteristics of a container with a liquid. Namely, the influence of thickness and material of the container walls and the inclination angle of its axis relative to the metamaterial plane on the transmission coefficient has been studied. The reliable differing of concentration increments of edible salt and sugar in water was determined as 10 %. It is shown that an increase of the container walls thickness leads to a decrease of the reliability of the liquid identification in it. Thus, the influence of some container characteristics on the reliability of contactless identification of liquids by using PPC has been taken into account.

78-81

Authors: N.V. Bryuzginova, S.P. Sirenko, A.I. Fisun, O.I. Belous

An electrophoretic mobility of the cell kernels is one of the physiological factors of a human organism state. Therefore, investigation of change in that parameter under the influence of the external factors (in this context a microwave field) is a currently central problem. In this paper the results of electrokinetic factors study of buccal epithelium cells are presented. Patients with a discirculatory encephalopathy and acute disorder of the cerebral circulation have been studied. The main method of investigation was the method of intracellular microelectrophoresis of cell nuclei. The studied parameter, electrophoretic mobility of the cell nuclei (EMN, %) index, represents the number of negatively charged nuclei in the sample of cells. It has been found that the action by the wavelength l = 7.1 mm (one of the biologically active wavelength) has culminated in the change in electrophoretic mobility of cell nuclei index. These changes depend on the level of disease and thus, on the organism reaction to an external irritation. The investigated results may be useful in medical application for disease difficulty determination and pharmacological treatment selection.

3-7

Authors: A. V. Gribovsky

In connection with the urgency of creating new metamaterials, multilayer interference structures are recently of great interest. The quasiperiodic sequence of Fabry–Perot resonators based on plane screens of finite thickness with rectangular holes are investigated. It is shown that the finite sequence of Fabry–Perot resonators of flat screens of finite thickness with rectangular holes in the frequency region below the cutoff frequency of rectangular waveguides has the ability to localize electromagnetic energy in the regions of the resonators. The amplitude of the field in resonators at resonant frequencies can exceed the amplitude of the plane wave exciting the structure under investigation by almost an order of magnitude. It is established that an increase in the number of resonators leads to an increase in the number of the total passage resonances of a plane wave through a system of resonators. This structure behaves like an electromagnetic crystal that has zones of «blocking» and zones of «transmission» of electromagnetic waves at frequencies much higher than the cutoff frequency of rectangular waveguides.

14-22

Authors: A. V. Shvets, A. P. Kryvonos

At present, the lower ionosphere is the least studied region of the ionosphere. The altitude range and the low concentration of charged particles limit the possibilities of its investigation using radiosondes, balloons, rockets, and satellites. For studies of the lower ionosphere, tweek-atmospherics (tweeks) – ELF–VLF radio waves excited by lightning discharges in the Earth-ionosphere waveguide are used in this work. The authors proposed a method of automatic identification and analysis of tweeks. On the basis of analysis of tweeks recorded in August 2014, the relationship between the regular variations in the height of the ionosphere with the change in the solar zenith angle, which determines the main source of ionization - the radiation of the geocorona at night, was investigated. It is shown that with an increase in the height of the lower boundary of the ionosphere, the rate of tweeks increases, which is associated with a decrease in losses in the ionosphere. The effect of the rise of the lower boundary of the ionosphere during a geomagnetic storm of moderate intensity was detected. Thus, the diagnostic capabilities of the proposed method are demonstrated, which makes it possible to locate thunderstorm foci and to reveal variations in the height of the Earth-ionosphere waveguide along the propagation paths of VLF radio waves excited by lightning discharges from different foci.

33-36

Authors: A.L. Nikytenko, V.I. Kostenko, V.I. Grygoruk, V.F. Romaniuk

In this work we study the properties of hysteresis of ferro-magnetic resonance frequency-field dependence in the samples of barium hexaferrite. The purpose of the study is the experimental investigation into the properties of high-frequency magnetic hysteresis within the wide range of the samples thickness. The experimental investigation was carried out using EHF-spectroscopy technique. The field method is used to obtain a cylindrical domain structure. It was found that in thick samples (t > 100 μm) the transition to a saturated (single-domain) state occurs at lower values of the external magnetic field Hs, moreover, the dependence of this field on the thickness is close to the linear one. Furthermore, a similar dependence is observed for the field Hbr of the sample transition to a multi-domain state. At the same time, there is no strict dependence of the hysteresis value on the change in the thickness of the samples. The shift of the frequency-field dependence of the ferromagnetic resonance in the high-frequency region under the saturated state of thick samples of barium hexaferrite was detected. It was found that each investigated sample can be characterized by some average value of hysteresis different from the others.

47-57

Authors: V. V. Ovsyanikov

The results of a theoretical and experimental study of the distribution of the amplitude of a complex current, input resistances, the standing wave voltage coefficient, and the directional patterns of multifrequency and two-frequency linear microwave wire antennas with quarter-wave coaxial, two-wire shunts and with concentrated reactive loads are presented. As a result of the research, it was found that with a constant size of a quarter-wave shunt attached to the antenna and with different sizes of the antenna relative to the shunt, it can acquire or lose the multifrequency property. Namely, with the length of the wire rod protruding beyond the shunt equal to an odd number of quarters of the short wave of the upper frequency range the multifrequency mode is observed. Otherwise, the multifrequency mode is not respected. The principle of eliminating the drawback noted above and the creation of two-frequency antennas for working with an arbitrary ratio of co-placed frequencies is proposed and tested experimentally. This principle consists in adjusting the electrical length of the wire rod of the antenna that protrudes beyond the shunt by sequentially including a concentrated reactive load in its rupture, the value of which must satisfy two conditions. Namely, the condition for creating the maximum potential difference in the opening of the shunt at the upper operating frequency and the condition for ensuring the mode of successive resonance of the antenna at the lower operating frequency. The results of the research are presented in the form of tables and graphs of current distribution, input resistances, VSWR and directional patterns of similar antennas, as well as the values of inductive loads calculated according to the proposed expression and included in the protruding part of the antenna rod outside the shunt. The proposed method for calculating and optimizing two-frequency antennas for working with an arbitrary ratio of compatible frequencies was experimentally tested. It is noted that the investigated two-frequency antenna with two-wire linear shunts and with included inductive loads, is one of the promising options for the development of small-size dual-frequency antennas and antenna arrays in microstrip performance.

81-85

Authors: N.V. Khmil, V.G. Kolesnikov

In the metal-working industry lubricants are one of the many components which ensure the quality of finished goods. During operation the imbalance of lubricants’ components is being observed by reason of contamination by bacteria, mold fungi and microalgae. These factors result in both low-quality metalworking and allergic diseases of plant personnel. The present methods register these changes not very efficiently and for a long time. On frequencies of dispersion of free water permittivity the microwave dielectrometry makes it possible to estimate structural and functional state of a biological system in real time according to the change of bound and free water quantity on macromolecular complexes. The aim of this work is the determination of efficiency of control of biological contamination of organic and synthetic lubricants via permittivity and surface tension and also structural and functional characteristic of the microflora. In this work we have carried out measurements of permittivity and surface tension of organic and synthetic lubricants (freshly prepared and worked-out) by means of microwave dielectrometry. Biological analysis of the microflora’s morphological particularities has been fulfilled by calculation of bacterial colonies with subsequent determination of cells via a microscope. According to the experimental data the increase of bound water in the system of worked-out lubricant and microflora in comparison with freshly prepared samples was observed. We revealed the decrease of permittivity and surface tension in synthetic worked-out lubricant perhaps by reason of contamination by gram-positive nonspore-forming bacteria. According to the fulfilled measurements the lubricants’ quality control can be a marker for a timely replacement of low-quality lubricants and for a decrease of defective goods.

3-10

Authors: V.L. Pazynin

A rigorous mathematical model of the diffraction of an electromagnetic wave in the bend of a plane-parallel waveguide is constructed. Within numerical simulation of the waveguide bend the effect of its complete locking at a frequency located nearby the critical frequency of the second mode is revealed. The resonant nature of this effect, which consists of excitation of locking oscillation in this waveguide inhomogeneity, is found. The conclusion is that the bend of a waveguide could be considered as an open-type waveguide resonator. The importance of the solved problem is caused by wide waveguide bends applications in the microwave technology.

17-22

Authors: V. G. Sugak

The article presents the results of research on opportunities of revealing a weak target movement in foliage-penetration environment with the use of Stepped Frequency Continuous Wave Radar in the frequency range of 1 200…1 800 MHz. The entropy weighed coherent integration (EWCI) algorithm is adopted to phase fluctuations of radar returns and it allows the multipath effects to be mitigated and the detectability and visibility of targets behind foliage brushes and trees to become significantly better.

28-40

Authors: Yu.P. Galyuk, A.P. Nikolaenko, M. Hayakawa

Accounting for the actual structure of the lower ionosphere in the problems of global electromagnetic (Schumann) resonance is an important and urgent task. The paper analyzes an impact of deviations in the vertical profile of the atmosphere conductivity at the night and the day sides of the planet on the spatial distribution of electromagnetic field in the Schumann resonance band. The cavity characteristics depend on the conductivity profiles and are accounted for at the day and the night sides by using the full wave solution method. The problem in non-uniform cavity is solved with the help of 2D telegraph equation. The shift of the maximum amplitude of the electric field component from the source geometric antipode is demonstrated at several frequencies for different locations of the source, and in the models of smooth and sharp day–night transition. We demonstrate that the day-night non-uniformity is able to shift the antipode maximum of the vertical electric field from the source geometric antipode of the center towards the center of the day hemisphere by a distance reaching 300 km.

50-57

Authors: P. V. Kholod, L. A. Varyanitsa-Roshchupkina, Т. N. Ogurtsova

The causes of afterpulse current oscillations in electrically large loop antennas have been found basing on the analysis of results of simulation of the space-time current distribution induced by electric and magnetic field components in the circular and rectangular loops. It has been determined that the pulse shape distortion is due to the current induced by the electric component of the incident field. For undistorted reception, it is necessary to isolate only the current induced by the magnetic component from the total current. To do this, it is sufficient to sum the currents induced in diametrically opposite sections of the circular loop. It has been found experimentally that undistorted reception can be ensured by summing the signals recorded in diametrically opposite sections of the circular loop.

66-71

Authors: N. N. Beletskii, S. A. Borysenko

The effect of reflectionless normal transit of electromagnetic waves through symmetric three-layered structures containing negative-permittivity layers excites considerable interest. It is stipulated by both an unusual nature of the effect and its unique technical applications. Moreover the electromagnetic-wave reflectionless transit effect has been investigated not enough and not all the peculiarities of the effect have been found and described yet. By now the reflectionless transit effect has been considered only for some concrete values of the permittivity and thickness of a symmetric three-layered structure. In this paper a more general approach based on entering dimentionless values of the thickness of the structure layers is used. This approach makes it possible to study the reflectionless transit effect irrelatively to some concrete wave band. It is shown that the presence of a negative-permittivity layer in a three-layered structure leads to a considerable change in the reflection spectrum of electromagnetic waves. It has been found that in the reflection spectrum of the electromagnetic waves there are wide regions of a weak reflection. The width of these regions can be controlled efficiently by matching a value of the negative permittivity of the middle layer in the three-layered structure. The influence of the energy losses in the middle layer of the three-layered structure on the reflection spectrum of the electromagnetic waves is studied. The obtained results are of great practical importance for developing new devices of electronics, photonics, and photovoltaics.

79-84

Authors: N. G. Kokodiy, A. O. Natarova, V. A. Timanyuk , I. A. Priz

The availability of radio communication, television, radiolocation, remote information processing systems led to the appearance of an intense electromagnetic background in our environment. In many cases, it is the cause of the disturbance of the correct functioning of biological objects, a hindrance to the operation of radioelectronic devices – information transmission systems and military equipment. Therefore, there is a need to protect objects from electromagnetic radiation. Particular attention is given to the development of screens and coatings, the effectiveness of which is achieved through the absorption of electromagnetic radiation, since the reflection of electromagnetic radiation often has a negative effect associated with the formation of a re-reflected wave effecting the screened object. In addition, it can help to identify an object by external sensors in cases where it is undesirable. The effect of an anomalously large absorption of microwave radiation by conducting fibers is observed when electric vector of an electromagnetic wave which falls on a fiber is parallel to the axis of the fiber. The possibility of using this effect to create protective screens is considered in this paper. The study showed that electromagnetic radiation is very strongly absorbed and dissipated by thin conducting fibers if the electric vector of the wave is parallel to the fiber axis: the values of the absorption and scattering efficiency factors can reach several hundred and even thousand, that is, the effective absorption and scattering cross sections can be in several hundred or thousand times higher than the geometric cross sections of the fiber. This is a size effect, the nature of which, perhaps, is related to the effective excitation of currents at certain ratios between the fiber diameter and the wavelength of the radiation. Also in the work, the advantages of graphite fibers in front of metal ones as a material for absorbing screens have been experimentally proved. The results of the study can be used to create protective screens in the microwave range.

3-14

Authors: V. L. Pazynin

The multiplet properties in the frequency dependence of the transmission coefficient of an electromagnetic wave through the chain of coupled waveguide resonators are investigated by means of a numerical experiment. For a small number of resonators the actual problem of determining the structure of standing waves resulting in a chain at resonance wave pass through it has been solved. The restrictions on the usage of standard nomenclature of oscillations in such chains are detected. A new physical treatment of the oscillations in which a standing wave is not excited in particular chain resonators is suggested. These oscillations may be interpreted as the breakup of a long chain of coupled resonators into the sequence of uncoupled shorter ones. The results can be used in the development of waveguide filters, antennas, linear accelerators, slow-wave structures.

21-26

Authors: J. V. Antonenko, A. V. Gribovsky

Mirrors of the Fabry-Perot resonator in the microwave band can be represented by conducting plates with a great number of holes, which ensure partial mirror transmission.It is shown through numerical modeling that the magnitude of the reflection factor of a plane linearly polarized wave from a resonator with coaxial-sector holes in the mirrors is equal to zero for a wave-length which is greater than the cutoff one of the coaxial-sector waveguides. In this case the electromagnetic field amplitude in the resonant cavity shows an increase by an order of magnitude as compared with the exciting field amplitude. It has been found that replacement of one of the mirrors in the Fabry-Perot resonator by a continuous screen can result in increasing the plane wave ampli-tude in the resonator by almost two orders of magnitudewith respect to that of the exciting field.

38-44

Authors: O. V. Sytnik

The adequate models of information signals and noise have been developed to solve the actual problem of the synthesis of hardware and software for operative detection of affected peop-le in man-made or natural disasters. It is shown that at low frequencies, where are placed the spectral components of the information signal generated by breathing and heartbeat, an adequate model of the fluctuation noise is a flicker noise model built on the basis of recurrent equations of Perron-Frobenius operator. The spectral characteristics of the information signal and noise are investigated. The information signal model is built on the theory of periodically correlated random processes and verified on experimental data. A signal processing algorithm has been proposed. The algorithm is based on a process of cross-sampling summing. A criterion to assess the duration of the period of the signal is proposed. The criterion is a function of the signal dispersion from the lattice function period. The ergodic property of the process on an equidistant grid is theoretically proved and experimentally confirmed. The optimal estimate of period duration is an argument of the global maximum of the polymodal criterion function. The simulation results are confirmed by the experimental data.

51-56

Authors: S. Yu. Karelin

In recent years, the high-voltage pulse devices using nonlinear properties of ferrite have received more attention. For the analysis of this kind of objects, the 2D numerical modeling technology of nonlinear saturated ferrites by FDTD method has been developed. Landau–Lifshitz equation, which describes ferrite dynamics, is solved by Runge–Kutte method and unknown components of electromagnetic fields are calculated by using linear interpolation. This method has been used to analyze oscillation forming in coaxial line partially filled with ferrite magnetized by external magnetic field. The numerical results are in agreement with the experimental data

68-76

Authors: Yu. S. Kovshov, S. S. Ponomarenko, S. A. Kishko, S.A.Vlasenko, A. A. Lihachev, V.V.Zavertanniy, E. M. Khutoryan, A. N. Kuleshov

Reliable simulations of electron-vacuum devices’ opera-tion parameters are an actual challenge during the R&D process. One of the most important problems is determining high frequency ohmic losses and taking them into account in the simulation. The surface roughness investigation of the clinotrons’ slow-wave structures, manufactured by electro discharge machining, with the methods of optical microscopy is proposed in this paper. As a result the real values of the surface roughness were considered for the high frequency ohmic losses estimation of the real slow-wave structures. Taking into account the electron beam interception with the slow-wave structure surface, the temperature load simulations have been carried out and the temperature gradient of the clinotrons’ slow-wave structures of 2-mm, 0.75-mm and 0.33-mm wavelength ranges was found. The electric conductivity decrease caused by surface roughness and increase of temperature of a slow-wave structure with beam current has been taken into account at the simulation of the clinotron output power. The qualitative and quantitative agreement between experimental data and simulation results was achieved for the 136 GHz and 301 GHz clinotrons.