Radio physics and electronics

3-15

Authors: O.A. Orlenko, L.A. Varyanytsya-Roshchupkina, G.P. Pochanin, S.O. Masalov, V.G. Korzh

Subject and Purpose. This theoretical and experimental research is devoted to peculiarities of the ultra-wide bandwidth (UWB) pulse radiation from active bow-tie dipoles. The focus is on the relationship between the amplitude-time dependences of electromagnetic fields produced by active UWB pulsed antennas and the configuration of the conductive components for temporally short (less than 0.5 ns), ultra-wide-bandwidth pulse radiation. Methods and Methodology. Analysis of the radiator geometry action on the emitted pulse parameters is performed by numerical simulation with the use of the finite-difference time-domain (FDTD) method. The experiment involves specially made, variously shaped bow-tie radiators tested with different resistive loadings in radiation mode. The numerically simulated characteristic curves of the radiated field amplitude shape versus radiator geometry are confirmed by experiment. Radiation field parameters versus load resistance are experimentally studied, too. Results. Conditions for the effective pulse radiation with a largest-possible pulse amplitude have been determined, the post-pulse oscillation amplitude and duration reduced to a minimum. Conclusion. It has been shown that the resistive loading in the excitation area significantly reduces amplitudes and durations of post-pulse oscillations in signals radiated by active dipole antennas.

22-27

Authors: І.М. Mytsenko, O.M. Roenko

Subject and Purpose. The progress in the development of communication means requires a brand-new radar-component base and state-of-the-art technologies of signal processing. Last years, passive radar systems have become increasingly important. Yet such a shortcoming as poor estimation of the target distance takes place when the signal reception is only provided by a single station. The present work suggests a concept of the object distance determination by passive radar means under far-tropospheric radio wave propagation upon that the statistical parameters of amplitude fluctuations of the target reflection beyond the radiohorizon are distance dependent. Methods and Methodology. The basic mechanism of radio wave propagation beyond the radiohorizon is a phenomenon of tropospheric scatter on tropospheric heterogeneities in the upper tropospheric layers. These heterogeneities continuously change form and size and move through the space. The resulting electromagnetic field at the reception point represents additively combined radio wave powers scattered by all heterogeneities in the illuminated area that varies its height depending on the distance so that the statistical parameters of received signal fluctuations are distance dependent. After statistical processing of received signal fluctuations, the target distance can be determined. The present work examines radiowave propagation of the 3 cm and 50 cm waves over the Sea of Okhotsk with target distances up to 500 km. Results. For the target distance estimation by passive radar means, the standard deviation value, s, of the received signal amplitude can be employed. Conclusion. The distance dependence of the statistical parameters of amplitude fluctuations of the target signal allows the target distance to be estimated by a passive radar in the centimeter, decimeter and meter wave ranges.

34-39

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

Subject and Purpose. The maintenance of physical and chemical properties and biological stability of lubricoolants during downtimes, which are bound to happen sometimes and last long, is a hot problem in metalworking industry. The procedure of bubbling for the lubricoolant mixing, saturation with oxygen and inactivation of anaerobic microflora calls for chemical and biological techniques to monitor the lubricoolant condition during the bubbling and after it. Yet the standard methods lack responsiveness and accuracy of the analysis, implying the further refinement of the output values. In the present work, microwave super-high frequency (SHF) dielectrometry is employed for the examination of the dielectric constant and dynamic surface tension of synthetic, semi-synthetic and organic emulsions during the bubbling. Methods and Methodology. The dielectric constant and dynamic surface tension of 5.7 % water-soluble emulsions are measured at frequency f = 37.7 GHz. A frequency sweep in the acoustic frequency range f = 20…25000 Hz is used, for which purpose the end of the 8-mm waveguide is supplied with a piezo сell. Results. It has been revealed that the dielectric constant and dynamic surface tension of lubricoolants depend on the physicochemical characteristics that the lubricoolants acquire during a month-long downtime and after 10-, 20-, and 30-minute bubblings. The dielectric constant and dynamic surface tension demonstrate that the bubbling improves lubricating properties of all the emulsions examined. For this, a 10-minute bubbling is enough for semi-synthetic lubricoolants, and a 20-minute bubbling is needed for synthetic and organic lubricoolants. Conclusion. The microwave dielectrometry method with a frequency sweep in the acoustic frequency range can be used in metalworking industry as an aid to lubricoolant quality control during the downtime or storage.

3-10

Authors: А.М. Linkova

Subject and Purpose. Precipitation is the main source of agricultural land moisture. The knowledge of its amount, especially during the growing season, is important information to justify necessary agronomic and land reclamation measures. The purpose of this work is to solve by regularization the inverse problem of double-frequency sensing of precipitation in the microwave range with the signal attenuation considered and analyze the influence of radar cross-section (RCS) calculation errors and the total signal attenuation measuring precision on the rain intensity retrieval results. Methods and Methodology. Numerical simulation is used in double frequency retrievals to solve the integral scattering equation by regularization methods. Results. Numerical simulation has been performed for the rain intensity retrieval with a uniform spatial profile of rain intensity in the range 1…20 mm/h. Direct and inverse iterative procedures were used for having the signal attenuation at 0.82 and 3.2 cm operating wavelengths. It has been shown that the direct iterative procedure is less effective than the inverse one. Thus, when the rain intensity exceeds 20 mm/h or when it is within 10…20 mm/h and a rain spatial extent goes over 500 m, the direct iteration scheme causes significant errors in the rain intensity retrieval. Conclusion. The analysis of the results has shown that the use of the inverse iterative procedure makes it possible to retrieve a uniform-profile rain intensity with a 25 % error for rains with a 20 mm/h intensity and a 4 km spatial extent and ± 20 % errors in the total signal attenuation and specific RCS calculated.

18-23

Authors: O.V. Sytnik

Subject and Purpose. Smoke, fog, avalanches, debris of collapsed structures and other optically opaque obstacles in both natural and man-made disasters make optical sensors useless for detecting victims. Electromagnetic waves of the decimeter range penetrate well almost all obstacles, reflect from the trapped people and return to the radar receiver. Due to the breathing and heartbeat, the human-reflected sounding signals get the Doppler phase modulation, which is an information signal. These information signals and their properties provide the subject matter for the present research with the aim to create optimal methods and algorithms of random event processing for the prompt location of survivors by rescuers. Method and Methodology. The method of stochastic analysis of the fluctuation Doppler spectra of reflected sounding signals shows that the information signals have properties of conditional Markov processes. Results. The problem of optimal nonlinear filtering of conditional Markov processes entering the radar signal processing unit has been examined closely. An optimal adaptive filter has been proposed to reduce the masking effect of interferences caused by non-stationary noises and sounding signal reflections from stationary objects. The optimality criterion is the minimum mean square error function whose current value is evaluated in real time during the filtering process as the statistics is accumulated. The filter coefficients are calculated by the recurrent, steepest descent algorithm. The real-time work is carried out through the use of fast Fourier transform algorithms. Conclusion. The structure of the optimal adaptive filter to be built into the radar signal processing unit has been developed. Real radar signals have shown that the optimal filtering during the signal processing in systems designed for detecting live people by their breathing and heartbeat facilitates the interpretation of the observed signals. Some spectra of real signals generated by human breathing and heartbeat are presented.

30-37

Authors: Z.E. Eremenko, V.A. Pashynska, K.S. Kuznetsova, O.I. Shubnyi, N.I. Sklyar, A.V. Martynov

Subject and Purpose. This study focuses on the original waveguide-differential dielectrometer designed for complex permittivity measurements of high-loss liquids in the microwave range towards the determination of pharmaceutical ingredient concentrations in water solutions at room temperature. The suitability of the device and effectiveness of the dielectrometry method are tested on such pharmaceutical ingredients as lincomycin and levofloxacin over a wide range of concentrations. Methods and Methodology. The main idea of the method consists in that the complex propagation coefficients of the HE11 wave are obtained from the amplitude and phase shift differences acquired by the wave after it has passed through the two measuring cells of the waveguide-differential dielectrometer. Results. We have shown that the proposed dielectometry method allows a real-time determination of pharmaceutical ingredient concentrations in water solution by measuring the wave attenuation and phase shift differences. We have found that unless concentrations of pharmaceutical ingredients are low, few free water molecules in water solution are bound to the pharmaceutical ingredients. The number of free water molecules in solution decreases as the concentration of pharmaceutical ingredients rises. Conclusion. The current study confirms that the dielectometry method and the device developed provide effective determination of pharmaceutical ingredient concentrations in water solutions.

46-53

Authors: V.A. Kashpur, O.V. Khorunzhaya, D.A. Pesina

Subject and Purpose. The elucidation of the molecular mechanisms of action of biomolecules is necessary for the development of state-of-the-art means of diagnosing and treatment. Dielectric studies in the millimeter wave range are effective for puzzling out the nature of the interaction of biomolecules with a surrounding aqueous solvent. Flavin mononucleotide (FMN), which can kill microorganisms and destroy cancer cells, is of particular interest. The aim of the work is to recognize hydration effects (changes in the state of water molecules) in FMN solutions. Methods and Methodology. The complex dielectric permittivity (CDP) is measured in the EHF range. Knowing the difference between the CDP of FMN solution and the CDP of water we find the difference, D es , between the effective dielectric permittivities in terms of the Debye theory of polar liquids. Since the relaxation time of dipoles of bound water is one or two orders of magnitude longer than that of free water, the amount of the difference D es characterizes the hydration of biomolecules. At low concentrations, this difference is proportional to the number of bound water molecules. Results. It has been shown that approximately18 water molecules are bound to the FMN molecule. Groups of atoms as the most probable hydration centers (primarily due to the hydrogen bonds) have been indicated. As the pH decreases, the number of water molecules bound to the Flavin mononucleotide increases to 21. The study of the FMN–DNA solution has shown that one nucleotide accounts for 25–26 bound water molecules in total. However, composing hydration numbers assumes a quantity of components less than 20. An assumption is made that the additional components are due to the cooperative nature of the hydration, leading to the fact that even if some solvent molecules do not come into a direct contact with hydration centers, they are under the influence of biomolecules all the same. Conclusion. Extremely-high-frequency dielectrometry is an effective method of research into the interaction of biomolecules with a water-ionic solvent. A FMN hydration model has been proposed, which indicates probable hydration centers and tells a measure of their effect on the solvent. It has been found that the FMN with DNA interaction increases the number of bound water molecules per one nucleotide of the DNA. The obtained results have been compared to the existing models of the DNA with FMN interaction.

3-9

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

Subject and Purpose. In the context of growing anticipation of fundamentally new optical and radiophysical devices, the present study is concerned with the total electromagnetic wave tunneling through an asymmetric three-layer structure such that contains a conductive negative-permittivity layer. The aim of this work is to recognize how the asymmetry property of this three-layer structure acts on the effect of total wave tunneling with the frequency dispersion of the conductive negative-permittivity layer taken into account. Methods and Methodology. The frequency-dependent conditions of the total electromagnetic wave tunneling through an asymmetric three-layer structure are sought by numerical simulations. A universal approach based on the introduction of dimensionless frequencies and dimensionless layer thicknesses allows us to numerically investigate conditions of the total electromagnetic wave tunneling for any desired frequencies and geometric parameters of the asymmetric three-layer structure. Results. It has been shown that the asymmetry property of the three-layer structure can significantly change the total electromagnetic wave tunneling conditions. It has been demonstrated that parameters of the asymmetric three-layer structure can be selected in such a way as to modify the total electromagnetic wave tunneling conditions toward a desired practical application of the structure. It has been found that a proper choice of the parameters can minimize the action of the three-layer structure asymmetry on the electromagnetic wave tunneling effect. Conclusion. Asymmetric three-layer structures can be of use to effectively change conditions of the total electromagnetic wave tunneling in an effort to provide devices under development with desired characteristics.

16-22

Authors: А.М. Linkova

Subject and Purpose. The amount of precipitation is important information for the agro-climatic justification of agro-technical and reclamation actions directly controlling crop yields. The inverse problem of rain intensity retrieval from the remote sensing data is an incorrect mathematical physical problem described by a nonlinear integral equation. The purpose of this work is to analyze how errors in the specific effective scattering surface evaluation affect the results of double-frequency retrieval of the rain intensity obtained through the inverse problem solution by the previously proposed method. Methods and Methodology. Numerical simulation by using an approach based on regularization techniques and intended for the integral scattering equation solution is carried out for double-frequency sensing in the microwave range Results. Numerical simulations of the rain intensity retrieval have been performed at the operating wavelengths 0.82 and 3.2 cm in the range 1…30 mm/h and for different values of received power errors. It has been shown that an error in the specific effective scattering surface evaluation has a greater effect on the reliability of the intensity retrieval in the shorter wavelength case. And it exerts practically no effect (not exceeding 5 %) at the longer wavelength and at the rain intensity below 15 mm/h, which, however, is true for heavier rains, too. Conclusion. The analysis of the results has shown that the error of the rain intensity retrieval remains within acceptable limits (below 20 %) provided that the error in the specific effective scattering surface evaluation does not exceed 15 % at the shorter wavelength. At the longer wavelength, it can reach 30 %.

32-36

Authors: K.Yu. Sova, A.S. Vakula, S.Yu. Polevoy, S.I. Tarapov

Subject and Purpose. The development of technologies for synthesis of nanoscale magnetic materials requires new techniques for measuring magnetic properties of nanoscale magnetic materials in such a way as to provide express post-synthesis measurements of magnetic properties and exclude, in doing so, any mechanical displacements of measured specimens. Despite the fact that numerous techniques exist for studying magnetic properties of materials, the development of such magnetic nanomaterials as magnetic nanoparticles faces the need in novel measuring approaches based on standard procedures. Novel express techniques are called to gain information about how magnetic properties of magnetic materials vary over time and respond to such factors as temperature, storage conditions, stabilizing agents, exposure to an external magnetic field. Method and Methodology. In this work, magnetic hysteresis loops are registered using a newly developed technique based on the method of small disturbances (by an external magnetic field) and combining standard constructions of hysterometers and vibrating-sample magnetometers. Results. Magnetic hysteresis loops of a bulky ferrite (brand 1SCh4) sample and a 40 μm thick YIG film have been registered using the presented technique and compared with the results obtained by the well-known technique for measuring magnetic hysteresis loops. They are in good agreement with a margin error as low as 10%, which can be further improved by means of more precise equipment. With the presented technique, the magnetization and the coercive force of Fe0.5Co0.5Fe2O4 nanoparticles not examined yet have been determined. Conclusion. The developed technique makes it possible to study magnetic materials of various compositions including nanoscale magnets.

46-53

Authors: I.G. Skuratovskiy, O.I. Khazov, A.S. Shakhova

Subject and Purpose. Tunable resonant structures make numerous microwave devices, among which are waveguide-dielectric and waveguide-coaxial resonators (WDR and WCR) built around cylindrical evanescent waveguides and involving a resonant short-circuit (RSC) plunger for tuning purposes. The present paper seeks to study specific features of the RSC-plunger operation in the evanescent waveguide and estimate the RSC-plunger efficiency. Method and Methodology. The RSC-plunger efficiency is approximately estimated in terms of the transmission line theory. Comparative experimental verification of the Q-factor increase is provided by an example of a 3 cm WDR resonator equipped with a RSC-plunger. Results. It has been shown that relevant formulae of the transmission line theory can be extended for the RSC-plunger efficiency estimation on the TEM and H11 oscillations. A possibility has been studied of the TEM type transformation to the H11 oscillation and back when the spurious resonance of the RSC-plunger falls within the WDR (WCR) tuning range. Conclusion. Insignificance of the effect that small deviations from the numerically predicted dimensions of the RSC-plunger exert on the RSC-plunger operation efficiency has been demonstrated. The RSC-plunger efficiency and a possibility to remove the spurious resonances from the resonator tuning range have been experimentally confirmed.

3-11

Authors: S.A. Velichko, А.Ya. Matveev, D.M. Bychkov, V.K. Ivanov, V.N. Tsymbal, O.S. Gavrilenko

Subject and Purpose. The paper addresses interaction processes going in the ocean–atmosphere system and is concerned with their research by the method of radar remote sensing. Specifically, the matter of concern is the detection and parameter estimation of long waves, including nonlinear ones, on the ocean surface. Methods and Methodology. In August 1988, a series of successive radar surveys of long surface wave manifestations on the Pacific Ocean surface was carried out in the 3 cm wave range by means of an airborne X-band radar system “Analog”. The analysis of the results includes estimation of both spatial and frequency features of the detected long-wave packets and, also, a comparison of the measurement results with model calculations performed in the framework of theory of radio wave scattering by the sea surface in the presence of seismic wave effects. Results. Radar images of wave packets of long surface waves in the open ocean have been obtained. From the imaging data, the spatial scale (5…10 km) of these waves, the lengths (1…5 km) of wave packet components and the wave packet velocity (6.1 m/s) have been derived. Analysis has been given to the nonlinear form of wave packet components, and their amplitudes have been estimated by comparing the experimental and theoretically obtained radio contrasts. The bathymetry of the surface-wave track has been performed to suggest that the observed wave packet represents a set of solitons generated by a seismic impact with the further underwater collapse. Conclusions. A possibility has been demonstrated for monitoring wave packets of long surface waves in their propagation dynamics. The experiments of the sort for gaining a deeper insight into the ocean–atmosphere interaction physics can be conducted by means of not only airborne but also spaceborne radar systems with allowance made for the rate of surveys in both time and space.

20-27

Authors: V.B. Sinitsky

Subject and Purpose. The paper investigates tropospherically caused fluctuations of signals from the GPS navigation system while the satellite is beyond the radio horizon. The intensity of GPS signal fluctuations under the influence of meteorological factors is studied, too. The purpose of the work is to determine relationship between the intensity of GPS signal fluctuations and the meteorological conditions when satellite elevation angles are small. Methods and Methodology. The methodology of the work is based on the search for the intensity of amplitude fluctuations of GPS satellite’s signals depending on the meteorological situation. The measurement approach is registration of the GPS satellite’s signal level just before the satellite crosses the horizon. The data processing after a series of experimental studies is based on the extraction of tropospheric fluctuations from the complete GPS signal by the moving average method. Results. Experimental studies of the turbulent component of signals from GPS satellites at low elevation angles have been carried out. It has been revealed that a conventional elevation boundary below which the tropospheric influence is predominant can be established due to the synchronism property which the orbits of the GPS satellites hold. It has been shown that variations in the mean square deviation (MSD) of GPS signal fluctuations caused by the troposphere and extracted from the complete signal are consistent with meteorological parameter changes. Conclusion. Analysis has been carried out to show that a meteorological dependence of the MSD statistics of GPS signal tropospheric fluctuations exists. The intensity of fluctuations rises with the convective activity in the troposphere. The conducted experiments suggest that periods of increased turbulence in the atmosphere can be detected with the use of GPS signals. For this purpose, the optical methods will not do.

35-40

Authors: V.V. Ovsyanikov

Subject and Purpose. Two types of new dual-frequency microwave antennas with coaxial and two-wire shunts are considered with a view to improve calculation methods of radio engineering and design parameters of the antennas of the kind. Methods and Methodology. The mathematical methods of equivalent long line and the method of integral equation and optimization of objective functions are used, involving set-point and current values of the voltage standing-wave ratios at the antenna input connectors in the two operating frequency bands. Results. The research and development results have been presented for two variants of dual-frequency (dual-band) vibrator antennas according to whether the shunts are placed inside metal radiating tubes or outside the central conductive rod of the antenna. The shunts are in coaxial and two-wire versions. As applied to the first antenna variant, the method of shunt length optimization upon a minimization of the objective functions yields desired values of antenna electrical parameters (voltage standing-wave ratio, radiation patterns, etc.). For the second antenna variant with both coaxial and two-wire external shunts and provided that the design and operation principle of these antennas are similar, conditions under which the double-frequency mode is possible have been determined for the first time. Conclusion. The proposed method of design and development of tubular dual-frequency vibrator antennas with coaxial shunts has been used to yield a two-frequency circular (elliptical) polarization turnstile antenna as part of sea buoys in the project "Ocean" of the National Space Agency of Ukraine and other spaceborne dual-frequency antennas. The new dual-frequency microstrip antenna discussed in this paper saves us significant drawbacks peculiar to the known dual-frequency antennas and can be used aboard spacecraft and other mobile objects due to its small size.

49-57

Authors: O.A. Lavrinovich, M.T. Cherpak

Subject and Purpose. The mechanism of destruction of the S-state of a nonlinear high-temperature superconductor as part of a coplanar waveguide has not been properly elucidated as the effect of avalanche-type transition to a highly dissipative state, which was experimentally detected by the authors, takes place. The present work is concerned with the development of an appropriate approach describing kinetics of destruction of the S-state of a nonlinear high-temperature superconductor in a coplanar waveguide with allowances made for an inhomogeneous distribution of the microwave current in the superconducting film strip. Methods and Methodology. Use of I.B. and O.G. Vendiks’ reasoning [2] is made on kinetics of the destruction of the superconducting state of a wide film when a direct current governed by the time-dependent Ginzburg-Landau equation is applied. Keeping unchanged their idea as to the S–N boundary forming in the film strip with the boundary movement to the middle of the strip, the S–N boundary motion equation is obtained for a coplanar waveguide, proceeding in doing this from the motion equation of magnetic flux vortices under certain restrictions specified. Results. The time of S-state destruction has been numerically estimated: 1) for a wide superconducting film of YBa2Cu3O7–d composition, the destruction is by the direct current and 2) for a coplanar waveguide based on the same film, the destruction is by the microwave current. When the superconductivity is small (I / I c ³ 1), the destruction time values in both cases are close to each other within the order of magnitude. Conclusion. It is for the first time that the S-state destruction time in a coplanar waveguide has been expressed in terms of the microwave current distribution in the waveguide. It has been shown that this characteristic linearly depends on the ratio between the critical current and the microwave current amplitude in contrast to a quadratic dependence obtained for a superconducting strip with a direct current.

3-9

Authors: Yu.V. Svishchov

Subject and Purpose. The spectral characteristics (eigenfrequencies, eigenmodes, Q-factors) of a spherical particle with arbitrarily valued permittivity and permeability are considered to take a further look into some important features of their behavior. The real and imaginary parts of the material parameters of the particle can be both positive and negative. The emphasis is on magnetic type modes. Methods and Methodology. The spectral problem is solved using the electromagnetic field expansion in vector spherical wave functions. Results. The first eigenfrequencies of a spherical particle have been calculated depending on its relative permittivity e 1 and relative permeability m 1 whose real and imaginary parts can take both positive and negative values. The eigenmodes split into two, internal and external, eigenmode families. The internal eigenmodes bear an independent, associated with eigenmode structure labeling in each quadrant of the plane (m 1 , e 1). The external eigenmodes, on the contrary, have a uniform labeling throughout the whole (m 1 , e 1) plane and bear a structural resemblance to surface plasmon oscillations distributed in the vicinity of the particle surface or outside it. In the first quadrant of the plane (m 1 , e 1), the external eigenmodes repeatedly interact with the internal eigenmodes, leading to either mode hybridization or mode type exchange. In the third quadrant of the plane (m 1 , e 1), the external eigenmodes can interact with one another. The anomalous behavior of the spectral characteristics of a spherical particle corresponds to the already known phenomenon of wave mode coupling described in the scientific literature well enough. Conclusion. The performed study has revealed some new behavioral patterns as to the spectral characteristics of a spherical particle with arbitrarily valued permittivity and permeability

18-29

Authors: R.E. Pashchenko, V.K. Ivanov, D.O. Tsyupak

Subject and Purpose. Comparative analysis of the shapes of phase portraits of Doppler signals (DS) reflected from drone rotating rotors is given with regard to different time delays. The shapes of DS phase portraits are examined for various rotational velocities and numbers of the rotating rotors. Methods and Methodology. A method using phase portraits is suggested for analysis of Doppler signals reflected from drone rotating rotors. The method determines the number of the rotors and estimates their rotational velocities. Results. It has been found that the shape of the phase portrait of the baseline signal is practically independent of the time delay and can be described as an occasional movement of the image point following the phase trajectory in the center of the phase portrait. The appearance of characteristic regions on the periphery of the phase portrait allows separating baseline and sounding signals. It has been shown that the shape of the DS phase portrait of the rotating rotor during the flight movement of the drone depends on the time delay value. With a larger delay, phase portraits similar in shape appear at regular intervals equal to the Doppler signal period. With a larger rotational velocity of the rotor, the rate of similar phase portrait appearance diminishes. Conclusion. During the sounding of drone rotating rotors, the shapes of DS phase portraits depend on the value of time delay. With a larger number of rotors in the drone flight, the periodic change character as to the DS phase portrait shape remains unchanged. In this case, DS phase portrait shapes differ substantially for different numbers of drone rotors

38-53

Authors: M.V. Mil’cho, K. Ilyenko

Subject and Purpose. A special need for oscillators amenable to operation in the short-wave end of the submillimeter wave band sends us in search for new ways of their development. A proposal exists related to vacuum-tube frequency multipliers based on the backward-wave oscillator (BWO) or its variant, the clinotron. Sometimes a simultaneous excitation of two different-frequency oscillations is experimentally observed in ordinary millimeter wave clinotrons, orotrons and diffraction radiation oscillators. The aim of the present study is to examine whether those operational regimes can be implemented in the creation of electronic frequency multipliers in the submillimeter wave band. Methods and Methodology. The research method is a theoretical analysis of the process of simultaneous interaction of the electron beam with the electromagnetic fields of two modes in the BWO slow-wave structure. The aim is finding relationships to impose on the slow-wave structure parameters and the BWO operation figures and thus furnish a simultaneous excitation of the two modes. The obtained relationships are tested against published experimental results. Results. Two conditions of simultaneous mode excitations have been formulated, requiring (i) equal velocities of the operating spatial harmonics and (ii) their strict frequency multiplicity. Handy diagrams have been constructed, which made it possible to build frequency multiplication schemes with any multiplicity. The rigorous analytical method of comb dispersion calculation has been generalized to the higher passbands of large numbers. The calculation results have been compared with relevant experimental data, lending support to the validity of the obtained formulas to describe the frequency multiplication regime. Conclusion. A possibility has been theoretically shown of designing submillimeter vacuum-tube frequency multipliers upon clinotron-type oscillators with a single slow-wave structure. The regime of simultaneous generation of two given frequencies requires that the system dispersion in different passbands be controlled by moving a screen over the comb-type slow-wave structure.

66-79

Authors: A.O. Puzanov

Subject and Purpose. The present paper is concerned with the method of surface schooping of materials using high-frequency torch discharge (HFTD) and glycerol vapor as a base for dissolving activating additives to the working gas. To approach the problem, a steam generator is employed in an effort to improve the HFTD catalytic performance in the activation of surfaces and deposition of coatings on them. The purpose is to develop a design technique of a steam generator intended for making a proper gas environment in the HFTD burning area. The discussed design techniques seek to enhance efficiency of the self-contained steam generator with allowance for its small size compared to the wavelength. Methods and Methodology. The analysis of the glycerol vapor behavior in the HFTD plasma depends on the knowledge of glycerol molecule ionization potential in the electron impact case. To find out about the measure to which the glycerol vapor affects the HFTD current, a known calcium ionization potential is used as a defined point. The heating elements as part of the steam generator are designed in terms of thermal design methodology adopted in the electroheating machine making. The calculation formulas of the running time ratios of the steam generator with various heating elements and energy efficiencies have been obtained in terms of galvanic cell theory. Results. It has been shown that glycerol vapor itself cannot affect the HFTD current. For the HFTD excitation, the microwave region has been chosen. In cooperation with activating additives to the discharge plasma, this factor also adds to the HFTD current increase. Hence, the HFTD catalytic performance depends not only on the HFTD energy and its excitation field frequency but on the glycerol-dissolved additives as well. A special design has been developed for the heating element as part of a small-size steam generator. Reference tables have been composed, enabling one to pick up a prpoper diameter and number of parallel connected wires in the spiral coil. Conclusion. A good use of glycerol vapor as a base for vaporous fluxes and activating additives to the HFTD working gas has been shown. The developed design technique concerning the heating element of the steam generator optimizes its heating circuit. Specifically, it enhances the steam generation and reduces the power consumption of the steam generator running on the galvanic cell. Second, it makes it possible to use stainless-steel spiral heating coils in regime of automatic temperature control.