Radio physics and electronics

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.