Radio physics and electronics

16-21

Authors: V.M. Gorobets’, M.I. Golovko, S.M. Zotov, L.O. Kovorotny

Subject and Purpose. The article is devoted to the radio recognition of moving waterborne objects (sea-going ships). The problem lies in the lack of radar signatures, which is especially true for coherent radar in continuous mode, implying that more signatures for the waterborne object recognition is highly needed. An additional signature can be gained just by means of a simple mathematical processing of target reflection signals. This is particularly important for radio recognition systems in current use because this will hardly complicate the system structure. Hence, it will not affect its cost either. Methods and Methodology. The method developed for the retrieval of an additional radar signature characteristic of waterborne objects moving across a rough sea surface is based on a simple mathematical processing of a signal reflected from the moving waterborne object and taken from the phase output of coherent radar. The method approbation is by the mathematical modeling of signals at the phase detector output in the event of three waterborne objects such that have identical scattering cross sections but different periods of the side and keel vibrations. Results. Based on the mathematical modeling results, it has been shown that each of the local scattering centers keeps the ratio of the linear speeds of side and keel vibrations approximately the same for the same object. But the employed ratio takes different values for different objects. Conclusion. Having a single standard coherent radar in continuous mode and guided by the developed methodology, one can gain an additional signature for the target recognition, which is a ratio of the linear speeds of side and keel vibrations of the target. The suggested methodology can be used for the radio recognition of waterborne objects moving across a rough sea surface.

28-33

Authors: M.I. Dzyubenko, S.O. Masalov, Y.E. Kamenev, I.V. Kolenov, V.P. Radionov, N.F. Dakhov, А.I. Puzak, O.I. Dmitruk

Subject and Purpose. The problem of output beam matching with the waveguide transmission line often arises when using terahertz lasers. The special quasi-optical devices that are used to combat the problem lead to radiation losses and additional material costs. The aim of this work is to develop appropriate output mirrors for THz lasers so as to make the output laser beam match the transmission line of a given diameter. Methods and Methodology. As part of the experimental research into the action of the output mirror configuration on the parameters of THz laser radiation, gradient metal-film mirrors are made like a transparent substrate with a thin metal layer on it. The layer thickness varies over the substrate surface, forming therewith a transparency spot with a given change in the transmittance in the middle of the mirror. The properties of the gradient metal-film output mirrors are examined as applied to a gas-discharge HCN laser at a wavelength of 337 μm. Results. The gradient metal-film mirrors enable obtaining laser beams of a diameter equal to the inner diameter of the relevant transmission line and with a proper transverse energy distribution. The efficiency of the transmission of laser radiation energy into the waveguide line increases, and so does the performance of the laser installation. Another positive point is that the enhanced transparency in the middle of the mirror raises efficiency of the active substance energy utilization and conveys focusing properties to the flat mirror, which reduces diffraction losses. Conclusions. The employment of gradient metal-film output mirrors makes it possible to raise efficiency of laser installations. The features of metal-film mirrors suggest broad potentials for their application and make reasonable their further research.

40-50

Authors: O.I. Kovalenko, S.V. Kalinichenko, E.M. Babich, F.V. Kivva, O.M. Roenko, T.I. Antusheva

Subject and Purpose. The present paper is concerned with the use of wave technologies in the development of antibiotics-alternative approaches for pathogenic microflora suppression. Lactobacilli strains picked in different ecological niches and their activity against pathogenic strains are studied with a focus on a targeted modification of adhesive and antagonistic properties of lactobacilli by exposing them to low-intensity electromagnetic (EM) fields and the ultrasound. Methods and Methodology. Lactobacilli picked in different ecological niches are experimentally studied, including (1) standard strains from probiotic preparations and (2) circulating strains picked in humans and bees. For the ultrasonic and electromagnetic radiation sources, G3-109 and G3-F and G4-141 and G4-142 generators are taken, respectively. The adhesive properties of Lactobacillus spp. strains and their antagonistic activity are estimated against C. diphtheriae, S. aureus and yeast-like fungi of Candida genus in aerobic and microaerophilic culture conditions. Statistical technology is employed in the data processing and analysis. Results. It has been established that L. plantarum strains picked in the gut of healthy bees are most antagonistic towards pathogens. It has been demonstrated that the priority culture conditions for lactobacilli are microaerophilic conditions simulating their stay in vivo. It has been shown that it is possible to modify properties of microorganisms by their exposure to ultrasound and low-intensity electromagnetic fields in narrow bands of the EHF range. The effect efficiency versus frequency has a dispersion character. Individual features of various pathogenic strains have been recognized. Conclusion. The obtained results open up prospects for electromagnetic and acoustic technologies in the development of safe alternative means to antagonize persisting pathogens and increase human body resilience.