S.N. Razinkov − Dr.Sc. (Phys.-Math.), Senior Research Scientist, Leading Research Scientist,  Research Test Center of Radioelectronic Struggle Military Educational-Scientific Center of Air Forces  of the «Military-air academy named after professor N.E. Zhukovsky and Yu. A. Gagarin» (Voronezh) E-mail: razinkovsergey@rambler.ru

S.O. Barаnоv − Ph.D. (Eng.), Senior Research Scientist, 

Research Test Center of Radioelectronic Struggle Military Educational-Scientific Center of Air Forces  of the «Military-air academy named after professor N.E. Zhukovsky and Yu. A. Gagarin» (Voronezh) E-mail: vaiu@mil.ru

O.E. Razinkova − Ph.D. (Eng.), Senior Research Scientist, 

Research Test Center of Radioelectronic Struggle Military Educational-Scientific Center of Air Forces  of the «Military-air academy named after professor N.E. Zhukovsky and Yu. A. Gagarin» (Voronezh) E-mail: olga-razinkova@rambler.ru

Using the method of induced currents to calculate fields of an object with axial symmetry, an electro-dynamic model was built and analysis of radiation and scattering of electromagnetic waves was carried out by arrays of elementary electric vibrators located on the side surface of an ideal conducting cylinder of finite length. The studies were carried out in the interests of developing methodological bases for the construction of unmanned radio-electronic complexes intended for operation in conditions of protection against radar reconnaissance facilities. Low-profile antenna systems have small weight and size indices and when placed on board slightly change aerodynamic properties and level of secondary carrier field. At the same time their directed properties depend significantly on shape, electric dimensions and electro-physical parameters of surfaces intended for placement. Diffraction of electromagnetic waves on bearing surfaces results in shielding of antenna systems. Effects of change of parameters of spatial-frequency selectivity of transmission-reception of signals, reduction of energy potentials of radio channels, formation of spatial-correlated interference, frequencytime parameters of which are identical to parameters of processed radiation, occur.

Linear antenna arrays have significant directional action coefficients and capabilities to control directional patterns due to amplitudephase correction of current of elements without using complex switching devices. Representation of antenna elements of small electric length by dipoles is possible due to constant values of amplitudes and phases of currents at each point of surface. Side surface of cylinder of resonance electric dimensions can be approximated by fuselage of small-size unmanned aerial vehicle of aircraft type. By selecting values of complex dielectric constant of material from which cylinder is made, reflecting properties of aerial object with reduced radar visibility are reproduced.

Сharts of directional and bi-static scattering of antenna arrays are investigated based on asymptotic estimates of total electric field of vibrator system and cylinder in far zone. The polarizing components of the magnetic and electric fields on the side surface of the cylinder were represented by equivalent currents approximated by rows of cylindrical functions; Lattice fields in the far zone of the cylinder were by summing up rows of trigonometric functions of azimuth harmonics of its equivalent currents with weight coefficients. Rows of azimuth harmonics of cylinder side surface currents are characterized by fast convergence when its radius belongs to resonance area. The antenna array performance values were using C++ computer program for a computer with an Intel Core i7-8700 processor with 16 GB RAM.

Patterns of change of directed properties of arrays with different number of antenna elements are revealed. Due to the formation of the array field not only by the currents of the antenna elements, but also by the surface currents of the cylinder, its beam patterns and bistatic scattering differ significantly from the characteristics in the free space. A significant difference is evident in the change in the shape of the main beams and the appearance of the side lobes of the diagrams due to the secondary radiation of the bearing surface. The shapes of the linear lattice diagrams in the meridian plane of the cylinder, like those of a single elementary electric vibrator, have petal structures. As the number of antenna elements increases, the width of the array pattern decreases the faster the greater the ratio of inter-element distance to wavelength. Increasing the inter-element distance within the wavelength does not significantly change the directional factor. The narrowing of the bi-static scattering pattern as the wavelength decreases is due to the increasing electromagnetic interaction between the vibrators by increasing the flow density of the secondary field.

For an antenna array made of small electric length vibrators, significant directivity indicators can be achieved at a low level of secondary field radiation, which allows to ensure low radar visibility of the unmanned aerial vehicle.

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