A.A. Kirilenko and S.A. Steshenko
A. Usikov Institute of Radio Physics and Electronics, National Academy of Sciences of Ukraine
12, Academician Proskura St., Kharkov 61085, Ukraine
Optimization of a Waveguide with a Corrugated Flange on the Basis of Genetic Algorithms

The accurate two-dimensional mathematical model of radiation of the H-polarized wave from a waveguide with a corrugated flange has been developed. Grooves of arbitrary rectangular profile are symmetrically cut of about the waveguide axis. This structure can be considered as the two-dimensional model of the surface-wave antenna with a slow-wave structure having finite number of grooves. The problem of synthesis of the narrow beam width with given side lobe level has been solved with use of genetic algorithms.

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N.G. Don, A.Y. Poyedinchuk, and V.I. Tkachenko
A. Usikov Institute of Radio Physics and Electronics, National Academy of Sciences of Ukraine
12, Academician Proskura St.,61085 Kharkov, Ukraine
Numerical-Analytical Computation Method for Cutoff Wavenumbers of Waveguides with Complicated Cross-Section

The paper considers a new numerical-analytical technique for computing the cutoff wavenumbers of hollow regular waveguides having a continuous curvature of the cross-section contour or a curvature with a first kind singularity. The method is based on the boundary integral equations of the potential theory and a special parameterization of the cross-section contour. The details of the numerical implementation are illustrated by a circular waveguide and a rectangular one with rounded corners. The perturbation theory is employed to derive the analytical formulas for the cutoff wavenumbers of waveguides with piecewise linear boundaries and rounded corners. The application range of these formulas is determined.

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V.V. Yachin
Institute of Radio Astronomy, National Academy of Sciences of Ukraine,
4, Krasnoznamennaya St., Kharkov 61002, Ukraine
Suppression Principle in the Problems of Scattering by Double-Periodic Magneto-Dielectric Structures

The paper deals with a new method of solving scattering problems for double-periodic magneto-dielectric structures. This method is based on volume integro-differential equations. The specificity of this technique is that the suppression principle is applied instead of the conventional boundary conditions.

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L.P. Yatsuk, T.G. Nazarenko, and K.N. Mistrekov
V. Karazin National University of Kharkov,
4, Svoboda Sq., Kharkov, 61077, Ukraine
Scattering from Slots in a Waveguide with Imperfectly Conducting Walls

The problems of the theory for a narrow longitudinal slot cut in a wide imperfectly conducting wall of a rectangular waveguide are considered. Reflection, transmission, and radiation factors of the slot as well as ohmic losses in the waveguide walls in the vicinity of the slot are examined.

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V.N. Kochin
Institute of Radio Astronomy, National Academy of Sciences of Ukraine
4, Krasnoznamennaya St., Kharkov 61002, Ukraine
Modeling a Non-Symmetrical Vertical Vibrator of Finite Thickness upon Axially Symmetric Excitation

The problem of radiation of a non-symmetrical cylindrical vibrator of an arbitrary radius upon axially symmetric excitation is investigated by a rigorous method. The ground of the suggested approach is a representation of surface currents flowing on the vibrator as an expansion in basic functions of subdomains on the vibrator surface. The solution of the mentioned problem is reduced to an infinite set of algebraic equations for unknown coefficients of the current expansion with a matrix consisting of generalized impedances and voltage vector in a right part of the system. The currents flowing on the cylindrical surface were calculated and the comparison of results obtained with known ones was carried out. The formula for field calculation in far-field zone and the dependences of antenna input impedance versus frequency are given as well.

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A.V. Gribovsky
Institute of Radio Astronomy, National Academy of Sciences of Ukraine
Krasnoznamennaya St., Kharkov 61002, Ukraine
A New Method of Controlling the Radiation in a Waveguide Phased Array

A novel method of exciting and controlling the radiation of a phased array formed by open ends of a rectangular waveguide, using a surface wave of a planar dielectric waveguide is suggested. The method enables beam-scanning while the surface wave in the array aperture changes its propagation direction.

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O.I. Sukharevsky, V.A. Vasilets, S.V. Nechitaylo, and S.V. Orekhov
Kharkov Military University,
6, Svoboda Sq., Kharkov, 61043, Ukraine
Calculation of the Side and Back Far-Field Zone Radiation for Reflector Antennas with Radio Absorbing Coating on Edges

It is proposed calculation technique of a reflector antenna pattern which edge is covered with the toroidal radio-absorbing coating. The results of calculation of patterns for reflector antennas fitted with radar absorbing coatings of different radii and types are presented.

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L.E. Kopilovich
A. Usikov Institute of Radio Physics and Electronics,
National Academy of Sciences of Ukraine 12, Academician Proskura St., Kharkov 61085, Ukraine
Difference Bases for Hexagonal Grids

Definition is introduced for difference basis for a hexagonal grid as a configuration of elements that ensures complete covering of a hexagonal region in a plane of spatial frequencies. The configurations having three-order symmetry and being difference bases for hexagonal grids of a prescribed (arbitrary) radius are constructed.

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Ò.À. Protasova
Sumy National University, Sumy, Ukraine
Method of Optimal Encoding of a Probabilistic Stationary Source of Information

The paper presents the method of optimal encoding that uses as the basis of its operation the decomposition of the initial probabilistic stationary source of information into two interrelated ones. The method is solving the problem of decreasing the complexity of the entropy calculation.

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