Search

Search Results

• SUBTRACTION OF BACKPROPAGATION INTERFERENCE BASED ON POLARIZATION IN UNDERWATER VISION SYSTEMS FOR OPERATION IN TURBID WATER

  N.А. Budko, А.Y. Budko, М.Y. Medvedev

  2022-08-09

  Abstract ▼

  The study of the sea depths in order to ensure safety, the effective use of underwater resources
  is an urgent task. The first part of the article briefly considers the physical phenomena and
  limitations that arise during the propagation of electromagnetic waves in the visible range in the
  underwater environment. It is shown that underwater vision systems (as a class of specialized
  technical vision systems - TVS) based on conventional CCD matrices face a number of fundamental
  limitations in terms of improving the efficiency of functioning in natural water of low transparency.
  In particular, the use of artificial light sources as part of underwater vision systems in turbid
  water leads to the occurrence of backpropagation interference (BPR), which leads to spurious
  illumination of the optical device matrix. As a promising direction in the development of underwater
  vision systems, it is proposed to use methods for subtracting POR based on information about
  the polarization of light. In the review part of the article, the latest achievements in this field are
  considered. The main part of the article presents the methodology for studying the proposed method
  for subtracting the POR based on a comparison of the results obtained by processing images
  with known methods for estimating the Stokes vector parameters DoLP and AoLP, which allow
  obtaining information about the degree of polarization and the prevailing polarization angles of
  the scene, respectively. The experimentally obtained results of processing an underwater scene in
  water of varying degrees of turbidity using the DoLP, AoLP algorithms and the proposed methods
  for subtracting the POR are presented. Distinctive features are the use of four rather than two
  polarization directions in calculations, as well as the original mathematical apparatus for processing
  signals from the machine vision camera matrix.

• PRINTED LATTICES APPLICATION TO ELECTROMAGNETIC WAVES POLARIZATION CONTROL AT MICROWAVES

  А.О. Kasyanov

  38-60

  2025-07-31

  Abstract ▼

  The paper is devoted to consideration of variants of solution to some problems of diffraction
  for printed arrays with anisotropic inhomogeneities. The rotation of the plane of polarization is
  realized by means of a twist-reflector. On the basis of computational and full-scale experiments it
  was shown that twist reflectors based on microstrip reflective type antenna arrays (RAA) can be
  quite broadband. The obvious advantage of such twist-reflectors is simplicity of the technology of
  their manufacture, small thickness and weight. In addition, in twist-reflectors based on printed
  RAA, it is possible to constructively realize the necessary phase distributions of the field on their
  surfaces. Thus, it becomes possible to use such twist-reflectors to create phase-correcting twistreflectors.
  It is shown that introduction of impedance loads in the construction of the re-radiating
  elements of the printed RAA opens additional possibilities for controlling the field scattered by it.
  Thus, twist reflectors with improved characteristics can be realized on the basis of microstrip-pin
  RAA. The results of numerical studies based on the author algorithms and computational programs
  are presented. Besides, spatial polarizing filters and a controllable twist-reflectors based
  on microstrip RAA are considered. If microstrip elements of a twist-reflector contain controllable
  loads, then qualitatively new type of the microwave device is formed. This device enables to control
  polarization of the scattered field. Such devices can be named by polarizing modulators or
  manipulators. By means of printed RAA with elements of complex topology the spatial polarizers,
  which can transform electromagnetic waves with linear polarization in waves with rotating polarization
  and, in particular, in waves with circular polarization, are realized

• STUDY OF GENERATING CAPACITY OF PIEZOCERAMIC ELEMENTS BASED ON LEAD ZIRCONATE-TITANATE WITH LOW TITANIUM CONTENT

  L.A. Dykina, А. А. Panich, A.V. Skrylev, Y.A. Proskoryakova

  2021-02-13

  Abstract ▼

  This article is devoted to PZT-based solid solutions as the basis of active elements for
  single-use pulsed energy sources. The article evaluates the generating ability of a
  piezoceramic material based on lead zirconate-titanate with a low titanium content
  (Zr/Ti 0,94/0,06 + 1 % Nb2O5) under its shock loading. In such materials, the pressureinduced
  (uniaxial, pulsed hydrostatic, or shock wave) phase transition occurs from the polar
  ferroelectric phase to the non-polar antiferroelectric phase. The released energy in this case
  is an order of magnitude higher than with the piezoelectric effect. A measure of the accumulation
  of electrical charge is the value of the residual polarization, which is proportional to
  the electrical energy released during the phase transition. In the course of the work, the main
  electrophysical parameters of the material under study were obtained: relative dielectric
  constant, dielectric loss tangent in weak fields, piezoelectric charge constant . A number
  of numerical values of the residual polarization of the material under study were obtained by
  several methods: thermal depolarization and shock loading; the accumulated energy density
  is calculated as the ratio of the residual polarization to two absolute dielectric constants. An
  assessment of the generating capacity of the material under study and a comparative analysis
  with the industrially produced piezoceramic material PZT-19 are carried out. It was found
  that the density of the accumulated energy of the material under study is two orders of magnitude
  higher than that of PZT-19. It is also worth noting that the pressure-induced phase transition
  from the ferroelectric to antiferroelectric phase for materials with a low titanium content
  occurs at much lower pressures than in materials located near the morphotropic boundary.
  This behavior is due to the fact that the energies of the states of the ferroelectric and
  antiferroelectric phases differ insignificantly; therefore, a relatively small external influence
  (pressure or electric field) is sufficient to violate the existing stability and transfer
  piezoceramics from one phase state to another. This fact has a positive effect on the generating
  ability of elements made of the material under study, since when exposed to high pre ssure,
  the electrical resistance of the piezoelectric ceramics decreases significantly, and a
  significant part of the electrical energy can be dissipated in the piezoelectric element itself.

• ELECTROMAGNETIC WAVES POLARIZATION TRANSFORMATION BY PRINTED GRATINGS AT MICROWAVES

  А. О. Kasyanov

  2022-01-31

  Abstract ▼

  The problem of printed gratings application is considered as converters of electromagnetic
  waves polarization and polarizing modulators. Two directions in development of antenna engineering
  are considered in this paper. In each of them the scattering fields control of an antenna
  arrays allows essentially to expand functionalities of radio engineering sets. The first direction is
  the creation of auxiliary depolarizing reflectors for two-mirror reflector antennas and folded
  lenses. In addition, in twist-reflectors based on printed gratings, it is possible to constructively
  realize the necessary phase distributions of the field on their surfaces. Thus, it becomes possible to
  use such twist-reflectors to create phase-correcting twist-reflectors. The second direction is connected
  to application of antenna arrays for a reduction of a radar cross section of the radartracking
  targets. Transformation of a field polarization by an antenna array allows to achieve both
  these purposes. In an aspect of high cost and complexity of arrays experimental researches as a method of the analysis the mathematical simulation is selected. Besides, it is shown that introduction
  of impedance loads in the construction of the re-radiating elements of the printed grating
  opens additional possibilities for controlling the field scattered by it. Thus, twist reflectors with
  improved characteristics can be realized on the basis of microstrip-pin gratings. The given results
  can be used for choosing the most of rational electrodynamic structure geometry variant at decision
  of particular problems by antennas engineering. The possible flat arrays based on printed
  complicated shape elements application area is also discussed and it's shown these arrays are the
  very attractive type for controllable radioelectronic covers designing at microwaves. Some numerical
  results presented prove the possibility of a printed reflectarrays application as smart covers
  microwave modules.

• DIRECTIONAL AND POLARISATION PROPERTIES OF A MICROSTRIP RECONFIGURABLE ANTENNA WITH TUNABLE FREQUENCY AND POLARISATION

  А. А. Vaganova, N.N. Kisel, A.I. Panychev

  2021-07-18

  Abstract ▼

  A reconfigurable antenna is an antenna with parameters that can be varied according to the
  requirements of a particular situation. Under variable parameters we can understand the operating
  frequency range, radiation pattern, polarization, as well as various combinations of these parameters.
  In this paper, we propose the design of a reconfigurable microstrip antenna with tunable
  frequency and polarization, and investigate its radiation pattern and polarisation properties. The
  antenna has compact dimensions and can be used in wireless communication systems operating in
  the 2–7 GHz range. 5 pin diodes are included into the antenna design to change the resonant frequency
  and polarization of the antenna by turning the diodes on and off. The simulation of the
  proposed antenna was performed in the FEKO program and the main parameters of the antenna
  were obtained. The analysis of the simulation results showed that for the lower part of the studied
  frequency range (2.05, 2.45 and 3.7 GHz), the polarization is linear. When operating in the higher
  sub-range (5.4, 5.6 and 5.75 GHz), the antenna is circularly polarized, and the direction of the
  polarisation vector rotation depends on the connection of the diodes. This ability to switch polarization
  to orthogonal at the same frequency allows to perform efficient signal reception in the conditions
  of multipath propagation.