Ultra wideband vortex antenna array design for high capacity radio links

In thispaperthe development principles for calculation and construction of the antenna for «smooth» transmission and reception of multichannel ultra-wideband signals with a given spiral phase front applied in Radio-over-fiber system for the seamless data transmission are discussed. The detail description of the current state of research in this field is presented and deeply analyzed, so finally the new unique solutions are proposed and described in detail.Since the transceiver antenna has a significant effect on the signal shape working as a spatio-temporal filter, then the phase of the emitted wave (spin-orbital state) depends only on the antenna geometry. So the inverse problem of the antenna theory should be solved, when the antenna array configuration is synthesized on the basis of the given aperture.The antenna is considered as distributed in-space volume antenna arraybased on tripoles, providing the reception of a «tangled» signal with wave division and spin-orbital state multiplexing. The antenna is calculated using a mathematical and computer modelling and characterized with stable characteristics in the ultra-wide frequency band.This work is supported by the Ministry of Education and Science of Russian Federation under the Basic part of the State assignment for higher education organizations and Scholarship of the President of Russian Federation for young scientists and PhD students who carry out perspective researches in the priority modernization areas of the Russian economy

Tritium concentration in tungsten surface exposed to low-energy, high-flux D plasma

The limits on tritium inventory in the vacuum vessel and the need for prevention of impurity ingress into plasma make plasma-surface interaction on tungsten an important issue. It is well known that plasma exposure on tungsten makes some kinds of blisters on the surface and increases the hydrogen inventory. O n the other hands, there is a possibility that plasma exposure would change the characteristic of surface and surface region in tungsten and cause the increase of tritium inventory. To understand the change of tritium inventory in the surface region and surface in tungsten by plasma exposure, tritium concentration in tungsten exposure by low-energy (3 8eV), high-flux D plasma with was examined with BIXS after thermal exposure of tritium gas. D plasma exposure was carried out at specimen temperature around 495 and 550K. After that, specimens were exposed to gaseous tritium diluted with deuterium at 473K for 3 hours. The tritium concentration was measured with BIXS. The tritium concentration in surface and surface region was found to be increased by plasma exposure. And its concentration of tungsten exposed at 495K was estimated to be twice higher than that of as-received tungsten

Microstrip antenna design for arrays generating OAM mm-wave radio signals

The paper is devoted to development of the single antenna as an element of the array, intended for radiating electromagnetic fields with different orders of the orbital angular momentum (OAM) in the band 77 ÷ 78.5 GHz. Multiplexing on OAM provides more opportunities for safe data transmission and increases the quantity of the simultaneously transmitted channels. The antenna design takes into account the special requirements for its structure, imposed by its practical usage in array. The modeling process includes calculating the dimensions, selecting the suitable materials (Rogers RO 3003) and components, simulating with the software and analyzing the following characteristics: VSWR, return loss S11, input impedance, and radiation pattern. The designed antenna represents a half-wave dipole, fed by coplanar waveguide port and matched to 50 Ohm impedance. Its VSWR is less than 1.8, radiation pattern is quite wide. Its configuration and size provide easy combination of such elements in array, including the question of the feeding lines simplicity. The recommendations on the following research steps are given. The application areas are described.This work is supported by the scholarship of the President of Russian Federation for young scientists and PhD students who carry out perspective researches in the priority modernization areas of the Russian economy

Radon and ionosphere monitoring as a means for strong earthquakes forecast

The relation between radon emanation in seismically active regions and variations of the ionosphere parameters is considered. The quasistationary anomalous electric field generated in the near-ground layer of the atmosphere due to radon and metallic aerosols emanation is proposed as the main agent of the seismo-ionospheric coupling mechanism. The effects of the quasistationary electric field penetrated into the ionosphere are considered theoretically and compared with the experimental results. The comparison confirms the proposed conception of the seismo-ionospheric coupling

Technique for reconstructing a surface shape for measuring coordinates

This paper describes a method of projecting interference fringes as one of the most accessible techniques for measuring the coordinates of objects and scenes that can be used when solving inverse problems in dynamic holographic display, where the coordinates need to be measured in order to compute diffraction structures when reconstructing three-dimensional images. A comparative analysis is presented of the experimental results obtained with successive projections of interference patterns with two different periods, using a Mach-Zehnder interferometer in coherent light and a micromirror projector with digital generation of fringes in white light. The use of the method is limited by the size of the objects and scenes. The possibilities of using more refined methods, including the holographic approach to phase reconstruction, are discussed. © 2006 Optical Society of America

An approach for generating and detecting the signals with the given orbital angular momentum for wireless communication systems

The paper is devoted to the development of methods for increasing the efficiency of wireless communication channels via usage of multiplexing by the orbital angular momentum (OAM), which allows to form an additional basis of orthogonal functions for the simultaneous independent transmission of several signals. In particular, the generation process involves the formation of a beam using an antenna array radiating in the 77-78.5 GHz range, the design of which allows to form various orders of the OAM signals without restructuring. The important points in the design process were ensuring the minimum divergence of the beam during the propagation and obtaining the maximum gain. Regarding receiving, a solution was proposed for detecting an OAM signal in case of misalignment between transmitting and receiving antennas. An antenna array consisting of two perpendicular dipoles has been proposed as a receiving device, which allows receiving the OAM signal from any direction. An important point of detection is the preservation of information about the phase of the received signal. The results of calculations and simulation of the transmission and reception in the range of 77-78.5 GHz are shown.This work was supported by the grant of Russian Science Foundation (RSF) (project No. 18-19-00123)