Subjects -> COMMUNICATIONS (Total: 518 journals)
    - COMMUNICATIONS (446 journals)
    - DIGITAL AND WIRELESS COMMUNICATION (31 journals)
    - HUMAN COMMUNICATION (19 journals)
    - MEETINGS AND CONGRESSES (7 journals)
    - RADIO, TELEVISION AND CABLE (15 journals)

COMMUNICATIONS (446 journals)            First | 1 2 3 | Last

Showing 201 - 400 of 480 Journals sorted alphabetically
Journal of Asian Pacific Communication     Hybrid Journal   (Followers: 5)
Journal of Biocommunication     Open Access  
Journal of Broadcasting & Electronic Media     Hybrid Journal   (Followers: 13)
Journal of Cardiovascular Computed Tomography     Hybrid Journal   (Followers: 2)
Journal of Chinese Writing Systems     Hybrid Journal  
Journal of Communication     Hybrid Journal   (Followers: 62)
Journal of Communication and Innovation NIDA     Open Access  
Journal of Communications Software and Systems     Open Access   (Followers: 1)
Journal of Community Informatics     Open Access   (Followers: 3)
Journal of Computer-Mediated Communication     Open Access   (Followers: 35)
Journal of Development and Communication Studies     Open Access   (Followers: 5)
Journal of Digital Media & Policy     Hybrid Journal   (Followers: 1)
Journal of Environmental Media     Hybrid Journal  
Journal of European Periodical Studies     Open Access   (Followers: 1)
Journal of European Popular Culture     Hybrid Journal   (Followers: 10)
Journal of Graph Theory     Hybrid Journal   (Followers: 6)
Journal of Greek Media & Culture     Hybrid Journal   (Followers: 3)
Journal of Information and Organizational Sciences     Open Access   (Followers: 1)
Journal of Information and Telecommunication     Open Access   (Followers: 2)
Journal of Information, Communication and Ethics in Society     Hybrid Journal   (Followers: 22)
Journal of Interactional Research in Communication Disorders     Hybrid Journal   (Followers: 4)
Journal of Interdisciplinary Voice Studies     Hybrid Journal  
Journal of International and Intercultural Communication     Hybrid Journal   (Followers: 19)
Journal of International Communication     Hybrid Journal   (Followers: 3)
Journal of Islamic Manuscripts     Hybrid Journal   (Followers: 8)
Journal of Italian Cinema and Media Studies     Hybrid Journal   (Followers: 5)
Journal of Language and Politics     Hybrid Journal   (Followers: 5)
Journal of Language and Sexuality     Hybrid Journal   (Followers: 1)
Journal of Location Based Services     Hybrid Journal   (Followers: 3)
Journal of Magnetic Resonance Imaging     Hybrid Journal   (Followers: 16)
Journal of Media and Communication Studies     Open Access   (Followers: 26)
Journal of Media Business Studies     Hybrid Journal   (Followers: 3)
Journal of Media Ethics : Exploring Questions of Media Morality     Hybrid Journal   (Followers: 14)
Journal of Media Innovations     Open Access   (Followers: 3)
Journal of Media Literacy Education     Open Access   (Followers: 2)
Journal of Media Psychology     Hybrid Journal   (Followers: 19)
Journal of Medical Internet Research     Open Access   (Followers: 23)
Journal of Modern Periodical Studies     Full-text available via subscription  
Journal of Organizational Knowledge Communication     Open Access   (Followers: 2)
Journal of Professional Communication     Open Access   (Followers: 5)
Journal of Public Interest Communications     Open Access   (Followers: 1)
Journal of Radio & Audio Media     Hybrid Journal   (Followers: 7)
Journal of Radiology Nursing     Hybrid Journal   (Followers: 4)
Journal of Radiotherapy in Practice     Hybrid Journal   (Followers: 8)
Journal of Science & Popular Culture     Hybrid Journal   (Followers: 1)
Journal of Science Communication     Open Access   (Followers: 15)
Journal of Selcuk Communication     Open Access  
Journal of Technical Writing and Communication     Full-text available via subscription   (Followers: 10)
Journal of the American College of Radiology     Hybrid Journal   (Followers: 13)
Journal of the Association for Information Systems     Open Access   (Followers: 29)
Journal of Writing in Creative Practice     Hybrid Journal   (Followers: 12)
Journalism & Mass Communication Educator     Hybrid Journal   (Followers: 21)
Journalism & Communication Monographs     Hybrid Journal   (Followers: 19)
Journalism & Mass Communication Quarterly     Hybrid Journal   (Followers: 27)
Journalism Research     Open Access   (Followers: 4)
Journalistica - Tidsskrift for forskning i journalistik     Open Access   (Followers: 1)
Jurnal Aspikom : Jurnal Ilmu Komunikasi     Open Access  
Jurnal Dakwah dan Komunikasi     Open Access  
Jurnal Dakwah Risalah     Open Access  
Jurnal Ilmu Komunikasi     Open Access  
Jurnal Media dan Komunikasi Indonesia     Open Access   (Followers: 3)
Jurnal MEKOM (Media Komunikasi Pendidikan Kejuruan)     Open Access  
Jurnal Representamen     Open Access  
Jurnal Simbolika : Research and Learning in Communication Study     Open Access  
Kaleidoscope : A Graduate Journal of Qualitative Communication Research     Open Access   (Followers: 3)
Komunika     Open Access  
Komuniti : Jurnal Komunikasi dan Teknologi Informasi     Open Access  
La Mirada de Telemo     Open Access  
La Tercera Orilla     Open Access  
La Trama de la Comunicación     Open Access   (Followers: 1)
Language and Dialogue     Hybrid Journal   (Followers: 1)
Language and Speech     Hybrid Journal   (Followers: 18)
Language Problems & Language Planning     Hybrid Journal   (Followers: 2)
Language, Interaction and Acquisition     Hybrid Journal   (Followers: 3)
Lingue e culture dei media     Open Access  
Llengua, societat i comunicació     Open Access  
Logos : Comunicação e Universidade     Open Access  
Lumina     Open Access  
Magnetic Resonance Imaging     Hybrid Journal   (Followers: 9)
Magnetic Resonance Materials in Physics, Biology and Medicine     Hybrid Journal   (Followers: 3)
MATRIZes : Revista do Programa de Pós-Graduação em Comunicação da Universidade de São Paulo     Open Access   (Followers: 1)
McMaster Journal of Communication     Open Access   (Followers: 1)
Medea     Open Access  
Media & Jornalismo     Open Access  
Media & Viestintä     Open Access  
Media and Communication     Open Access   (Followers: 14)
Media International Australia     Hybrid Journal   (Followers: 3)
Mediaciones     Open Access  
Mediaciones Sociales     Open Access  
MediaTropes     Open Access   (Followers: 3)
Medical Writing     Hybrid Journal   (Followers: 4)
MedieKultur. Journal of media and communication research     Open Access   (Followers: 12)
Mediterranea : International Journal on the Transfer of Knowledge     Open Access  
MEDIUM (Jurnal Ilmiah Fakultas Ilmu Komunikasi Universitas Islam Riau)     Open Access  
Metaphor and the Social World     Hybrid Journal   (Followers: 2)
Metaverse Creativity     Hybrid Journal   (Followers: 6)
Middle East Journal of Culture and Communication     Hybrid Journal   (Followers: 5)
Middle East Media Educator     Open Access   (Followers: 2)
Moment Dergi     Open Access  
Myth & Symbol     Hybrid Journal   (Followers: 9)
Narrative Culture     Full-text available via subscription   (Followers: 4)
NAUS : Revista Lusófona de Estudos Culturais e Comunicacionais     Open Access   (Followers: 1)
Netcom     Open Access  
Neuroimaging Clinics of North America     Full-text available via subscription   (Followers: 4)
New Media and Mass Communication     Open Access   (Followers: 31)
New Review of Film and Television Studies     Hybrid Journal   (Followers: 24)
Nonprofit Communications Report     Hybrid Journal   (Followers: 3)
Nordic Journal of Media Management     Open Access   (Followers: 1)
Nordic Journal of Media Studies     Open Access   (Followers: 1)
Nordicom Review     Open Access   (Followers: 3)
Norsk medietidsskrift     Open Access  
Northern Lights     Hybrid Journal   (Followers: 2)
Novos Olhares : Revista de Estudos Sobre Práticas de Recepção a Produtos Midiáticos     Open Access  
Nueva Revista del Pacífico     Open Access  
Obra Digital     Open Access  
Observatorio (OBS*)     Open Access  
Oficios Terrestres     Open Access  
Open Medical Informatics Journal     Open Access  
Openings : Studies in Book Art     Open Access   (Followers: 9)
Organicom     Open Access  
Pacific Asia Journal of the Association for Information Systems     Open Access   (Followers: 3)
PAJ: A Journal of Performance and Art     Hybrid Journal   (Followers: 15)
Palabra Clave     Open Access   (Followers: 1)
Passagens     Open Access  
Pediatric Radiology     Hybrid Journal   (Followers: 7)
Performing Islam     Hybrid Journal   (Followers: 3)
Pixel-Bit. Revista de Medios y Educacion     Open Access  
Porn Studies     Hybrid Journal   (Followers: 6)
post(s)     Open Access  
Pozo de Letras     Open Access  
Pragmatics and Society     Hybrid Journal   (Followers: 12)
PragMATIZES : Latin American Journal of Cultural Studies     Open Access   (Followers: 1)
PRISMA.COM     Open Access  
Proceedings of the American Society for Information Science and Technology     Hybrid Journal   (Followers: 26)
Profetik : Jurnal Komunikasi     Open Access  
Public Journal of Semiotics     Open Access   (Followers: 1)
Public Relations Review     Hybrid Journal   (Followers: 16)
Publicitas : Comunicación y Cultura     Open Access  
Punto Cero     Open Access  
Quaderni     Open Access  
Qualitative Research Reports in Communication     Hybrid Journal   (Followers: 10)
Qualitative Studies     Open Access   (Followers: 12)
Quality and User Experience     Hybrid Journal   (Followers: 2)
Quantitative Science Studies     Open Access   (Followers: 1)
Quarterly Journal of Speech     Hybrid Journal   (Followers: 15)
Quarterly Review of Film and Video     Hybrid Journal   (Followers: 20)
Queer Studies in Media & Popular Culture     Hybrid Journal   (Followers: 4)
Question     Open Access  
Questions de communication     Open Access  
Questões Transversais - Revista de Epistemologias da Comunicação     Open Access  
Radio Journal : International Studies in Broadcast & Audio Media     Hybrid Journal   (Followers: 5)
Radioelectronics and Communications Systems     Hybrid Journal   (Followers: 1)
REDD : Revista de estudios del discurso digital     Open Access  
Res Rhetorica     Open Access   (Followers: 1)
Research Journal of Information Technology     Open Access   (Followers: 2)
Research on Education and Media     Open Access  
Review of Cognitive Linguistics     Hybrid Journal   (Followers: 6)
Revista Competência     Open Access  
Revista Compolítica     Open Access  
Revista Contracampo     Open Access  
Revista de Comunicación y Salud     Open Access  
Revista ECO-Pós     Open Access  
Revista Eletrônica de Comunicação, Informação & Inovação em Saúde     Open Access  
Revista ICONO14. Revista científica de Comunicación y Tecnologías emergentes     Open Access  
Revista Latina de Comunicacion Social     Open Access   (Followers: 1)
Revista Mediação     Open Access  
Revista Mexicana de Opinión Pública     Open Access  
Revista Nexus Comunicación     Open Access  
Revista Observatório     Open Access  
Revista Panorama : Revista de Comunicação Social     Open Access  
Revista UNINTER de Comunicação     Open Access  
Revue de recherches en littératie médiatique multimodale     Open Access  
Revue française des sciences de l’information et de la communication     Open Access   (Followers: 1)
RIHC : Revista Internacional de Historia de la Comunicación     Open Access  
Russian Journal of Communication     Hybrid Journal  
RUTA Comunicación     Open Access  
Schermi. Storie e culture del cinema e dei media in Italia     Open Access  
Science China Information Sciences     Hybrid Journal   (Followers: 1)
Scientific Bulletin     Open Access  
Screen     Hybrid Journal   (Followers: 17)
Seminars in Interventional Radiology     Hybrid Journal   (Followers: 7)
Semiotika     Open Access  
Sensorium Journal     Open Access  
Seton Hall Journal of Sports and Entertainment Law     Open Access   (Followers: 3)
Sexualization, Media, & Society     Open Access   (Followers: 3)
SIGDOC Communication Design Quarterly     Full-text available via subscription  
Sign Language & Linguistics     Hybrid Journal   (Followers: 1)
Sign Language Studies     Full-text available via subscription   (Followers: 3)
Sign Systems Studies     Open Access  
Signo y Pensamiento     Open Access  
Signs & Media : A Journal of Semiotics in China and the World     Open Access  
Social Communication     Open Access   (Followers: 2)
Social Imaginaries     Full-text available via subscription   (Followers: 1)
Social Interaction : Video-Based Studies of Human Sociality     Open Access   (Followers: 1)
Social Networking     Open Access   (Followers: 3)
Sociologia della Comunicazione     Full-text available via subscription   (Followers: 1)
Solid State Nuclear Magnetic Resonance     Hybrid Journal   (Followers: 3)
Sound Studies : An Interdisciplinary Journal     Hybrid Journal  
South African Journal of Communication Disorders     Open Access   (Followers: 1)
Speech, Language and Hearing     Hybrid Journal   (Followers: 12)

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Similar Journals
Journal Cover
Radioelectronics and Communications Systems
Journal Prestige (SJR): 0.198
Number of Followers: 1  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0735-2727 - ISSN (Online) 1934-8061
Published by Springer-Verlag Homepage  [2469 journals]
  • Heterogeneous Performance Assessment of New Approach for
           Partially-Correlated χ2-Targets Adaptive Detection

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      Abstract: Radars are the cornerstones of modern integrated air defense systems. The decision on the present or absence of object, ensuring non-fluctuating false alarms, represents one of its fundamental concepts. This involves the implementation of constant false alarm rate (CFAR) strategy that updates the detection threshold in accordance with the inhomogeneous observation scenario. The hardness of finding a single CFAR variant, to deal with diverse noise situations, necessitates the development of composite technique. In this regard, fusion of particular decisions of single CFAR schemes provides better final detection through appropriate fusion rules. This paper is intended with the analysis of linear fusion (LF) of CA, OS, and TM structures. The target of interest and the fallacious ones are supposed to follow χ2-model with two-degrees of freedom in their fluctuation. The closed-form expression is derived for the detection performance. Our simulation results demonstrate that the LF model exhibits robust behavior on the presence or absence of interferers. Additionally, the LF ideal performance surpasses the Neyman–Pearson (N-P) detector one, which is the yardstick of the CFAR world. Moreover, the LF strategy has the capability to hold the unchanged false alarm rate in face of the presence of interferers.
      PubDate: 2021-12-01
      DOI: 10.3103/S0735272721120025
       
  • Complexity of I and Q Signals in OFDM and Method of Simpler Decoding and
           Error Detection

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      Abstract: The modulation schemes in the IEEE 802.11 radio frequency communication protocols are based on two carriers at right angles, called I and Q signals. These two signals, which are formed for the data symbols, are further modulated at radio frequency on two main carriers, which have a phase shift of 90° to each other. The critical analysis of the methods for generating the I/Q signals is given here. The phase and amplitude imbalance errors caused by using two signals to decode one data element are shown. This scheme is used mainly together with the orthogonal frequency division multiplexing (OFDM), employing the Inverse Fourier Transform (IFFT) at the transmitter and direct Fast Fourier Transform (FFT) at the receiver. An alternative better method is described, which does not need to use IFFT and FFT. This method involves the sequential demodulation of subcarriers one by one, and finally the error prone subcarriers are ascertained. It is also feasible to employ this method for correcting the symbol errors.
      PubDate: 2021-12-01
      DOI: 10.3103/S0735272721120037
       
  • Miniaturization and Optimization of FR4 Based CPW-fed Antenna for
           Multiband Applications

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      Abstract: A unique miniaturized and optimized Multiband coplanar waveguide (CPW-fed) antenna for modern wireless communication is presented. A new technique of using a Modified Ground Structure (MGS) and Frequency Shifting Strips (FSS), along with Defected Ground Structure (DGS) and Metamaterial (MTM) loading have been employed in the design to achieve the Multi-frequency operation. The proposed antenna generates four separate impedance bandwidths and covers the minimum required frequency bands of GSM 1800/1900, Wi-Fi/WLAN 5.2/5.5 GHz and WiMAX 3.3/10.3 GHz. The antenna is relatively small in size 17×20 mm2 and operates over the frequency ranges of 1.45–2.08, 2.87–3.44, 5.01–5.58, and 8.89–10.69 GHz. The designed antenna was simulated using the Ansoft HFSS, a FEM-based simulator. This paper presents the simulated characteristics of antenna including the reflection coefficient, gain, radiation efficiency, radiation pattern, impedance bandwidth, VSWR, the surface current and electric field distributions. Antenna’s key structural parameters and their effects on the antenna performance were also studied.
      PubDate: 2021-12-01
      DOI: 10.3103/S0735272721120049
       
  • Simulation of Raman Amplifier Using TrueWave RS Active Fiber with Uniform
           Bandwidth in C+L Telecommunication Windows

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      Abstract: The paper presents the simulation results of a broadband fiber Raman amplifier with uniform gain band covering C+L telecommunication windows in the standard TrueWave RS fiber. Main advantages of the fiber amplifier with active medium based on the single-mode TrueWave RS type fiber were analyzed by comparing this amplifier with the erbium doped fiber amplifier. A simplified model for the analytical description of the ultrawideband fiber Raman amplifier with multiwave pumping has been proposed. In this study, the problem of simulating the uniform bandwidth of working frequencies of fiber Raman amplifier in (C+L)-band telecommunication windows is solved in two stages: first, we obtain an almost exact analytical approximation of the Raman gain profile in the frequency region of Stokes shift above 20 THz that at the second stage significantly simplifies the gain band equalization in configuration with multiple pumping wavelengths. It has been shown that the gain ripple can be dramatically reduced from more than 3 to 0.2 dB by increasing the number of pumping sources M from M = 2 to M = 6, however, further increase of M has almost no effect on the improvement of gain band irregularity.
      PubDate: 2021-12-01
      DOI: 10.3103/S0735272721120013
       
  • Analysis of Interference Alignment Based Multi-User MIMO Precoding

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      Abstract: Interference mitigation for better system performance is highly significant in the modern communication systems. Rising day to day demand for wireless communication has introduced some new research efforts in terms of spectrum efficiency, maximum possible user rates, and the reuse of frequency spectrum and minimum level of interference. Interference alignment (IA) is a novel way to mitigate the inter-cell interference (ICI) of a network that leads to a better system performance. One effective technique behind this scheme is to align the interfering signal from each transmitter of neighboring cell into a predefined direction, and obtain the receive antenna combining vector of each user. With the perfect channel state information and having a feedback system with the cell base station transmitter, the IA system can increase the system sum-rate. Increasing the cell edge spectral efficiency in the cellular system is one of the prime performance factors. This paper is based on the cell edge users of a cellular communication system. Scheduling techniques for the selection of best users and antennas from large groups of users and antennas, respectively, are used in this paper. This article deals with a precoder design, with antenna and user selection techniques based on partial IA in two-cell and three-cell networks of a downlink MU-MIMO system. A comparative analysis was made on the system performance by using the singular value decomposition (SVD) based precoding and geometric mean decomposition (GMD) based precoding techniques. In this study the LTE codebook is used, which is known both to the transmitter and the receiver.
      PubDate: 2021-11-01
      DOI: 10.3103/S0735272721110054
       
  • Protection of Coherent Pulse Radars against Combined Interferences. 2.
           Analysis of Influence of Decorrelating Factors on Efficiency of Adaptive
           Sequential STSP

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      Abstract: This is the second paper in a series of articles devoted to modern methods of protection of coherent-pulse radars against the combined interference (i.e., an additive mixture of internal noise, masking clutter and noise jamming). Quantitative analysis of the influence of decorrelating factors on the efficiency of sequential adaptive systems with separate space-time signal processing (STSP) against the background of combined interference has been performed under conditions when the spatial processing with noise jamming compensation precedes the inter-period processing with clutter compensation. The analysis-based values of energy losses during the fluctuations of the random estimate of the spatial processing weight vector obtained for each sounding period over the limited size classified sample of noise jamming confirm the need to fix (store) this vector for the period of the inter-period clutter compensation. It is shown that the additional lack of classification of the training sample of interference increases the energy losses.
      PubDate: 2021-11-01
      DOI: 10.3103/S0735272721110017
       
  • Wideband X-band Multilayer Reflectarray on Thin Dielectric Substrates

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      Abstract: The simulation and measurement results of characteristics of the X-band offset reflectarray with the diameter of 460 mm on thin dielectric substrates are presented. The optimization of array main characteristics is performed using electrodynamic simulation by the full-wave method. The experimentally measured antenna characteristics are as follows: the gain is of 27.7 dB, the –3 dB main-lobe beamwidth at the frequency of 9.6 GHz is equal to 4° and 4.5° in the E- and H-planes, respectively. The operating frequency band at the –1 dB gain level is equal to 8.9–10 GHz.
      PubDate: 2021-11-01
      DOI: 10.3103/S0735272721110029
       
  • Method for Reduction of Speech Signal Autoregression Model for Speech
           Transmission Systems on Low-Speed Communication Channels

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      Abstract: In this paper it is considered the problem of reduction or reduction of the order p ≫ 1 of an autoregressive model (AR-model) of a speech signal by the criterion of minimum loss of useful information. The problem is formulated as an optimization problem in terms of discrete spectral modeling. It is indicated that the most acute problem in solving is the necessity to scale the AR-model parameters for the simulated signal at each step of iterative calculation process. To overcome this problem, it is proposed to use the measure of information divergence of signals in the frequency domain with the property of scale invariance as the goal functional. On its basis, a new method of the AR-model reduction is developed where the scaling operation exceeds the limits of the iterative optimization procedure. The effectiveness of the proposed method is substantiated theoretically and researched experimentally. It is shown that the main component of the achieved effect is the gain in accuracy of the reduced AR-model in the Kullback–Leibler information metric. The results obtained are addressed to researchers and developers of systems and technologies for digital speech transmission over low-speed communication channels.
      PubDate: 2021-11-01
      DOI: 10.3103/S0735272721110030
       
  • Approximation Method for Investigating Acousto-Optic Delay Line
           Characteristics

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      Abstract: This paper has displayed high potential capabilities of the acousto-optic delay line (AODL) in processing the wideband analog signals. The actuality of the development of the theory of physical processes in AODL suitable for practical applications is substantiated. An approximating method for solving this problem is proposed. It was shown that the use of piecewise-linear approximation made the calculation of the time and frequency characteristics of AODL much easier. Universal formulas were derived for determining the AODL output response, its duration and the rise time at different ratios of the input pulse duration and the time of the elastic wave packet crossing the laser beam. The method and formulas are proposed for determining the AODL cutoff frequency. The numerical simulation of the proposed formulas was performed and their adequacy proved. The paper discusses the possible use of obtained formulas for investigating the AODL characteristics beyond the cutoff frequency. The established patterns and the numerical analysis results were experimentally approbated using the mockup of AODL with direct detection. The oscillogram of input and output pulses obtained at different ratios of the input pulse duration to the time of the elastic wave packet crossing the laser beam are discussed in the context of established patterns and the numerical analysis results. The cutoff frequency was determined by using the normalized experimental graph plot of AODL amplitude frequency characteristic, and it was shown that the obtained cutoff frequency was in good correspondence with the numerical analysis results.
      PubDate: 2021-11-01
      DOI: 10.3103/S0735272721110042
       
  • Sparseness of Natural Oscillations Spectrum for Double-Mirror Open
           Resonator Using Mode-Selective Scatterers on One of Mirrors Surface

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      Abstract: The effective procedure for spectrum sparseness of natural oscillations of double-mirror open resonators (OR) is proposed. It is based on the placement of scatterers with a specially determined geometric profile on one of the mirrors surface, forming the single mode-selective reflector. This procedure is used to synthesize two profiles of these scatterers for OR with flat and cylindrical mirrors. We propose the rectangular metal bar and the echelette-corner reflector with three rectangular steps symmetric to the plane of resonator symmetry. These scatterers placed on the flat OR mirror provide a minimal effect on the spatial-frequency characteristics of the operating natural oscillation, and significantly reduce the Q-factor of most of the rest oscillations. The spectral characteristics of the OR with these inserts are calculated for excitation by the current source and the eigen mode of a supply waveguide. The possibility of significant decrease in the number of OR natural oscillations is shown, in comparison with the resonator without these scatterers. The effect of increasing the radiation Q-factor of operating oscillation is observed using the echelette-corner scatterer. The technique used to determine the scatterers geometric profile is suitable for spectrum sparseness of the OR of arbitrary dimensions with mirrors of any shapes.
      PubDate: 2021-10-01
      DOI: 10.3103/S0735272721100010
       
  • Optimization of Parameters of Adders and Barrel Shifter Based on Emerging
           QCA Technology

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      Abstract: Compared to metal-oxide-semiconductor field-effect transistors (MOS), the quantum-dot cellular automata (QCA) offer great advantages. This paper deals with the QCA implementation of digital circuits such as full adder, multiplexer, carry-save adder, carry-select adder, carry-skip adder, and barrel shifter for robust architecture in the nanoelectronics domain. The goal is to provide a framework for optimizing QCA designs utilizing coplanar cells that is also flexible enough to be used in complicated system design. As a result of this synthesis, the new design is appropriate for the creation of nanoelectronic circuits. The QCADesigner tool was used to verify the digital circuits in the synthesized designs presented in this article. The QCA simulation environment is used to verify designs, extract parameters, and perform digital computing. The primary goal of this study is to develop a robust adder design in terms of bounded box area and other cost primitives. The coplanar method is used to construct the QCA layouts of various adders, which is more efficient and compact. The comparison results have shown that the adoption of novel digital designs offers better results and provides a more robust architecture as compared to the literature works.
      PubDate: 2021-10-01
      DOI: 10.3103/S0735272721100022
       
  • Design of Pseudo-Random Discrete Signals with Fractional Power-Law Angular
           Modulation

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      Abstract: The design approach of pseudo-random discrete signals with fractional power-law angular modulation (FM/PM) is considered in the article. These signals as a discrete set of time values with the uniform sample spacing acquire the properties of pseudo-random sequences. The envelope and phase are defined for the constructed signals using the analytical signal concept. It is found that the time discretization of the oscillation representation by the product of two functions, using the WKB-approximation (Wentzel–Kramers–Brillouin) to solve the parametric oscillator equation, violates the condition of its frequency change slowness (physical feasibility of the solution). The appearance mechanism of pseudo-random behavior of discrete signals with the fractional power-law FM/PM is based on the properties of algebraic irrational numbers sequences. The ambiguity and autocorrelation functions of the Fourier spectra of the designed signals are investigated. The designed signals stealthiness is considered, from the point of view of their disguising as noise, based on the calculation of nonparametric BDS statistics (Brock–Dechert–Scheinkman). The BDS statistics values for different durations of the designed signals are estimated. The method to increase the designed signals stealthiness is proposed.
      PubDate: 2021-10-01
      DOI: 10.3103/S0735272721100034
       
  • Entropic Analysis of Distributed Generation Systems

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      Abstract: It is proposed to use the entropy divergence function for entropy analysis of distributed generation systems. A description of the system of distributed generation through the distribution of carriers and resources of generation and consumption is represented. A new method for calculating the probabilities of micro- and macrostates of the system is given. The function of entropy divergence is obtained as an integral characteristic of the macrostate of the distributed generation system, as well as its main properties. The entropic divergence of the solar radiation flux is calculated. The Matlab R2020a Simulink® software environment simulates a distributed generation system consisting of a renewable energy source, a storage device, and an active load. There are represented the time dependences of the storage device charge state modification. The entropy and entropy divergence of the energy flow at the storage device output in such system are calculated. It is shown that to reduce the value of entropy divergence of energy flow at the storage device output, i.e. to bring its operation mode to the maximum allowable, it is necessary in accordance with the entropy divergence of solar radiation flux, taken with the opposite sign, to change the storage capacity without increasing its absolute value. This reduces the duration of the time intervals when the storage device is fully charged and fully discharged, but the energy balance in the system is maintained.
      PubDate: 2021-10-01
      DOI: 10.3103/S0735272721100046
       
  • Adaptive Digital Modem for Tropospheric Scatter Link with Two Different
           Communication Stations

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      Abstract: The joint operation of two troposcatter digital stations (TSDS) of different modifications can be implemented quickly through an adaptive signal control in stations at the same time. Such control can be organized with the help of an adaptive simulation algorithm for tropospheric scatter link (TSL) by using TSDS1,2 and controlling the signals at the output and input of adaptive antennas (AdA), adaptive transmitters (AdT), and adaptive receivers (AdR) in each station. We used a modern digital troposcatter modem (DTM) of one station and adaptive signal processing based on a digital special-purpose control unit (DSCU) of another station. As a result, the adaptive signal control stabilizes the levels of tropospheric signals in both stations at the same time, which provides the regular information reliability of TSL with TSDS of different modifications in their joint work.
      PubDate: 2021-09-01
      DOI: 10.3103/S0735272721090065
       
  • Synthesis of Plane Waveguide Arrays Taking into Account Mutual Coupling of
           Radiators

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      Abstract: The variational approach is used for solving the synthesis problem of plane rectangular array with waveguide excitation of its elements. The proposed functional includes three components that allow us to minimize the mean square deviation of the given and synthesized amplitude radiation patterns (RP), the value of the field amplitude in the given near zone regions, and the norm of excitation coefficients of the array elements. The mutual coupling of separate array radiators is taken into account solving the corresponding electrodynamic problem. The Hallen’s integral equation is used to determinate the current distribution in the array radiators. The optimal excitation coefficients of the radiators are determined minimizing the proposed functional, it is reduced to solving the nonlinear Euler integral equations system, since the amplitude radiation characteristics are the input data of the problem. The resulting system of nonlinear integral equations is solved efficiently by the method of successive approximations; the relaxation is its characteristic feature. The calculation results show that the developed approach can be used for arrays with different configurations, in particular with hexagonal placement of radiators.
      PubDate: 2021-09-01
      DOI: 10.3103/S0735272721090028
       
  • Optimal Designs of X-Band Waveguide Stepped-Thickness Septum Polarizer

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      Abstract: This article presents results of optimization and development of X-band square waveguide stepped-thickness septum polarizers. Electromagnetic characteristics of the polarizers were simulated and optimized numerically using finite elements method. Optimal dimensions of the 2-, 3-, and 4-section stepped-thickness septum polarizers for various fractional bandwidths have been obtained. It is demonstrated that application of the stepped-thickness septum with 3 sections instead of it constant-thickness counterpart improves return loss and cross-polarization discrimination of the septum polarizer by 2–6 dB and 3–6 dB respectively, depending on fractional bandwidth. A prototype of the optimal waveguide polarizer with 3-section stepped-thickness septum configuration for the operating frequency range 7.70–8.50 GHz was developed, manufactured and tested. Measured values of VSWR and cross-polar discrimination of the prototype together with necessary transitions and bends within the stated above frequency range are less than 1.4 and higher than 30 dB, respectively. The developed compact stepped-thickness septum polarizer is a good candidate to be applied in the quasi-monopulse dual-circular polarization feed system of the ground station reflector antenna for tracking earth observing satellites.
      PubDate: 2021-09-01
      DOI: 10.3103/S0735272721090041
       
  • Investigation and Tuning Procedure of Ka-Band Phased Antenna Array

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      Abstract: The parameters of elements of the structural diagram of the Ka-band phased antenna array have been analyzed including the analog ferrite and discrete semiconductor phase shifters, control unit and the power distribution system. A technique for tuning the array phasing elements is proposed, the use of which makes it possible to materially simplify and reduce the costs of their production. The effectiveness of the proposed tuning method has been tested experimentally using an example of 9-element linear phased antenna array that allows us to check an assumption about the nonidentity of phase characteristics of elements in antenna channels and their impact on parameters of the radiation pattern (RP). The tuning technique also takes into account the impact of electric characteristics of the aerial fairing or airborne radome, if present. The essence of the technique implies that all radiating elements of antenna, except the central channel, where a phase shifter is not present, are covered with radio absorbing material. Next, the radiation pattern maximum is oriented in the direction of the radiating element located in the far zone by selecting the type and value of control signals. The determined control signal is stored in memory. Next, by opening the apertures of other radiator elements and tuning them one by one, we obtain a control signal matrix for the specified scanning sector. Thus, the phase shifter control matrix is formed, and additional computing devices are not needed during scanning. As a result of conducted experimental investigations based on an example of 9-element linear phased antenna array and using the proposed technique, it has been shown that the lack of identity of parameters of microwave elements does not affect in any way the speed and accuracy of the phase distribution formed in the antenna aperture.
      PubDate: 2021-09-01
      DOI: 10.3103/S0735272721090053
       
  • Estimation of Statistical Characteristics of Antenna Arrays with Axial
           Symmetry under Condition of Small Phase Errors

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      Abstract: The method for estimating statistical characteristics of radiation field, amplitude-phase distribution, and correlation function of phase errors of arbitrary aperture antennas is presented. It is convenient for analyzing the statistics of antenna arrays with axial symmetry. The main mean and fluctuation characteristics within the direct external problem of statistical antenna theory are determined on the example of cylindrical circular antenna array. The estimation of the mean power radiation pattern, main lobe direction fluctuation of array, and comparison with the known results are carried out. We show that according to the estimated statistical characteristics, circular cylindrical arrays occupy an intermediate position between linear and circular ones.
      PubDate: 2021-09-01
      DOI: 10.3103/S0735272721090016
       
  • Antenna Array and Feed-Backward Equalizer as Single Adaptive Device

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      Abstract: This paper considers an adaptive antenna array (AAA) with its weight factors combined with those of Feed-Forward (FF) part of a channel equalizer, while the array output signal is combined with that of Feed-Backward (FB) part of the equalizer. Such an array and distributed equalizer operate as a single multichannel adaptive filter providing the possibility of receiving a useful signal under conditions of its multipathing and in the presence of signals of external interference sources. The paper presents the architecture of antenna array/equalizer and the mathematical description of its multichannel adaptive algorithms, such as recursive least-squares (RLS) algorithm based on the Matrix Inversion Lemma (MIL), QR-decomposition and Householder’s transformation with quadratic computational complexity, and also simple algorithms based on the least squares (LS) criterion, normalized LS (NLS) and affine projection (AP) algorithms with linear computational complexity. The simulation results of the linear antenna array with eight antennas/channels, which receives a useful 16-PSK signal having passed through a two-ray communication channel in the presence of one to four interference sources with signal-to-interference ratio (SIR) of –30 dB for each interference and the signal-to-noise ratio (SNR) of 10–30 dB in the array channels, demonstrate the efficiency of the solution proposed.
      PubDate: 2021-09-01
      DOI: 10.3103/S073527272109003X
       
  • Compact CPW-fed Multiband Antenna for 5G Communication

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      Abstract: This paper proposes a coplanar waveguide fed multiband antenna for Wi-Fi and 5G networking applications. To obtain the desired frequencies, this proposed work used an innovative method consisting of frequency shifting strips (FSS) and a U-slot. The ANSYS HFSS software, a FEM-based electromagnetic field solver, is used to simulate the designed antenna. This planned antenna covers the 5G frequency bands of 28, 35, and 37 GHz, with a maximum gain of 11.61 dB and radiation efficiency of 92%. In the result analysis section, the simulated results are compared to the measured results to check the efficiency of the simulated design. This paper also includes a comparison of the proposed antenna performance with that of other existing antennas. This paper also includes information on antenna gain, VSWR, field distributions, bandwidth, and surface current distributions (both E and H field) about the designed antenna.
      PubDate: 2021-08-01
      DOI: 10.3103/S0735272721080057
       
 
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