APPLICATION OF PLASMA ANTENNA TECHNOLOGY TO IMPROVE RADIO COMMUNICATION STEALTH IN VHF BAND

Рассматривается плазменная вибраторная антенна, которая предназначена для работы в VHF диапазоне на частоте 140 МГц. Вибраторные плазменные антенны отличаются от обычных вибраторных антенн тем, что металлический проводник заменяется плазмой в газоразрядной трубке. Плазменный вибратор, создаваемый разрядом в трубке, способен включаться и выключаться за время порядка микросекунд. Применение плазменной антенны позволяет обеспечить два режима работы: активный, когда плазма индуцирует проводящую поверхность, и скрытый, когда антенна становится практически невидимой для электромагнитных волн, а плазменное облако отсутствует. Для определения характеристик антенны использовалось электродинамическое моделирование. Полученные результаты показывают, что характеристики плазменной вибраторной антенны близки к характеристикам эквивалентного ей металлического диполя, при этом длина плазменной антенны меньше. Для определения эффективности скрытного режима антенны производилось сравнение характеристик эффективной площади рассеяния плазменной антенны с выключенным плазменным облаком и эквивалентного металлического диполя. Полученные результаты показывают, что плазменная антенна обладает высокой эффективностью излучения, диаграммами направленности, схожими с эквивалентной дипольной антенной, и значительно меньшими значениями эффективной площади рассеяния (ЭПР) в выключенном режиме The article discusses a plasma dipole antenna, which is designed to operate in the VHF band at a frequency of 140 MHz. Plasma dipole antennas differ from conventional dipole antennas in that the metal conductor is replaced by plasma in the discharge tube. The plasma dipole created by the discharge in the tube is capable of turning on and off in times of the order of microseconds. The use of a plasma antenna makes it possible to provide two modes of operation: active, when the plasma induces a conductive surface, and hidden, when the antenna becomes practically invisible to electromagnetic waves, and the plasma cloud is absent. We used electrodynamic modeling to determine the characteristics of the antenna. The results show that the characteristics of the plasma dipole antenna are close to those of the equivalent metal dipole, while the length of the plasma antenna is shorter. To determine the efficiency of the hidden mode of the antenna, we compared the characteristics of radar cross-section of the plasma antenna with the plasma cloud turned off and the equivalent metal dipole. The results obtained show that the plasma antenna has a high radiation efficiency, directional patterns similar to an equivalent dipole antenna, and significantly lower RCS values in the off mode

Deducing of Optical and Electronic Domains Based Distortions in Radio over Fiber Network

Managing the users multimedia and long-range based demands, the radio over fiber (RoF) mechanism has been introduced recently. RoF mingles the optical and radio communication frameworks to increase mobility and offer high capacity communication networks (CNs). In this paper, a full-duplex RoF-based CN is investigated for the next-generation passive optical network (PON), utilizing wavelength division multiplexing (WDM) technology. The desolations on account of optical and electronic domains (OEDs) are addressed, using dispersion compensation fiber (DCF) and optical and electrical filters, including modulation scheme. The analytical and simulation models are analyzed in terms of phase error (PE), radio frequency (RF), fiber length and input and received powers. The performance of the proposed model is successfully evaluated for 50 km range, −40 to −18 dBm received power, −20 to 0 dBm input power, where below 10−6 bit error rate (BER) is recorded. Thus, this signifies that the presented model exhibits smooth execution against OEDs impairments.

Issues with Modeling a Tunnel Communication Channel through a Plasma Sheath

We consider two of the most relevant problems that arise when modeling the properties of a tunnel radio communication channel through a plasma layer. First, we studied the case of the oblique incidence of electromagnetic waves on a layer of ionized gas for two wave polarizations. The resonator parameters that provide signal reception at a wide solid angle were found. We also took into account the unavoidable presence of a protective layer between the plasma and the resonator, as well as the conducting elements of the antenna system in the dielectric itself. This provides the first complete simulation for a tunnel communication channel. Noise immunity and communication range studies were conducted for a prospective spacecraft radio line.

ПЕТИНА ВИЧЕВА. ПРОБЛЕМИ НА ВЕРБАЛНАТА КОМУНИКАЦИЯ В ТЪРГОВСКОТО КОРАБОПЛАВАНЕ / PETINA VICHEVA. PROBLEMS OF VERBAL COMMUNICATION IN MERCHANT SHIPPING.

This book review presents Petina Vicheva’s monograph titled Problems of Verbal Communication in Merchant Shipping. The subject of the study is Maritime English and Standard Marine Communication Phrases (SMCP) in particular. The emphasis is on the use of SMCP in maritime radio communication. The objective of the monograph is to describe and analyse problematic situations that arise in verbal communication carried out over the radio at sea. The main conclusions are drawn at the end of the study. As SMCP is even more actively used by multinational crews, the monograph aims at providing linguistic strategies for effective maritime com-munication, thus contributing significantly to the safety of shipping.

DETERMINATION OF THE NORMS OF FREQUENCY-TERRITORIAL DIVERSION DURING THE DEVELOPMENT OF 5G TECHNOLOGY IN 3,4–4,2, 4,4–5, 14,5–15,35 GHZ FREQUENCY RANGES

The article presents scientific and technical proposals on the possibility of joint use of radio frequency spectrum of the fifth-generation mobile radio communication means and existing departmental radio-electronic facilities. On the basis of the load analysis, using the method of theoretical assessment of electromagnetic compatibility, the norms of territorial diversion between radio means are obtained. On the basis of the results of the calculations, it is possible to determine the subbands in which the joint use of radio means is possible, subject to optimization of the frequency-territorial plan and implementation of technical and organizational measures to ensure electromagnetic compatibility.

IoT-Based Tracking System of Transceiver Location

Object mapping based on location tracking methods has been widely used in various types of applications. Most tracking systems recently use existing technology and infrastructure such as satellite, cellular and wireless (RF) technology. These existing technologies are high-cost technology that needs authorized permission to be integrated to the novel technology. This research proposed a cheap point to point device technology to track a location of a transceiver using GPS in a portable infrastructure using Line of sight radio communication. The tracking system design is connected to the IoT system in order to be more accessible. The proposed system using GPS as an identifier of the transceiver coordinate location and 433MHz radio module as media communication between transmitter and receiver. The use of a 433MHz radio frequency module which is free-license adds value to the system so that it will be easily accessed. The design of portable and internet-based devices also gives a positive value in which the system does not have to depend on existing infrastructure and the system can also be reached even if it is placed in remote areas. The system test results show that the system can be well accessed up to a distance of 6.8 km.

DEPLOYMENT OF PROFESSIONAL VHF COMMUNICATION SYSTEMS IN THE ARCTIC REGION

The importance of the Northern Sea Route as a global transport corridor, used for transportation of national and international cargo, will only increase because of the currently observed climatic changes. Currently, the only stable communication system there is satellite. The paper presents the results of software modeling of a technological radio communication line based on the VHF trunking network for sea vessels following a group along the Northern Sea Route.

An Agile AI and IoT-Augmented Smart Farming: A Cost-Effective Cognitive Weather Station

Internet of Things (IoT) can be seen as the electricity of 21st century. It has been reshaping human life daily during the last decade, with various applications in several critical domains such as agriculture. Smart farming is a real-world application in which Internet of Things (IoT) technologies like agro-weather stations can have a direct impact on humans by enhancing crop quality, supporting sustainable agriculture, and eventually generating steady growth. Meanwhile, most agro-weather solutions are neither customized nor affordable for small farmers within developing countries. Furthermore, due to the outdoor challenges, it is often a challenge to develop and deploy low-cost yet robust systems. Robustness, which is determined by several factors, including energy consumption, portability, interoperability, and system’s ease of use. In this paper, we present an agile AI-Powered IoT-based low-cost platform for cognitive monitoring for smart farming. The hybrid Multi-Agent and the fully containerized system continuously surveys multiple agriculture parameters such as temperature, humidity, and pressure to provide end-users with real-time environmental data and AI-based forecasts. The surveyed data is ensured through several heterogeneous nodes deployed within the base station and in the open sensing area. The collected data is transmitted to the local server for pre-processing and the cloud server for backup. The system backbone communication is based on heterogeneous protocols such as MQTT, NRF24L01, and WiFi for radio communication. We also set up a user-friendly web-based graphical user interface (GUI) to support different user profiles. The overall platform design follows an agile approach to be easy to deploy, accessible to maintain, and continuously modernized.

Two-Time Procedure for Calculation of Carrier Frequency of Phasomodulated in Communication Systems

The use in radio communication systems of phase modulation of a signal intended for the transmission of useful information in a continuous mode creates the problem of frequency uncertainty of the received signal by frequency.In practice, it is not possible to implement frequency estimation in the conditions of chat uncertainty of the signal in the channel with low energy of the signal received in the continuous mode. Therefore, the estimation of the carrier frequency offset of the signal received relative to the nominal value is carried out before other synchronization procedures are included, namely: phase synchronization and clock synchronization. The paper generalizes the procedure and forms a two-step procedure for calculating the carrier frequency of the phase-modulated signal of a radio communication system for data transmission in a continuous mode, taking into account the condition of uncertainty of all signal parameters. Achieving the minimum observation interval in the given order of calculation of the carrier frequency is ensured by the use of the fast Fourier transform function. In order to analyze the effectiveness of this procedure, the process of estimating the carrier frequency of the phase-modulated signal of the radio communication system during data transmission in continuous mode and functional dependences of the maximum frequency in the signal spectrum and the minimum variance of carrier frequency estimation. This procedure allows a two-stage assessment of the carrier frequency according to the rule of maximum likelihood, taking into account the condition of uncertainty of all parameters of the signal received by the satellite communication system in a continuous mode with a minimum observation interval. Achieving the minimum observation interval in the given order of carrier frequency estimation is ensured by using the fast Fourier transform function and two estimation steps. The analysis of the efficiency of the estimation of the specified order was carried out on the basis of comparison of a ratio of the received minimum variance of an estimation of a carrier frequency and theoretically possible border of the minimum variance.

Electromagnetic Spectrum of the Corona Discharge and Their Fundamental Frequency

Historically, the Electromagnetic Compatibility (EMC) began with the disturbances at the radio navigation systems generated by the electrical power distribution lines; hence it was referred to as Radio Interference (RI). This disturbance is an Electromagnetic Interference (EMI). Although this type of EMI has been studied since the first decades of the past century, it still maintains a continued interest of the researchers, especially with the Corona Discharge (CD), generated by High Voltage Direct Current (HVDC) systems. Because of its design criterion and the concern that this phenomenon may affect the new radio communication systems in the very high frequency (VHF), ultra high frequency (UHF), and microwave bands, interest in their studies continues. In this chapter, an analysis of the electromagnetic spectrum of the CD is presented. The CD is generated at a short transmission line located within a semi-anechoic chamber. To be sure of the phenomenon, the CD is identified by its current pulse, which is well studied. The instruments used are an oscilloscope of 2 GHz and 2 GS/s, a spectrum analyzer, and an EMI test receiver. The results show that the CD concentrates its energy at frequencies below 70 MHz. In the UHF band, only narrowband signals very separated were found, with levels that cannot affect radio communication systems.