Radio Wave Propagation Conditions Research Articles

PROPOSALS TO IMPROVE THE INFORMATION CAPABILITIES OF COASTAL-BASED RADAR STATIONS FOR SURVEILLANCE OF SURFACE AND AIR OBJECTS

Sea-based radar stations (RS) are widely used for solving the tasks of radar surveillance of surface objects (SO) and air objects (AO). The subject of the article is the mechanisms of radio wave propagation in the boundary layer of the atmosphere. The aim is to investigate the possibilities of improving the accuracy of measuring the range and radial velocity of SO and AO observed beyond the line-of-sight of coastal-based RS. Objective: to analyse the spatial and temporal parameters and properties of waveguide layers above the water surface. Methods used: maximum likelihood and frequency. The following results were obtained. The results of experimental studies of seasonal and daily changes in the parameters of the lower troposphere layer in the Black Sea coastal zone and the parameters of tropospheric radio waveguides are presented. The procedure for calculating the energy transmission losses during radio wave propagation in the boundary layer of the atmosphere is presented, and the conditions for detecting SO and AO beyond the radar line-of-sight are determined. Recommendations for increasing the range of detection of SO and AO are given, which are associated with the possibility of predicting the existence of tropospheric radio waveguides by using data on the current conditions of radio wave propagation over the sea based on the signals of the automatic ship identification system AIS. Conclusions. Proposals have been developed to improve the accuracy of measuring the range and radial velocity of SO and AO at waveguide propagation of radio waves over the sea surface. A promising area for further research may be to identify ways to optimise the measurement of angular coordinates in modern RS during waveguide propagation of radio waves over the sea surface.

Automatic Placement Algorithm of Base Stations Trunking Communication Systems

to increase the efficiency of the trunking communication systems design process, an original algorithm for the automatic placement of base stations is proposed, taking into account the real conditions of radio wave propagation. The analysis showed that the existing methods allow you to place base stations manually, with a given step or automatically, but without taking into account the propagation of radio waves, which leads to poor-quality coverage of the required area with communication. The aim of the work is to reduce the complexity of designing a trunking communication system that is guaranteed to cover a given service area. It is proposed to calculate the service areas of base stations using a statistical model, as well as taking into account additional diffraction losses on the radio signal propagation path. The solution to the problem of automatic placement of base stations is based on the use of the proposed modified Hut model, which takes into account the terrain at the locations of the base and portable stations, as well as on the international recommendation for predicting signal propagation on a specific route for ground services. With automatic placement, the optimality criterion is fulfilled, which consists in placing the minimum number of base stations necessary to cover the required territory. An element of the novelty of the presented solution is that at the first stage of the calculation, the service area of the base station is determined by the statistical method, at the second stage, an updated calculation of the service area takes place taking into account the actual conditions of radio wave propagation at the binding site, and at the third stage, the zone of guaranteed customer service is determined. The use of the proposed algorithm makes it possible to reduce the complexity of the system design process and determine the sufficient number of base stations needed to cover a given area with communication. Appropriate software has been developed to apply the algorithm in real practice. To confirm the effectiveness of the algorithm, the paper presents comparative calculations of the time spent on designing a trunking communication system using the developed software and using the widely used RadioMobile program.

Modeling of the Propagation of LF–MF–SF Bands Electromagnetic Waves on Arctic Paths

The article demonstrates that the conditions of LF–MF–SF bands electromagnetic wave propagation over the “ice-sea” structure with highly inductive impedance are more favorable than over the sea without ice because of the appearance of surface electromagnetic waves (SEW). It was determined that the conditions of radio wave propagation over ice paths depend on a frequency, ice thickness and distance from the transmitter within the 100 kHz – 5 MHz range on the paths with ice thickness from 0.6 to 2.7 meters.

Determination of radio wave propagation conditions in the atmosphere of Hanoi using the radiosonde data of balloons

This article uses radiosonde data of balloons in Hanoi to determine the radio refractive index and the conditions of radio wave propagation in the atmosphere. The research results in the three years 2016–2018 show the highest average radio refractivity, the maximum radio refractivity difference between the years. Secondly, radiosonde data are used to estimate the accuracy of global ITU models, and showed that the radio refractivity’s difference between the ITU-R model and the observed value by radiosonde method is up to 60 N-units at a lower altitude of atmosphere. In conclusion, it is recommended to use radiosonde data instead of the ITU model (where available) to obtain refractive index when studying wave propagation conditions in the atmosphere.

Auroral Ionosphere Model with PC Index as an Input

Auroral Ionosphere Model (AIM-E) is designed to calculate chemical content in the high-latitude E region ionosphere and takes into account both the solar EUV radiation and the electron precipitation of magnetospheric origin. The latter is extremely important for auroral ionosphere chemistry especially in disturbed conditions. In order to maximize the AIM-E timing accuracy when simulating highly variable periods in the course of geomagnetic storms and substorms, we suggest to parameterize the OVATION-Prime empirical precipitation model with the ground-based Polar Cap (PC) index. This gives an advantage to: (1) perform ionospheric simulation with actual input, since PC index reflects the geoeffective solar wind conditions; (2) promptly assess the current geomagnetic situation, since PC index is available in real-time with 1 min resolution. The simulation results of AIM-E with OVATION-Prime (PC) demonstrate a good agreement with the ground-based incoherent scatter radar data (EISCAT UHF, Tromso) and with the vertical sounding data in the Arctic zone during events of intense particle precipitation. The model reproduces well the electron content calculated in vertical column (90–140 km) and critical frequency of sporadic E layer (fOEs) formed by precipitating electrons. The AIM-E (PC) model can be applied to monitor the sporadic E layer in real-time and in the entire high-latitude ionosphere, including the auroral and subauroral zones, which is important for predicting the conditions of radio wave propagation.

Determination of radio wave propagation conditions in the atmosphere of Hanoi using the meteorological data

This article uses the data of radio occultation and the radiosonde data to determine radio refractive index and wave propagation conditions in the atmosphere of the Hanoi area. The content of this article uses the data of radio occultation in 2014-2016 and the radiosonde data in 2016-2018, showing that the radio refractive index tends to decrease with altitude, the maximum average value of radio refractivity is 370 N-units, the largest radio refractivity difference between years is not more than 11 N-units, at high altitudes the radio refractivity value is close to the value at standard model of the ITU-R while at a small altitude the difference between the model value and the observed value is up to 60 N-units, the vertical gradient of refractivity and the effective earth radius coefficient is independent with altitude. Based on radio refractivity, it is possible to determine tropospheric delay, which is input data for problems such as satellite positioning, altimetry satellite and under-the-horizon radar.

Characteristics of the electromagnetic environment created by radiations of user equipment of ...4G/5G/6G cellular (mobile) communications in buildings

The goal of the work is to substantiate the technique for assessing the intensity of electromagnetic background generated by the set of radiating user devices of mobile communications in multi-storey buildings. For known empirical models of radio wave propagation in buildings, expressions are obtained for the probability distribution density and expectation of the power flux density of electromagnetic fields generated inside building by these sources from various parts of the building's interior space: from the near zone with radio wave propagation conditions similar to free space; and from the far zone, for which, along with intense attenuation of radio waves due to internal obstacles, a «quasi-waveguide» propagation of radio waves along corridors and industrial premises is also possible in certain directions. Relationships are obtained for the average levels of individual components of the electromagnetic background, determined as scalar sums of power flux density values of the fields generated by the sets of radiating devices of both the near zone and the far zone as a whole or its individual parts, characterized by different conditions of radio wave propagation. A method is proposed for assessing the electromagnetic background inside buildings based on approximation of sections of the inner surface of the premises in which the observation point is located, and the outer surface of the building, in the inner space of which radiation sources are randomly distributed, by the corresponding sections of the inner and outer spherical surfaces that are the subtend areas of the corresponding solid angles, in space elements of which a different spatial densities and radiation powers of sources and different conditions of radio wave propagation are possible. The results can be used to analyze the electromagnetic ecology of habitat and the electromagnetic safety of population at the full-scale implementation of 4G/5G/6G mobile communications, as well as to analyze the electromagnetic compatibility of systems using frequency bands for mobile communications on a primary and secondary basis.

Comparative Analysis of the Propagation Conditions of Millimeter Radio Waves at Radio Astronomy Polygons in Russia and Uzbekistan

Comparative Analysis of the Propagation Conditions of Millimeter Radio Waves at Radio Astronomy Polygons in Russia and Uzbekistan

Characterization of high latitude radio wave propagation over Canada

High frequency (HF) radio wave propagation is sensitive to ionospheric disturbances caused by space weather. Changes in propagation conditions can be directly measured with an HF transmitter/receiver link. This paper presents data from one such link, consisting of a transmitter located in Ottawa, ON, Canada, and a directional receiver located in Alert, NU, Canada. The transmitter emits signals at 6 distinct frequencies between 5.4 and 14.4 MHz on a set schedule that are detected and processed by the receiver. Based on 644 days of archived data, a statistical analysis characterizing HF radio wave propagation conditions over the course of the day and over the year are presented. HF propagation is found to follow the regular diurnal variation in ionospheric density, modulated by seasonal trends. A new method for distinguishing space weather effects from diurnal changes to HF propagation is presented, which utilizes quiet day baselines, similar to riometer quiet day curves. This method allows for easy analysis of the impacts of space weather on HF radio propagation between two points. This method is applied to an auroral absorption event that occurred on 06 June 2016, and is used to successfully distinguish auroral absorption related dropouts from dropouts related to daily ionospheric variation.

Моделювання робочої зони локальної RTLS-системи району надзвичайної ситуації

A mathematical model of a differential-rangefinder local positioning system has been developed, which in real time makes it possible to predict the working area of the system, taking into account the construction barriers of the emergency zone. The conditions of propagation of high-frequency signals, which determine the quality of positioning and the accuracy characteristics of the system, are taken into account. To simplify the simulation, a number of assumptions were made regarding the parameters of the obstacles and the conditions of radio wave propagation, which make it possible to simplify the prediction process. On the basis of the geometric criterion and the criterion of maximum removal, a modified geometry coefficient (zone coefficient) was obtained, which is proposed to be used as the basis for a mathematical forecasting model. Using this criterion, a computational algorithm and a program for operational forecasting of the working area of local positioning have been developed, which make it possible to take into account the influence of the number of beacons, the geometry of the system and the location of building barriers to the propagation of radio signals on the shape of the working area. In the process of modeling, both geometric and general physical laws of the formation of the field of radio navigation support were taken into account. A study of the operation of the modeling system was carried out in the presence of several radio beacons, in the absence and in the presence of several construction barriers within the emergency zone. The developed mathematical model makes it possible to calculate the size of the positioning zones with the determination of the boundary conditions for the reliability and accuracy of the navigation support of rescuers. Taking into account the process of predicting the impact of obstacles in the emergency zone on the type and size of the working area of the positioning system allows the head of emergency response to make the right management decision, ensure safe working conditions for rescuers and optimize emergency response.

A Review on the Effects of Radio Refractivity and Atmospheric Parameters on Signal Quality at Ultra High Frequency (UHF)

Refractivity is an important factor in predicting the performance of radio link. The structures of the refractive index of the troposphere are responsible for many complicated mechanisms such as, multipath effects, absorption, scattering of radio signals, etc. and these mechanisms can cause a lot of propagation impairment such as, loss of signal for mobile communication, the accuracy of tracking radio source (such as stars) with radio telescopes, radar system etc. Understanding the effects of the weather on radio wave propagation will help to improve the quality of radio signals, as the Weather variables are useful ingredients in the predictions of refractivity distributions and the anomalous radio wave propagation conditions of the atmosphere. This study contends that refractivity variations significantly affects received signal strength at Ultra High Frequency (UHF) and gave a brief theoretical background on Electromagnetic wave, Atmospheric effects on radio propagation anomalous propagation condition and the mathematical expression for refractive index and refractivity of the troposphere. Also, the paper review related articles in the following area; refractive index and refractivity of the troposphere, effects of weather variables and refractivity of troposphere. The analysis of the review articles summits that, refractivity reveals seasonal variations with high value in rainy season and low values in dry season. Also observed from the review articles, is that the diurnal variations are influenced by three atmospheric parameters; water vapour has the greatest effect on refractivity variations followed by temperature and pressure. Furthermore, the Refractivity is function of local meteorological parameters. Eventually, the study suggests that, the effect of Atmospheric parameters and consequently the Radio Refractivity should be compensated for when designing wireless communication links in an environment.

МАТЕМАТИЧНА МОДЕЛЬ ФОРМУВАННЯ СИГНАЛІВ З АДАПТАЦІЄЮ ПО ШВИДКОСТІ ПЕРЕДАВАННЯ ІНФОРМАЦІЇ НА ОСНОВІ ДОСКОНАЛИХ ДВІЙКОВИХ МАТРИЦЬ

Предметом дослідження є методи та моделі формування сигналів адаптивних видів модуляції. Мета: забезпечення високої пропускної здатності та спектральної ефективності, для даних умов розповсюдження радіохвиль, шляхом використання запропонованої моделі формування сигналів з адаптацією по швидкості передавання інформації на основі досконалих двійкових матриць. Результати досліджень. В роботі представлено результати аналізу напрямів розвитку та основних властивостей безпроводових мереж передачі даних. Встановлено, що лише у разі забезпечення комплексу розглянутих властивостей, безпроводова мережа може виконувати своє функціональне призначення – забезпечувати доставляння повідомлень у необхідному обсязі й із заданою якістю. Розглянуто принципи реалізації методів адаптивної модуляції в перспективних засобах бездротового зв’язку. Використання адаптивної модуляції дозволяє забезпечити найкращу пропускну здатність для даних умов розповсюдження радіохвиль, розглянута в роботі схема адаптивної модуляції дозволить звести ймовірність виникнення помилки в передачі до мінімуму. Запропоновано математичну модель формування сигналів з адаптацією по швидкості передавання інформації на основі досконалих двійкових матриць. Розглянуто основні принципи функціонування пристрою управління моделі формування сигналів з адаптацією по швидкості передавання інформації на основі досконалих двійкових матриць. Висновки та область застосування результатів досліджень. Запропонована математична модель формування сигналів з адаптацією по швидкості передавання інформації на основі досконалих двійкових матриць. Використання запропонованих сигналів з адаптацією по швидкості передавання інформації на основі досконалих двійкових матриць дозволить забезпечити високу пропускну здатність та спектральну ефективність, для даних умов розповсюдження радіохвиль, перспективних радіоінтерфейсів

Analysis of properties of integral equations of the field in the aperture of an open coaxial probe

Acoustic sounding systems are an effective means of monitoring the lower troposphere. They find application in various fields of science and technology. The problem of developing acoustic methods and means for remote sensing of the lower atmosphere remains relevant given the importance of information on the state of the atmospheric boundary layer for the functioning of areas such as meteorology, ecology, transport, especially aviation, agriculture and others. This problem has both theoretical and technical aspects. These, for example, include solving inverse problems of sound propagation in a turbulent atmosphere, compensation for wind shear, and others. A number of companies and universities create acoustic locators – sodars and radio-acoustic sounding systems. The paper discusses their application for assessing the propagation conditions of radio waves on surface paths near the land-sea boundary. Despite the development of satellite systems for transmitting information and positioning, traditional means of communication and navigation are still in demand. They occupy their niche in the general nomenclature of radio equipment, while remaining indispensable in emergency warning systems, navigation in limited areas, in emergency situations. The effectiveness of these tools largely depends on operational information on the state of the propagation paths of radio waves. One of the most complex objects for assessing the propagation conditions of radio waves is the atmospheric boundary layer. Its condition is largely determined by the state of the underlying surface, which in turn depends on the time of day, season, rainfall and other factors. To date, only very limited theoretical models of dynamics have been created for some states of the atmospheric boundary layer despite the considerable efforts of meteorological specialists. Therefore, information is required on the spatial distribution of meteorological parameters. The most promising solution to this problem is the use of remote non-contact sensing methods based on one or another form of wave processes. Acoustic waves are significantly more sensitive to changes in air parameters than other types of radiation. The objectives of this work are to present a comprehensive methodology for using remote, non-contact sensing methods, theoretical representations of the dynamics of APS and modern software for solving problems of promptly determining the conditions of RRS on surface paths and assessing the most promising ways of developing methods and means for obtaining this information.An example of the experimental results of radio-acoustic sounding and sodar monitoring of the atmospheric boundary layer near the land-sea boundary is given. Based on these results, the spatial-temporal distribution of the index of refractive index is estimated. An analysis of the results is given. The choice of ways to develop means of acoustic sensing and processing the information received is substantiated, taking into account the progress of electronic devices and systems.

Методика застосування сигналів удосконаленої модуляції циклічним зсувом коду з адаптацією по швидкості передавання інформації в перспективних радіоінтерфейсах

This paper presents the results of the analysis of the directions of development of special purpose radio communication systems. The method of application of signals of advanced modulation by cyclic shift of the code with adaptation on speed of information transmission in perspective radio interfaces is offered. The procedure of estimation of radio wave propagation medium and transmission and reception of control signals is considered; models of formation and correlation processing of signals of advanced modulation by cyclic shift of code with adaptation on the speed of information transmission. The technique of application of advanced modulation signals by cyclic code shift with adaptation on the speed of information transmission in perspective radio interfaces is offered. The use of the proposed method of application of signals of advanced modulation by cyclic shift of the code with adaptation on the speed of transmission of information in perspective radio interfaces will allow to provide high bandwidth and spectral efficiency, for these conditions of radio wave propagation.

Influence of synchronization errors оn the noise immunity of coherent reception of M-PSK signals

Signals with multiple phase-shift keying (M-PSK) have long been successfully used for highspeed information transfer in many applications – a number of adopted protocols of IEEE 802.11 wireless networks, digital satellite television DVB-S, DVB-S2/S2X systems, cellular networks CDMA and others. The most important characteristic of such systems is their noise immunity, which depends not only on the propagation conditions of radio waves in the communication channel, but also on the quality of operation of the component nodes of the information transmission systems themselves. The paper investigates the influence of the inaccuracy of estimating the frequency and phase of the carrier and the inaccuracy of the clock synchronization system on the noise immunity of coherent reception of M-PSK signals. Analytical expressions were obtained by statistical radio engineering methods. The expressions allow calculating the dependence of the probability of a bit error on the signal-to-noise ratio for various errors of the receiver auxiliary systems. In this case, the magnitudes of the errors were assumed to be either constant (static error) or dynamically changing (dynamic error). The dynamic errors were modeled using the Monte Carlo method, and the dynamic errors themselves were assumed to be Gaussian random variables. It is shown that the inaccuracy of estimating these parameters strongly influences the noise immunity of the coherent reception of the M-PSK signal, and this effect increases with increasing signal positionality. Estimates of the maximum permissible errors of the analyzed systems are given. When M-PSK signals are received, a tolerable value of the frequency of the reference oscillations can be considered as a ∆ωTs value of about 0.05. The allowable inaccuracy of the carrier phase estimation depends on the positioning of the signal and varies from π/36–π/72 for 2PSK to π/180 for 32PSK. The allowable time offset of the clock moments can be considered the value of 3–5% of the clock interval duration.

Forecasting High-Frequency Radio Communications Based on GLONASS/GPS Navigation System Data

The paper considers the possibility of forecasting high-frequency (HF) radio communications based on GLONASS/GPS navigation satellite system data. The authors comparatively analyze the the calculation data for the maximum usable frequencies for short- (100 km) and medium-range (800 km) HF radio communications. Good agreement of the calculated data has been obtained using the results of probe measurements and the hardware–software complex (HSC) for monitoring the ionosphere. It is shown that real-time HSC monitoring of the ionosphere parameters allows successful assessment of the current propagation conditions of HF radio waves.

Analysis of Propagation of Electromagnetic Waves in Difficult Conditions by the Parabolic Equation Method

Studies devoted to the application of numerical solutions of the parabolic equation to the prediction of propagation conditions of radio waves traveling above the ground surface are briefly reviewed. Emphasis is placed on the analysis of the physical irregularities of propagation of radio waves in difficult conditions (above the sea surface, including formation of evaporation ducts and in forests, including the influence of forest and terrain profiles on the radiation field of phased array antennas).

REGISTRATION OF MOTION PARAMETERS OF AIRCRAFT MEASURING POINT AT PARALLEL PLACEMENT OF MOBILE RADAR STATIONS FOR COMPLEX OF EXTERNAL MEASUREMENTS

The paper presents a practically implemented version of the placement of posts for the complex of external measurements on the basis of mobile radar centimeter range stations, built on the technology of cascaded active phased waveguide‑slot antenna arrays for recording the parameters of the aircraft measuring point as a typical air moving object. The main technical characteristics of the posts for the complex of external measurements and registration of the parameters of motion parameters of air objects are proposed, the restrictions on the range of measurement and review sectors are determined. The influence of environment on the propagation conditions of radio waves, limiting the choice of the frequency range of radar stations, the results of the calculation of linear attenuation in oxygen, water vapor and the total attenuation for the wave range from 10 to 100 GHz are presented. The theoretical issues of designing radar stations sector review with the use of electronic scanning and rangefinder‑goniometer method of measurement are raised.

The analytical look of the current technologies of the tropospheric and radio-relay

The relevance of the task of creating a mobile combined station of digital tropospheric and satellite communications of the microwave range, which simultane­ ously operates in 2 modes: horizontal communication and direct visibility, substantiates an analytical review of the current state of tropospheric communication in the world. The technical characteristics of the advanced developments of digital troposphere stations and control systems of foreign companies Comtech Systems, Raytheon Corporation, General Dynamics, Advantech Wireless are presented. It is shown that the RTM-100 tropospheric modem, with a bandwidth of 50 Mbit/s and more, which provides stable communications under multipath conditions when using direct error correction turbocompression (FEC) and supports work with Gigabit Ethernet (GbE) data ports and SNMP protocol is the key Elements for creating a new mobile combined digital troposphere and satellite communications station. The analysis of the current state and development trends of radio-relay communication, as well as the spectrum of widespread use of modern digital radio-relay communication. The OptiX RTN 900, a new generation of IP-based digital radio relay system with a split structure, is one of the first systems to support TDM, packet and hybrid transmission platforms. The system supports communication in 2G networks, voice and data services in 3G networks, broadband data services in LTE networks. Radio relay systems of NEC, NERA, Huawei Technologies, ZTE, Nokia Siemens Networks (former Alcatel-Lucent) companies implement adaptive modulation and coding (Adaptive Coding & Modulation — ACM), which allows you to change the parameters of the radio channel when changing the propagation conditions of radio waves and thereby technology AFM allows the operator to reduce their capital costs during the construction of RRL by installing antennas of smaller diameters or by building longer communication intervals. The bandwidth of digital radio relay stations has grown to 5.5 Gb / s (Ericsson) and for this new sections of the millimeter wave range have been mastered: 71…76 GHz, 81...86 GHz. The development of the terahertz frequency range opens up great op­ por­ tunities for a significant increase in throughput and security and secrecy. An analytical analysis showed the promise of creating a mobile combined station of the digital tropospheric and satellite microwave range, corresponding to the development trends of tropospheric and microwave radio communications, is an urgent task for Ukraine.

Ionospheric Weather During Five Extreme Geomagnetic Superstorms Since IGY Deduced With the Instantaneous Global Maps GIM‐foF2

AbstractAn assessment of the ionosphere perturbations can be made through the construction of the global instantaneous maps of the foF2 critical frequency (GIM‐foF2) and the ionospheric weather index maps GIM‐Wf. These maps can offer a potentially useful tool to provide users with a proper selection of the best radio wave propagation conditions over a certain area and also be used to help mitigate the effects of the disturbances on HF (High Frequency) communication and Global Navigation Satellite System positioning. This paper presents results of reconstruction of the ionospheric weather during five of the most intense superstorms observed since International Geophysical Year, IGY (1957, 1958, 1959, 1989, and 2003) with the instantaneous global maps of the F2 layer critical frequency, GIM‐foF2, and the ionospheric weather index maps, GIM‐Wf. The intensity of the ionospheric superstorm is characterized by the planetary Wfp index derived from GIM‐Wf maps. Superposed epoch analysis of the extreme superstorms is made during 24 hr before the Wfp peak (time zero t0 = 0 hr) and 48 hr afterwards. Model relationship is established between mean Wfp profile and geomagnetic superstorm profiles demonstrating saturation of the ionospheric storm activity toward the peak of geomagnetic storm. Time lag of Wfpmax is found equal to 9 hr after AEmax, 6 hr after apmax and aamax, and 2 hr after Dstmin, which allows model forecast of ionospheric superstorm when geomagnetic superstorm is captured with one or more of geomagnetic indices.