Attenuation Of Electromagnetic Signal Research Articles

Influence of strong solar proton events on propagation of radio signals in the VLF range in a high-latitude region

In this paper, we examine the features of RSDN-20 signal propagation in a high-latitude Earth–ionosphere waveguide during solar proton events, using computational experiment methods. We have analyzed two proton ground-level enhancement (GLE) events of December 13, 2006 (GLE70) and September 10, 2017 (GLE72). Electron density profiles were constructed using the Global Dynamic Model of Ionosphere (GDMI) and the RUSCOSMICS model, developed at PGI. We present estimated phase and amplitude changes in RSDN-20 signals during precipitation of high-energy protons in the high-latitude region of the Earth–ionosphere waveguide. From the results of computational experiments and the analysis of the electromagnetic signal attenuation based on analytical Maxwell’s equation system solution in magnetized ionospheric plasma, we have found a pattern in the signal attenuation frequency dependence associated simultaneously with the signal reflection height, electron density profiles, and the collision frequency of electrons with neutral particles and ions. We discuss limitations of the computational experiment method and compare simulation results with data from Lovozero and Tuloma observatories.

Влияние сильных солнечных протонных событий на распространение радиосигналов в диапазоне ОНЧ в области высоких широт

In this paper, we examine the features of RSDN-20 signal propagation in a high-latitude Earth–ionosphere waveguide during solar proton events, using computational experiment methods. We have analyzed two proton ground-level enhancement (GLE) events of December 13, 2006 (GLE70) and September 10, 2017 (GLE72). Electron density profiles were constructed using the Global Dynamic Model of Ionosphere (GDMI) and the RUSCOSMICS model, developed at PGI. We present estimated phase and amplitude changes in RSDN-20 signals during precipitation of high-energy protons in the high-latitude region of the Earth–ionosphere waveguide. From the results of computational experiments and the analysis of the electromagnetic signal attenuation based on analytical Maxwell’s equation system solution in magnetized ionospheric plasma, we have found a pattern in the signal attenuation frequency dependence associated simultaneously with the signal reflection height, electron density profiles, and the collision frequency of electrons with neutral particles and ions. We discuss limitations of the computational experiment method and compare simulation results with data from Lovozero and Tuloma observatories.

Mapping the integrity of rock mass with GPR: case study in decommissioning mining

Slopes are built for the purpose of extracting ore, in the case of mining, or access roads in civil works. The excavation of slopes in tropical countries is facilitated by the thick layer of soil formed from the more intense weathering when compared to other countries. However, the residence time of water in the soil is relatively longer and consequently allows the accumulation and percolation of water through rock fractures even in the dry period. These factors induce a greater probability of occurrence of ruptures. Mines in the decommissioning phase must guarantee slope stability conditions even after closure in order to comply with legislation and environmental safety. In this work, the slopes of a decommissioning mine were investigated using geophysical methods (GPR) and structural analysis of the rock mass. The results were presented in the form of radargrams that correlate distance and depth of investigation. Structural data served as the basis for the execution of kinematic analyzes for planar and wedge ruptures. The analysis of the results allowed the correlation between electromagnetic signal attenuation zones, with the presence of water and the occurrence of ruptures. Thus, the GPR results allowed the recognition of structural discontinuities, accumulation zones and water flow.

Study on The Scattering Characteristics of Electromagnetic Wave with Dielectric Band

When electromagnetic signal penetrates medium, its signal intensity will decrease and even change the polarity of electromagnetic wave due to the scattering of electromagnetic wave. Electromagnetic wave signal propagation in rainy days, fog days, dust and another medium electromagnetic signal attenuation phenomenon. Since raindrops, haze particles, dust particles and other media have different degrees of electric quantity, in order to measure the effect of charge itself on electromagnetic wave attenuation, this paper involves the attenuation experiment of electromagnetic wave with dielectric plates. PP board, PVC board and PMMA board are selected to conduct experimental research on the influence of electromagnetic signal attenuation.

Electrical, Thermo-Electrical, and Electromagnetic Behaviour of Epoxy Composites Reinforced with Graphene Nanoplatelets with Different Average Surface Area.

The influence of the average surface area of different graphene nanoplatelets (GNP) on the thermo-electrical behaviour, associated with Joule heating, and the attenuation of electromagnetic signals of epoxy composites has been studied, analysing the effect of the morphology obtained as a function of the dispersion time by ultrasonication and the GNP content added. Gravity moulding was used as the first stage in the scaling-up, oriented to the industrial manufacture of multilayer coatings, observing a preferential self-orientation of nanoparticles and, in several conditions, a self-stratification too. The increase of sonication time during the GNP dispersion provides a decrease in the electrical conductivity, due to the GNP fragmentation. Instead, the thermal conductivity is enhanced due to the higher homogeneous distribution of GNPs into the epoxy matrix. Finally, the lower surface area of GNPs reduces the thermal and electrical conductivity due to a greater separation between nanosheets. Regarding the study of the attenuation of electromagnetic waves, it has been discovered that in the frequency range from 100 Hz to 20 MHz, this attenuation is independent of the direction of analysis, the type of graphene, the sonication time, and the state of dispersion of the nano-reinforcement in the matrix. Furthermore, it has also been observed that the conservation of the constant shielding values for the three types of GNPs are in a range of average frequencies between 0.3 and 3 MHz.

Electromagnetic Signal Attenuation Characteristics in the Lunar Regolith Observed by the Lunar Regolith Penetrating Radar (LRPR) Onboard the Chang’E-5 Lander

The Chinese Chang’E-5 probe landed in the Mons Rümker of Oceanus Procellarum on the near side of the Moon. The lunar regolith penetrating radar (LRPR) carried by the Chang’E-5 probe allows for the determination of in situ lunar regolith dielectric properties, which are probably related to the age and chemical composition of the regolith. In this paper, we analyze the Chang’E-5 LRPR data with the frequency shift method to estimate the loss tangent of the lunar regolith within a depth of ∼2.8 m. The loss tangent of the Chang’E-5 landing site is constrained to be 0.0148 ± 0.0016, which is substantially higher than that of the typical lunar regolith. The high loss tangent is found to be characteristic of the young basalt age (∼2.0 Ga) and high TiO2+FeO content (28.21 ± 1.57%) of the Chang’E-5 landing site. Integrated analysis of results from Chang’E-3, Chang’E-4, and Chang’E-5 show that the younger is the geologic age of the mare unit, the greater is the loss tangent of the lunar regolith, and the weaker is the radar electromagnetic signal penetrating ability.

ERT and GPR Prospecting Applied to Unsaturated and Subwater Analogue Archaeological Site in a Full Scale Laboratory

Geophysical techniques are widely applied in the archaeological field to highlight variations of the physical behaviour of the subsoil due to the presence of ancient and buried remains., Considerable efforts are required to understand the complexity of the relationship between archaeological features and their geophysical response where saturated conditions occur. In the case of lacustrine and wetland scenarios, geophysical contrasts or electromagnetic signal attenuation effects drastically reduce the capabilities of the geophysical methodologies for the detection of structures in such conditions. To identify the capability of the electrical and electromagnetic methods in different water-saturated scenarios, an experimental activity was performed at the Hydrogeosite CNR laboratory. The test allowed us to analyze the limits and potentialities of an innovative approach based on the combined use of the ground-penetrating radar and 2D and 3D electrical resistivity tomographies. Results showed the effectiveness of the ground-penetrating radar for detecting archaeological remains also in quasi-saturated and underwater scenarios despite the em signal attenuation phenomena; whilst the results obtained involving the resistivity tomographies offered a new perspective for the archaeological purposes due to the use of the loop–loop shaped array. Moreover, the radar signal attenuation, resolution and depth of investigation do not allow to fully characterize the archaeological site as in the case of the scenarios with a limited geophysical contrast (i.e., water-saturated and arid scenarios). The experimental tests show that these limits can be only partially mitigated through the integration of the geophysical methodologies and further efforts are necessary for improving the results obtainable with an integrated use of the adopted geophysical methodologies.

РЕЗОНАНСНІ ВЛАСТИВОСТІ СЕКЦІЇ ПРЯМОКУТНОГО ХВИЛЕВОДУ Х-ДІАПАЗОНУ З НЕОДНОРІДНИМ ДІЕЛЕКТРИКОМ ВСЕРЕДИНІ

Subject and Purpose. The subject of this research relates to quality parameters of substances with dielectric properties, while the main aim is development of a microwave-band remote sensing technique for measuring quality parameters of solids and loose materials. Methods and Methodology. The work is based on electromagnetic methods for determining substance quality by means of calculations and measurements of microwave signal attenuation in the substance of interest. The methods employed involve electrodynamic analysis of multilayered structures, the analytical method of moments, integral equations of diffraction theory, and objective function optimization. For a certain set of substances, preliminary calibrations and parameter storage are performed, intended for use in the determination of electromagnetic wave attenuation in the substance of interest. By comparing electromagnetic wave attenuation in the substance under testing with correspondent values shown by pre-calibrated samples, with their sets of parameters, it is possible to judge on the quality of the material under consideration. Results. By applying diffraction-theoretic methods of wave analysis in multilayered structures, the electromagnetic field attenuation in a substance (building bricks) has been calculated. The calculatеd results concerning electromagnetic signal attenuation in the test substance were compared with corresponding microwave measurements, thus permitting construction of the structural and mathematical model for the determination of the substance (building bricks) quality. The studies made it possible to evaluate the overall electrodynamic range of the measuring device, choosing the best options for the transmit and receive antenna sensors and the measuring equipment. The method of moments has been used to derive three-dimensional radiation patterns in the proximity of the device and the gain factor of the antenna sensors, wherefrom estimating the mutual electromagnetic effect that the sensors and the test substance may have on each other. Conclusion. Further development of the proposed method may imply refinement of the structural and mathematical models underlying estimation of quality parameters, determination of the overall dynamic range of the microwave-band measuring device, and provisions for automated real-time quality control and monitoring (for instance, on a conveyor), while maintaining conformance to applicable eco-standards concerning microwave intensity levels produced by the device.

Applicability of the ultra-high radio frequency band (UHF) for hydrometeor detection by phase difference method

Hydrometeors (rain, fog and ice crystals) affect the transmission of electromagnetic signals. Previous research showed that alterations in the signal (amplitude and phase) are affected by the composition of the atmosphere, e.g. the presence of hydrometeors. The majority of hydrometeorological detecting methods are based on the attenuation of electromagnetic signals as they penetrate the atmosphere. Novel methods based on monitoring of parameters of the signal appeared in recent time. This article presents the first results from our investigation of how hydrometeors affect the phase differences in signals transmitted by BTS stations. Cell phone operators transmit electromagnetic signals in the 1 GHz frequency band. This paper describes a novel concept of how phase differences between two signals arriving at two different antennas can be used to detect hydrometeors. Although the described concept is assumed to be independent from the signal strength, the analysed signal must be detectable. The primary advantage of the proposed passive method is that the signal is almost ubiquitous and does not require demodulation. In densely populated areas, the network of BTS stations reaches a spatial density of 1 station per 1 km2 which gives excellent opportunity to use the signal for detection purposes.

Multi-Dimensional Underwater Point Cloud Detection Based on Deep Learning.

Numerous sensors can obtain images or point cloud data on land, however, the rapid attenuation of electromagnetic signals and the lack of light in water have been observed to restrict sensing functions. This study expands the utilization of two- and three-dimensional detection technologies in underwater applications to detect abandoned tires. A three-dimensional acoustic sensor, the BV5000, is used in this study to collect underwater point cloud data. Some pre-processing steps are proposed to remove noise and the seabed from raw data. Point clouds are then processed to obtain two data types: a 2D image and a 3D point cloud. Deep learning methods with different dimensions are used to train the models. In the two-dimensional method, the point cloud is transferred into a bird’s eye view image. The Faster R-CNN and YOLOv3 network architectures are used to detect tires. Meanwhile, in the three-dimensional method, the point cloud associated with a tire is cut out from the raw data and is used as training data. The PointNet and PointConv network architectures are then used for tire classification. The results show that both approaches provide good accuracy.

Istraživanje klizišta metodama geoelektričnog skeniranja i georadara - neki primeri

Geotechnical investigations of landslides for future mitigation are a complex task. To obtain relevant information, various geophysical methods are used, with varying degrees of success. The geoelectrical scanning method, also known as Electrical Resistivity Tomography (ERT) has been successfully applied in several locations in Serbia in the las three decades. The geoelectrical scanning method was used during investigations of landslides: Umka, Lukovska banja, Tara, and Trandžament, while both geoelectrical scanning and Ground Penetrating Radar (GPR) were utilized at the Trandžament landslide. The achieved results from both methods are mutually correlated at the Trandžament landslide. Correlation of GPR data with geoelectrical scanning data was only possible since there were no nearsurface low resistivity zones in the Trandžament landslide body. Otherwise, electromagnetic signal attenuation would be high in the presence of near-surface low resistivity zones, and a quality signal would be impossible to detect at the receiving antenna.

Analysis of Groundwater Contamination Level in Residential Areas Around Cipayung Landfill Using Ground Penetrating Radar

Cipayung Landfill is the last disposal location of waste processing in Depok City, West Java. In a day, approximately 800 tons of garbage is dumped, which is then processed by being burned and left to decompose for inorganic and organic waste, respectively. However, poor waste management has resulted in an accumulation that continues to this day. This creates a variety of problems, especially leachate contamination that infiltrates to the groundwater, flows along and threaten the health of residents who live in the vicinity. This liquid contains toxins and hazardous materials. Therefore, it is essential for residents to know the level of contamination occurred and its dispersion, along with actions that must be taken to reduce the impact of pollution. In this study, we map the distribution of contaminated groundwater using the geophysical ground penetrating radar method, together with the chemical analysis of water samples. Ground penetrating radar has been useful to detect the change of permittivity and conductivity of layers below the surface. It is possible to mark off the contaminated groundwater to the fresh one indicated from an extensive amount of electromagnetic signal attenuation. This study suggests that there is contamination occurred in radius up to hundreds of meters from the landfill site. The result of this community-based research gives an advisable policy regarding waste management and groundwater usage in this area.

Rainfall estimation using a microwave link based on an improved rain-induced attenuation model

ABSTRACTTheoretical analyses show that both the rain-induced attenuation of electromagnetic signals and rainfall intensity are relative to the raindrop size distribution (DSD). In this paper, an improved rain-induced attenuation method is proposed to enhance the rainfall estimation accuracy through microwave links. The model is established through nonlinear fitting with the local DSD measured in Nanjing, China. The method for calculating the rain-induced attenuation of the microwave links is presented based on the calculation of the microwave path loss, air attenuation, and instrument attenuation. Data from an experiment with a 6.57-km microwave link of 15–20 GHz in Nanjing are used to test the improved model. The rainfall intensity estimation and rainfall depth determined by the proposed model is closer to the disdrometer measurement than is the estimation by the specific attenuation model of the International Telecommunication Union (ITU). Results from the experiment indicate that the proposed model has higher accuracy with respect to rainfall estimation and is feasible in practice. Therefore, it is essential to establish the local rain-induced attenuation model when estimating rainfall using microwave links.

Analysis of Vertical Profiles of Precipitable Liquid Water Content in a Tropical Climate Using Micro Rain Radar

In this paper, some distinctive features of the vertical profile of precipitable liquid water content (LWC) with considerable respect to rain rates (R) and radar reflectivity (Z) obtained in a tropical location are presented. Assessment of LWC allows applications in the specific area of flight icing severity, aviation safety as well as signals traversing through the atmosphere. The parameters were typically measured using vertically-pointing Micro Rain Radar (MRR) over a period of 2 years (2011-2012) at Akure, a tropical location of Nigeria. The radar scanned at every 10 seconds and integrated over one minute samples to reduce event logging error associated with the instrument. The vertical profile of the LWC typically reveals a prominent seasonal variation. However, majority of the LWC profiles has low LWC, less than 0.1 gm−3 while the maximum observed LWC is about 3.18 gm−3. A strong like hood relation was observed between the melting layer height and the LWC, with the LWC reaches peak at the considerable height of about 4160 m which coincides precisely with the freezing height level (rain height of ~4520 m) of the study location. Good correlation was also observed between the LWC and R in most of the heights considered. The results obtained will assist system engineers to assess the level of absorption, reflection and attenuation of electromagnetic signals as a result of precipitable LWC along the transmitting paths. The novelty of the present work is in the area of linking LWC and Z as against usual relation between Z and R.

Rainfall measurement using cell phone links: classification of wet and dry periods using geostationary satellites

ABSTRACTCommercial cellular telecommunication networks can be used for rainfall estimation by measuring the attenuation of electromagnetic signals transmitted between antennas from microwave links. However, as the received link signal may also decrease during dry periods, a method to separate wet and dry periods is required. Methods utilizing ground-based radar rainfall intensities or nearby link data cannot always be used. Geostationary satellites can provide a good alternative. A combination of two Meteosat Second Generation satellite precipitation products, Precipitating Clouds and Cloud Physical Properties, is employed to decide whether a 15-min time interval for a given link is rainy or not. A 12-d dataset of link-based rainfall maps for the Netherlands is validated against gauge-adjusted radar rainfall maps. Results clearly improve upon the case when no wet–dry classification is applied and thus the method shows potential for application to large areas of the world where the other methods cannot be applied.

Composite electroplating to enhance the GMI output stability of melt-extracted wires

Impedance output stability of Co-rich amorphous wires depends largely on the wire-terminal-connection, which can be accomplished by composite electroplating towards a robust sensor application. The present experimental results indicated that Ni/Cu composite layer composed of Ni, Cu plating and passivating treatment show a homogeneous microstructure, and excellent surface wettability, weldability and thermal expansion coefficient matching under variable temperature of wire-terminal-connecting. The properties of composite electroplated layer are mainly influenced by cathode current density, electroplating time and electrolyte temperature. The inhomogeneous distributed clustering-regions, disproportionated reaction, tendency of hydrogen brittleness and crack have been reduced by optimized coactions of intermolecular Van der Waals force, inner diffusion and mechanical bonding of electroplated layer. Therefore, the wire-terminal-connection is able to effectively improve impedance output stability by minimizing the disturbance of stray capacity, decreasing radio-frequency wave emission and electromagnetic signal attenuation, and suppressing the destabilization or concussion.

Improving the performance of an RF resonant cavity water-cut meter using an impedance matching network

In multiphase flow measurement, one of the most challenging issues is to define an adequate technology for a specific scenario, taking into account the measurement accuracy, implementation feasibility and costs. The electromagnetic technology based on resonant cavities is often employed in water-cut meters to measure two-phase flows such as water/oil and water/gas mixtures. The main disadvantage of this technology is the electromagnetic signal attenuation that occurs as the water content decreases. This undesirable behavior is amplified due to the impedance mismatch between the sensor ports and the transmitter/receiver modules. This paper presents a study to implement an impedance matching network in order to improve the instrument performance. Impedance matching networks were built, taking into account the matching for a 100%, 50% and, also, for the worst case of 0% of water fraction where there is a significant signal attenuation. The implemented networks improved the signal amplitude ratio between the first resonant mode and the other modes, increasing the identification accuracy of the first resonance peak.

Microwave Frequency Characteristics of Magnetically Functionalized Carbon Nanotube Arrays

This paper reports the results of a comprehensive study of the interaction of electromagnetic radiation (EMR) of the wide frequency range (8-12, 26-37, and 78-118 GHz) with arrays of vertically aligned and disordered carbon nanotubes (CNTs) which have been obtained by the floating catalyst chemical vapor deposition method. The obtained nanotubes represent a composite of multiwall CNTs with encapsulated magnetic nanoparticles of iron phases, i.e., magnetically functionalized nanotubes (MFCNTs). MFCNTs were formed on silicon substrates, and disordered arrays in the form of powder were obtained by separating the MFCNT arrays mechanically from the walls of the quartz reactor. The frequency dependences of the reflection and transmission coefficients of EMR of MFCNTs of two types were investigated. The high electromagnetic shielding efficiency (40 dB) of MFCNTs associated with the reflection of electromagnetic waves was detected. Possible mechanisms of attenuation of electromagnetic signals by aligned and disordered MFCNTs were discussed.

Experimental Investigation of the Electromagnetic Signal Attenuation Characteristics of the Partial Discharge Laboratory at Jadavpur University

Electromagnetic interference is becoming an increasing concern, because of the high intensity of surrounding electromagnetic waves, mainly arising from communication signals and also due to widespread use of equipment that operates at radio frequencies. As a consequence, sensitive data acquisition equipment suffers from erroneous results. Operating such instruments in a suitable shielded environment can significantly reduce this electromagnetic interference. But to achieve good shielding in practice, construction-related problems are to be faced, especially in large spaces, where a single metal plate cannot cover the whole area. Unless special care is taken, electromagnetic waves can penetrate through the gap in the joints and defects like drill holes reducing the shielding effectiveness. Also, a single layer of shielding is not always effective as the quality deteriorates drastically even due to minor constructional defects as mentioned above. This paper describes real-life experiences, step-by-step, in the shielding of a spacious insulation diagnostic laboratory (with a target of at least 55 dB signal attenuation), firstly using a good conducting material, using two different methods for joining the sheets, and ultimately constructing a second layer of shielding using a magnetic material. To study the attenuation behavior of the laboratory with respect to electromagnetic waves, a device for the relative measurement of surrounding electromagnetic signal strength is developed. The signal levels are measured initially outside and then at different places inside the shielded laboratory. The results presented in this paper show (1) the variation of attenuation characteristics inside the shielded laboratory due to different methods adopted for joining the shielding sheets using a good conducting material, (2) the effect of a second shielding layer in the form of a box that was constructed using a magnetic material and placed inside the laboratory and (3) the improvement in attenuation behavior after the actual construction of the second layer of shielding using a magnetic material.

Energy and Soil-Moisture Effects on Nonlinear Deformation Associated with Near-Surface Seismic Reflection Sources

The ability to collect seismic-reflection data in the upper [Formula: see text] of the subsurface (ultrashallow seismic reflection: USR) is important because it offers an alternative to ground-penetrating radar in regions exhibiting high attenuation of electromagnetic signal. Previous work has demonstrated that the critical controllable factors in obtaining USR data are dense spatial sampling and high [Formula: see text] frequency content. The frequency content is strongly controlled by the characteristics of the sources used to generate the seismic energy. Qualitative experiments have indicated that the higher-energy near-surface seismic reflection projectile sources lack some of the high-frequency energy exhibited by smaller-energy sources. In addition, soil moisture content has been shown to be an important variable in the frequency content of data even if the same source is used. In both cases, the reduction in the frequency content of the data has been hypothesized to correlate with greater amounts of near-source, nonlinear deformation. A corollary of this hypothesis states that source energy and soil-moisture affect the amount of nonlinear deformation generated by near-surface seismic energy sources. As an initial test of this corollary, experiments have been conducted in a controlled laboratory setting to quantitatively determine the relationship between source energy, soil-moisture conditions, and the amount of near-source, nonlinear deformation. Projectile sources with different energy (ammunition) were fired into a sand pit having varied moisture content, and the resulting voids were filled with plaster. The volume of the casts (representing the most substantial region of nonlinear deformation) was then measured. Results indicate that source energy and soil moisture have a direct correlation with the amount of near-source, nonlinear deformation.