Emission Of Electromagnetic Waves Research Articles

Ionising Radiation in Non-destructive Testing, Part 1 Types of Radiation used for Radiographic Testing – Basic Properties and Mechanism of Image Recording

Electromagnetic radiation, which is a special example of the electromagnetic field, has been present in the universe since its creation. Examples of radiation include radio waves, X-rays, and visible light. Depending on the frequency of the emitted electromagnetic wave, it can be ionising or non-ionising. Ionising radiation, due to its ability to penetrate matter, is oft en used in many areas of life. In industry, it is used for diagnostic purposes, e.g. in radiography.

Development of multiscale Fe/SiC–C fibrous composites for broadband electromagnetic and acoustic waves absorption

The explosive development of wireless communication devices and modern electronic machines raises concerns about potential human health threats from their extensive emission of electromagnetic waves (EMW) and acoustic noise. However, the insufficient lossy medium, monotonous structure, and large fiber diameters limit the broadband EMW and noise absorption of traditionally used fibrous materials. Here, we developed electro-spun Fe-doped and SiC nanoparticle-loaded carbon fibrous membranes (Fe/SiC–C) and their multiscale composites for effective broadband EMW and acoustic waves absorption performance. The Fe/SiC–C fibrous membranes show an excellent EMW absorption bandwidth (EAB) of 6.98 GHz at a thickness of 2.45 mm. Integrating a macroscale double-layer periodic cuboid design, we fabricated Fe/SiC–C fibrous metastructure composites that exhibit broadband EMW absorption with EAB of 15.2 GHz ranging from 2.8 GHz to 18 GHz at a total thickness of 8.45 mm. Additionally, using a simple roll-up method, we assembled the Fe/SiC–C fibrous membranes into a bulk sound absorber with a superior noise reduction coefficient (NRC) of 0.57 at a thickness of 30 mm. The multiscale development of carbon-based fibrous composites enables their potential application to electromagnetic and acoustic waves absorption.

Interaction of two-frequency electromagnetic waves with anisotropic media over hydrocarbon accumulation

The article analyzes the interaction of two-frequency electromagnetic waves with anisotropic media over hydrocarbon accumulation. The behavior of the real component έ3 of the dielectric permittivity tensor is investigated. The choice of signal characteristics is based on the use of different electromagnetic wave emission sources with amplitude and frequency ratio coefficients in the modes of powerful low-frequency and high-frequency signals. The dielectric permittivity tensor component έ3 as a function of dielectric permittivity and frequency of sounding signals was analyzed. Sounding modes of anisotropic media over hydrocarbons are recommended to identify the medium over the deposits and increase the accuracy of determining the boundaries of hydrocarbon accumulation. The obtained results of the research can be used in prospecting geophysics.

Simulation of Negative and Positive Corona Discharges in Air for Investigation of Electromagnetic Waves Propagation

Corona discharge, as one of the partial discharge (PD) modes, emits electromagnetic (EM) waves in the ultrahigh frequency (UHF) range. In order to study the behavior of the EM waves emitted from a PD source, a comprehensive PD source modeling method should be employed that takes into account the essential processes involved in the formation of that. In this article, a drift- and diffusion-based model is presented to simulate the corona discharges in the positive and negative voltages to investigate the differences between these two types of corona and their characteristics in terms of the EM waves’ propagation. This modeling tool includes ionization, attachment, and photoionization source terms as necessary phenomena to form the discharge. The results are analyzed for both types of coronas in the UHF range, and the differences between them are shown. Experimentally measured corona discharges using a high-frequency current transformers (HFCTs) and a monopole antenna probes are compared with the simulation current signals in the time and frequency domains, with promising results in terms of rise time and amplitude of the signal.

GPR surveys in enclosed underground sewer pipe space

To identify voids around underground concrete sewer pipes, a few studies have introduced conducting in-pipe Ground Penetrating Radar (GPR) inspection systems along the pipes. However, less research has focused on studying the implications of emission, propagation, and reception of electromagnetic waves in the enclosed environment of sewer pipes and their subsequent impact on the resulting radargrams. We defined simulation scenarios where we examine the influence of longitudinal and rotational survey types, antenna frequency, air–gap between antenna and sewer wall, antenna separation, and pipe wall’s mirroring effect on the resulting radargrams. Our results encourage practical considerations for designing in-pipe GPR surveys and outline the subsequent steps for automating the in-pipe GPR surveys.

Electromagnetic Interference Shielding Effectiveness of Natural and Chlorobutyl Rubber Blend Nanocomposite

The science and technology of electrical equipment for communication experience a rapid growth rate. However, the unwanted interference of electromagnetic waves of different electronic devices brought serious anxiety about human health as well as the lifetime and performance of the systems. To combat these consequences, we need to lessen the electromagnetic wave emission by making our devices more noise-sensitive. Herein, we incorporated carbon nanotubes (CNTs) at different ratios into natural rubber (NR) and chlorobutyl rubber (CIIR) to achieve shielding efficiency, along with carbon nanofibers (CNFs), nanoclay (NC), and carbon black (CB) to manipulate EMI shielding performance. The blend of CIIR/NR in a 70/30 (w/w) ratio also mixed with CNT, CNF, CB and NC. The effect of different fillers and their concentration/combination was analyzed by UV spectroscopy, demonstrating an absorbance peak in CIIR in 320 nm. From FTIR spectroscopy, it was evident that CIIR/CNT (5 phr), NR (30 wt.%)/CIIR (70 wt.%)/CB (5 phr), and NR (30 wt.%)/CIIR (70 wt.%)/CNT (5 phr) new bonding signatures were detected. The dielectric spectroscopic analyses were reflected in dielectric loss, dielectric permittivity and AC conductivity, where NR (30 wt.%)/CIIR (70 wt.%)/CB (5 phr) blend nanocomposite with 5 dB showed significantly higher EMI shielding performance compared to CIIR/CNT (5 phr) and CIIR/CNF (5 phr) with 29 and 15 dB, respectively. The greater the concentration of nanofiller, the lower the electromagnetic interference (EMI) shielding, i.e., CIIR/CNT (10 phr) with 15 dB (≈−48% dB), but with more agglomeration. Surprisingly, even a combination of fillers did not lead to higher EMI performance, such that CIIR/CNT (5 phr)-CB (20 phr) showed an EMI shielding value of 59 dB.

Excitation and detection of coherent sub-terahertz magnons in ferromagnetic and antiferromagnetic heterostructures

Excitation of coherent high-frequency magnons (quanta of spin waves) is critical to the development of high-speed magnonic devices. Here we computationally demonstrate the excitation of coherent sub-terahertz (THz) magnons in ferromagnetic (FM) and antiferromagnetic (AFM) thin films by a photoinduced picosecond acoustic pulse. Analytical calculations are also performed to reveal the magnon excitation mechanism. Through spin pumping and spin-charge conversion, these magnons can inject sub-THz charge current into an adjacent heavy-metal film which in turn emits electromagnetic (EM) waves. Using a dynamical phase-field model that considers the coupled dynamics of acoustic waves, spin waves, and EM waves, we show that the emitted EM wave retains the spectral information of all the sub-THz magnon modes and has a sufficiently large amplitude for near-field detection. These predictions indicate that the excitation and detection of sub-THz magnons can be realized in rationally designed FM or AFM thin-film heterostructures via ultrafast optical-pump THz-emission-probe spectroscopy.

Study of the radiation pattern of a rectangular horn antenna in the operation of multimode propagation of electromagnetic waves

The object of research in the work is the process of radiation of electromagnetic waves and the directional properties of a rectangular horn antenna in a multimode operation. The existing problem is that in practice when developing and researching horn antennas, only the single-mode mode of their operation is taken into account. The fundamental mode of the rectangular waveguide that feeds this horn antenna is chosen as the base mode of the emitted electromagnetic wave. Radiation of higher types of electromagnetic waves is not taken into account. To take into account the impact of higher types of electromagnetic waves on the directional properties of a rectangular horn antenna, it is proposed to investigate a multimode mode consisting of three types of magnetic waves H10, H20, and H30. Horn antennas have high-quality wide-range properties and make it possible to obtain a maximum frequency coverage ratio of 1.5–1.8. In this paper, the directional properties of a rectangular horn antenna are determined by the example of calculating and modeling normalized radiation patterns of a standard horn-type for a wide frequency range with an average frequency of 12 GHz and a frequency overlap factor of 1.67. It has been established that when emitting three higher types of waves, it is possible to simultaneously improve the characteristics and directional properties of a horn antenna by changing the amplitude of each component of the constituent waves of electromagnetic radiation. The work aimed to study the normalized radiation patterns of a rectangular horn antenna to improve its directional properties. It was found that with increasing frequency, starting from the middle frequency of the operating frequency range, the radiation pattern of a rectangular horn antenna expanded. That is, the opening angle increased in the direction of the main radiation, with a decrease in the radiation amplitude, the level of the side and rear lobes increased, which leads to a deterioration in the characteristics of the horn antenna. For the selected geometric dimensions of the horn antenna in the frequency range of 12–12.5 GHz in the multimode mode, it was possible to provide almost the same beam width in the horizontal and vertical planes at the level of 13.2–13.6°.

An Assessment on Earthquake Precursory Signals for Applications of Monitoring and Mitigation Strategies

Forecasting earthquakes entails the existence of time-dependent processes that are dependent on changing conditions deep inside the Earth's crust prior to the occurrence of major seismic activity. Mechanical variables, such as precursory ground deformation and earlier seismic events, have long been the focus of seismology research. The purpose of this review is to acknowledge that there have been numerous reports of a variety of precursory phenomena, including the emission of electromagnetic waves ranging from ultralow frequency (ULF) to visible (VIS) and near-infrared (NIR) light, the emission of radon gas, various electric and magnetic field anomalies, and unusual animal behaviour. Earthquake prediction research has been going on for almost a century with no obvious success.

Seasonal Impact on 3D GPR Performance for Surveying Yedoma Ice Complex Deposits

Ground-penetrating radar (GPR) is a popular geophysical method for imaging subsurface structures with a resolution at decimeter scale, which is based on the emission, propagation, and reflection of electromagnetic waves. GPR surveys for imaging the cryosphere benefit from the typically highly resistive conditions in frozen ground, resulting in low electromagnetic attenuation and, thus, an increased penetration depth. In permafrost environments, seasonal changes might affect not only GPR performance in terms of vertical resolution, attenuation, and penetration depth, but also regarding the general complexity of data (e.g., due to multiple reflections at thaw boundaries). The experimental setup of our study comparing seasonal differences of summertime thawed and winter- and springtime frozen active layer conditions above ice-rich permafrost allows for estimating advantages and disadvantages of both scenarios. Our results demonstrate major differences in the data and the final GPR image and, thus, will help in future studies to decide about particular survey seasons based on the GPR potential for non-invasive and high-resolution investigations of permafrost properties.

Investigation of the Effects of Pollution Caused by the Emission of Electromagnetic Waves on Human Health

Electromagnetic force, despite its useful efficiency and achievements, if not controlled and managed, is very dangerous for humans and will have irreversible effects that will remain even after thousands of years. Telecommunication devices such as mobile phones, cordless phones, VHF and SSB wireless and radar .... emit electromagnetic waves that when these waves collide with the living tissue of the body, cause changes in them that They endanger life.
 Magnetic and electric fields are generated by power lines, electrical wires, and electrical equipment, and are the invisible power lines that exist around each device, and its power increases with increasing voltage. The electromagnetic field is generated by electrical appliances such as personal computers, televisions, refrigerators, etc., as well as high-voltage power lines. The electromagnetic field disrupts the nervous system and the growth and development and repair of cells, leading to unknown diseases such as cancers, brain tumors and infertility in humans. Therefore, people who are exposed to such fields frequently and for a long time, as well as people working in the electrical and telephone industries, TV repairmen and welders are more vulnerable. Therefore, we must create a suitable environment for work and activity by installing carcinogen control devices in the workplace and identifying the sources of electromagnetic radiation production, observing safety points in the workplace and, if possible, using equipment that has the least amount of electromagnetic waves.

Materials and Devices for Engineering of Thermal Light: feature issue introduction

Thermal radiation describes the emission of electromagnetic waves from hot objects. Although the basics of thermal radiation have been well understood for more than a century, engineering of thermal radiation is an active research field, in part because of applications to energy harvesting, lighting, and thermoregulation. The rapidly evolving research base sits at the intersection of materials science, photonics, and thermal physics. In eight research papers and one opinion paper, this feature issue of Optical Materials Express advances the multidisciplinary field of engineering of thermal light.

Ground penetrating radar for real time surveying of soil as bioremediation precursor

GPR is a non-destructive method based on the emission and reception of electromagnetic waves generated by a bowtie antenna, of 400 MHz, in our case. The soil conductivity influences the propagation of electromagnetic waves, thus any inhomogeneity as water lens, chemical pollution, soil texture, buried objects modify the signal scattered on them and recorded by GPR tools. One of the potential advantages of GPR is that it is able to quickly analyses the presence in the underground of various inhomogeneities without having to come into contact with the ground and measures the time interval between pulse generation and reception, the results being presented in B-scan and linescan representation. Combining and processing the received signals, the results show as a map with emphasized watering regions. This paper presents the results of a case study where it was determined the effectiveness of GPR technology in detecting water content as well as the presence of water holes in airport runway draw. Further investigations will include the use of GPR together with electromagnetic induction method in order to make data fusion and increase the probability of detection.

Emission of electromagnetic radiation due to spin-flip transitions in a ferromagnet

We theoretically analyze the probability of electromagnetic wave emission due to electron transitions between spin subbands in a ferromagnet. Different mechanisms of such spin-flip transitions are considered. One mechanism is electron transitions caused by the magnetic field of the wave. Another mechanism is due to the Rashba spin–orbit interaction. While the two mentioned mechanisms contribute in a homogeneously magnetized ferromagnet, there are two other mechanisms that occur for a non-collinearly magnetized medium. The first mechanism is known and is due to the dependence of the exchange interaction constant on the quasimomentum of the conduction electrons. The second one is due to the minimal coupling. It follows from the connection of spin and spatial degrees of freedom in any non-collinearly magnetized medium. We study these mechanisms in a non-collinear ferromagnet with a helicoidal magnetization distribution. Estimations of the probabilities of electron transitions due to different mechanisms are made for realistic parameters, and we compare the mechanisms. We also estimate the radiation power and the threshold current in a simple model in which spin is injected into the ferromagnet by a spin-polarized electric current through a tunnel barrier.

Multifunctional Nanocellulose/Carbon Nanotube Composite Aerogels for High-Efficiency Electromagnetic Interference Shielding

Bio-based specialized components have emerged as a promising trend to limit the use of petroleum derivatives. Conversely, the current use of electronic systems has conditioned the emission of electromagnetic waves that interfere with high-precision devices and harm human health. Thus, robust, ultralight, and conductive nanocellulose-based aerogels paired with carbon nanotubes appear as an electromagnetic interference (EMI) shielding biomaterial to reduce the dispersion of microwaves emitted or received from a device. This study proposes a reliable aerogel system to deflect radiation by integrating TEMPO-oxidized cellulose nanofibrils, cationic cellulose nanocrystals, and sodium alginate, with carbon nanotubes at various concentrations. After inducing gelation, the aerogels were obtained by freeze drying. According to zeta potential and FTIR analysis data of nanocellulose, the aerogel frame was induced by electrostatic attraction and hydrogen bonds between the cellulosic matrix and the nanofillers. Finally, lightweight (density < 0.075 g/cm3), highly porous (porosity > 95.47%), conductive (up to 26.2 S/m), mechanically resistant, and EMI-protective aerogels were obtained, proving their potential to be used as green and lightweight shielding elements against electromagnetic radiation.

Observational properties of peculiar core-collapse super-novae producing r-process elements

We investigate the effects of r-process elements on the electromagnetic wave emission from peculiar core-collapse supernovae. We perform a series of radiative transfer simulations based on one-dimensional hydrodynamical explosion models. Varying the mass of 56Ni and r-process nuclei, we examine the effects of r-process elements on the light curves. The 56Ni-powered explosion models with a large amount of r-process-rich material show redder color because the high opacity of r-process elements suppresses the emission at shorter wavelengths. Comparing the results with the color of observed super-novae, we find that the upper limit for the production of r-process elements is 0.1M ⊙ for 56Ni-powered supernovae.

Creation of functional heat radiation surface by surface texturing

Industrial interest in thermal management is rapidly increasing due to the increase in the amount of heat generated by semiconductor devices as their performance improves in terms of miniaturization, higher power output, and higher density. Radiation of heat from a material surface is a phenomenon of electromagnetic wave emission, and the wavelength of the emitted electromagnetic wave varies with temperature according to Planck's law. In this paper, we aim to create functional heat radiation surfaces that can enhance heat dissipation performance in a specific temperature range by controlling the wavelength range of electromagnetic waves emitted from the material surface. Micro-cutting and ultrashort pulsed laser machining were used to fabricate various microstructures and their effects on heat radiation were investigated. It was found that the combination of a groove structure with an electromagnetic wavelength size and a sub-micrometer size groove structure can provide a temperature selectivity that increases the radiation flow in a specific temperature range.

ФИЗИЧЕСКИЕ ПРОЦЕССЫ В ИОНИЗОВАННОЙ ЛАЗЕРНЫМ ИЗЛУЧЕНИЕМ АТМОСФЕРЕ ПРИ СОЗДАНИИ ЛИНИИ РАДИОСВЯЗИ

The results of studies of ionization processes in the atmosphere that occur under the action of laser radiation make it possible to consider the possibility of using directed laser beams for location or formation of a communication channel. To do this, with the help of laser radiation in the atmosphere, a channel with a weakly ionized wall is formed, into which radio emission is introduced. The mini mum electron concentration Ne in the ionized channel, which ensures the reflection of the transmitted electromagnetic wave, depends on its frequency. If the frequency of electromagnetic radiation propagating in the channel is less than the frequency of plasma oscillations in the medium, then the waves are completely reflected from the ionized layer. In the range of long waves (1000-3000 m), the effect of self-radiation of plasma centers can be used to transmit information. By changing the dimensions of the plasma source in space, by modulating the laser radiation, it is possible to vary the frequency and amplitude of the emitted electromagnetic waves in a given range. The main mechanisms of creation of weak ionization channels in the atmosphere by laser radiation are considered. A scheme for the transmission of electromagnetic energy is proposed and its parameters are calculated. A variant of electromagnetic energy transfer by creating a plasma mirror in the atmosphere is considered. The frequency, duration, and energy of laser pulses necessary to create weak ionization channels in the atmosphere and ionosphere are estimated. The calculations and experiments carried out showed that an IR laser sub nanosecond radiation source with a pulse repetition rate of 108 Hz and providing a breakdown or pre-breakdown ionization mode can be used to transfer electromagnetic microwave energy in the atmosphere. It has been established that in the atmosphere it is possible to use both the breakdown mode and the pre-breakdown mode for generating and transmitting long-wave and microwave electromagnetic radiation. It is shown that in the pre-breakdown mode of aerosol ionization, anomalous scattering on plasma particle halos may occur due to the formation of plasmons, which increase the scattering intensity by 2-3 orders of magnitude.

In Vivo Activity Of Medications In Different Dosage And Ultrahigh Dilutions

Biological activity of medical remedies varies depending on the dosage of the medicinal substance. As we analyze the results of the medicinal effect we can determine three areas of its effect. First of all, this is a therapeutic area where its dose-dependent medical effect is demonstrated. When a certain amount of drug in the body it exceeded this causes transition to the toxic area where every medicine causes certain pathological manifestations. Significant decrease of the drug dose demonstrates the area of no effect on the body. At the same time similar body reaction can be observed with homeopathic remedies in ultrahigh dilutions. Classical definition of a dose as an amount of substance introduced into the body is not suitable for homeopathic remedies that often don’t have drug substance molecules at all. The presence of areas of different reaction is explained by the effect of electromagnetic wave emissions of drug substances. It is known that molecules of all medicinal substances have certain frequencies that come into resonance with different body structures, including genes that have similar oscillatory characteristics. This causes expression of certain genes and increase of their activities. Increase of an allopathic substance dose causes voltage increase it its wave and consequently an increase of the effect on the genes. However overdose causes hyperstimulation and exhaustion of the gene under expression and consequently pathological symptoms develop. On the other hand a dose too small cannot stimulate gene activity and this causes a lack of medical effect. As demonstrated by long-term studies, the activity of potentiated remedies (in ultrahigh dilutions) is related to development of coherence. Coherence is a phasic shift of the medicinal wave that occurs with potentiation of a remedy. As the potency is increased, every step, i.e. coherent wave shift decreases, thus increasing the probability of exact coincidence of the drug and gene waves and their contraposition to the wave of a xenobiotic. Wave shift by have the phase of a xenobiotic wave makes them opposite in terms of amplitude. They begin to damp each other and thus pathogenic effects of a xenobiotic are neutralized. In such a way, drug activity on the body is determined by wave characteristics of the medicinal substance molecules. Activity of allopathic medications depends on the dose, e.g. the number of drug substance molecules. Activity of homeopathic medications depends on the degree of their potentiation.

Research of a Fractal Microstrip Antenna Based on the Modified Minkowski Curve of the Second Iteration

Evolving telecommunications systems require modern antennas with improved performance. The creation of miniature antennas with a high gain, multi-band properties and defined polarization is an urgent task. New challenges in the reception and emission of electromagnetic waves are being solved in different ways. The use of fractals in the construction of antennas is becoming widespread. This article presents the results of a study of fractal microstrip antenna of the second iteration based on the Minkowski geometry. The main parameters such as the reflection coefficient, directivity and efficiency are described. Resonance frequencies and directional patterns at these frequencies as well as bandwidths are shown. Conclusions concerning the possibility of using this type of antenna in various applications are drawn.