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Heaviside reformulated the Maxwell equations because he considered that electromagnetic fields and waves have duality. As a result of the reformulation, the Poynting vector was obtained. When the variations of an electromagnetic field propagate in space as waves, this wave is referred to as an electromagnetic wave. The Poynting vector represents the traveling direction of the electromagnetic wave. In this Session, we reexamine electromagnetic fields and waves by focusing on the relationship between the Poynting vector and the duality. According to Wikipedia, no current flows in a vacuum because there are no electrons or electric charges. However, this seems to be incorrect, and the current I(x) given by rotH = I(x) flows in a vacuum. Moreover, a voltage V(x) given by rotE = -V(x) is generated because the magnetic field is the dual of the electric field and the current is the dual of the voltage. As a result, the presence of a coil in a vacuum is expressed by rotE = -V (x) = -∂B I ∂t = - pLI (x). Namely, the Maxwell equations indicate that "self-induction can occur everywhere in the atmosphere", as described by Heaviside in the book written by Nahin. Moreover, a capacitor in the atmosphere, including a vacuum, is also given by an equation because it is the dual of the coil. Thus, electromagnetic waves have physical properties of circuit elements including coils and capacitors, which are different from those of lines of forces, such as lines of electric and magnetic forces. The physics of electromagnetic waves is included in classical physics but is different from Newtonian mechanics and uses complex numbers. [ABSTRACT FROM AUTHOR]

Perovskite shines as a top contender in the realm of electromagnetic waves (EMW) absorption, owing to its unique physical properties, structural characteristics, and multifunctionality. However, it is still a huge challenge to synthesize high-performance EMW absorbing perovskite materials with environmental-friendly and sustainable processes, despite the simplicity of the perovskite preparation procedures. To address this issue, a facile solvent-free method was developed in this study for CH 3 NH 3 PbI 3 (MAPbI 3), then introduced carbon nanotubes (CNTs) and subsequently prepared MAPbI 3 /CNTs (MC) composites using a simple procedure. The frequency, thickness, reflection loss (RL), and effective absorption bandwidth (EAB) of MC for EMW absorption were systematically investigated by adjusting the filling amount and component ratio of MC. It is interesting to find that the as-prepared MC composites always achieve high absorption intensities in X and Ku bands. Moreover, an appropriate amount of CNTs can further optimize the impedance matching of MC and promote the loss capability of MAPbI 3.With a loading ratio of 25 wt% and a mass ratio of 2:1 between MAPbI 3 and CNTs, the MC sample exhibits excellent absorption capability, achieving the lowest RL of −63.8 dB at 1.8 mm and the maximum EAB of 5.16 GHz at 1.69 mm. These findings contribute to the design and development of organic-inorganic halide perovskite absorbers with superior EMW absorption performances. This work aligns with green chemistry principles and achieves the simple and efficient preparation of MAPbI 3 /CNTs. The significant impact of the compound ratio and loading ratio on the wave absorption performance are analyzed. The synergistic effect between the two components greatly enhances MAPbI 3 /CNTs, enabling outstanding electromagnetic wave absorption. [Display omitted] • The study focuses on dielectric properties can enhance and popularize MAPbI 3 /CNTs application in the field of absorption. • MAPbI 3 /CNTs composites are prepared by a solvent-free method. • MAPbI 3 /CNTs composites have high-performance microwave absorption, especially in the X and Ku bands. • Composites can still maintain the effective bandwidth at 4–5 GHz and achieve the lowest reflection loss of −63.8 dB at 1.8 mm. • This work develops the application potential of MAPbI 3 in the field of absorption other than solar cells field. [ABSTRACT FROM AUTHOR]

The microwave diagnostics of discharges occurring in an artificial cloud of charged water droplets created in an open air simulating the environment of thunderclouds is implemented. An artificial cloud with a droplet size of about 1 µm is opaque in the visible range, so intra-cloud discharges are not available for investigation by traditional methods in the spark discharge physics based on the registration of visible discharge radiation. Microwaves pass through such a cloud without noticeable attenuation, they interact only with the plasma of discharges occurring in the cloud. The probing microwave radiation had a wavelength of 8 mm. The attenuation of microwaves passed through the cloud was measured with temporary resolution of about 10 ns. The temporal characteristics of intracloud discharges were investigated. [ABSTRACT FROM AUTHOR]

Copyright of Latin-American Journal of Physics Education is the property of Latin-American Physics Education Network and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Graphite crucibles are widely used in induced crystal growth systems. This study examines the impact of temperature variation on the electrical conductivity of the graphite crucible and its influence on the temperature field and melt flow in a Czochralski germanium crystal growth furnace using the twodimensional finite element method. The in-depth analysis demonstrates that the temperaturedependence of electrical conductivity of the crucible is crucial in the growth process and the thermal field of the setup. Specifically, it is noted that temperature changes have a significant effect on the generation and distribution of induction heat, the temperature and melt flow field, the complex shape of the crystal-melt interface, as well as the stress and dislocations in the grown crystal. These findings highlight the intricate relationship between temperature, crucible conductivity, and the dynamics of the crystal growth process, providing insight into the subtle factors that impact the quality and properties of the resulting crystal. [ABSTRACT FROM AUTHOR]

In practice, the reflected EM signal cannot be clearly observed in GPR data due to the high water content and other reasons. However, the antenna coupling signal through the ground interface is dominated in all the GPR measurements. This direct coupling signal that travels through the ground interface is called a lateral wave. The properties of the lateral wave directly depend on the subsurface properties, especially electrical parameters. We have numerically analyzed a lateral wave and its velocity. Subsequently, the relationship between lateral wave and dielectric permittivity was determined by polynomial regression. Analytically, it is challenging to analyze a lateral wave due to the parameters that can influence wave propagation. Antenna characteristics, surface roughness, etc need to be considered. Numerically, we designed a GPR system with a subsurface layer and observed a lateral wave. This numerical analysis can give a chance to use a lateral wave for near-surface soil water content. This analysis gives a more precise estimation of surface water content. Moreover, we analyze the antenna height effect that influences radar signals. We numerically observed that the GPR signal is highly affected by antenna height. The antenna height effect depended on the wavelength of the applied electromagnetic wave. By adjusting the antenna height, the unobservable GPR signal can be clearly detected.

Advances in radar technology have driven efforts to develop effective countermeasures. Plasma is recognized as a highly effective medium for absorbing electromagnetic waves. Recent research has focused on enhancing plasma element performance. This paper achieved ultra-high-density, low-pressure cold plasma with a density of 1.15 × 1012 cm−3, surpassing similar studies by more than an order of magnitude. Tungsten electrodes with high-curvature spiked structures were invented to replace traditional iron–nickel alloy electrodes, increasing plasma density by 88.2% under the same conditions. Lightweight and cost-effective tubular and annular ultra-high-density, low-pressure cold plasma devices were developed, demonstrating exceptional performance in electromagnetic wave absorption, plasma transient antennas, and radar stealth technology. The influence of plasma on electromagnetic waves and its numerical relationship were analyzed. By measuring the radar cross-section (RCS), the reduction in radar detection rates was quantified. The results show that the ultra-high-density cold plasma devices exhibit very low intrinsic RCS values, suitable for plasma antenna applications. The array of plasma elements generates a large-area high-density low-pressure cold plasma. This plasma effectively reduces the radar cross-section (RCS) of metallic equipment in the S and C bands and shows attenuation in the X band. These effects highlight the superior characteristics of plasma technology in electronic warfare. This exploratory research lays the groundwork for further defense applications.

Since the discovery that Fe3O4 nanoparticle has intrinsic natural peroxidase‐like activity by Yan et al in 2007, mimicking native enzymes via nano‐engineering (named as nanozyme) pays a new avenue to bypass the fragility and recyclability of natural enzymes and thus expedites the biocatalysis in multidisciplinary applications. In addition, the high programmability and structural stability attributes of nanozyme afford the ease of coupling with electromagnetic waves of different energies, providing great opportunities to construct photo‐responsive nanozyme under user‐defined electromagnetic waves, which is known as photo‐nanozyme. In this concept, we aim to providing a summary of how electromagnetic waves with varying wavelengths can serve as external stimuli to induce or enhance the biocatalytic performance of photo‐nanozymes, thereby offering fascinating functions that cannot be achieved by pristine nanozyme. [ABSTRACT FROM AUTHOR]

When metal nanoparticles (MNPs) are illuminated with a monochromatic laser wave, the frequency of which is far from the plasmon frequency (the frequency of plasmon resonances), under certain conditions (depending on the frequency of the wave, its polarization, the size and shape of the MNPs), absorption of light by MNPs can be dominated by magnetic absorption (absorption caused by the magnetic component of the electromagnetic field of the light (laser) wave). This work is focused on studying the features of absorption caused by the influence of the magnetic component of laser radiation. This issue is rather poorly studied for MNPs of non-spherical shape. Therefore, how the shape of the particle manifests itself in its absorption of laser radiation (laser pulses) is one of the goals of our research. In this work, we will study the features of magnetic absorption of light (laser radiation) depending on the shape of the particles. In this paper, we will investigate the influence of spheroidal MNPs on this process. Calculations will be carried out using the kinetic equation method, because we will consider the case when the size of the MNP is smaller than the length of free path of the electron in the MNP. Note that the kinetic approach makes it possible to obtain correct results for the case when the size of the particle is greater than the length of the free path. For non-spherical MNPs, we have developed a theory that makes it possible to calculate the energy of magnetic absorption by a particle when it is irradiated with laser pulses. The dependence of magnetic absorption on the ratio of the radii of curvature of spheroidal MNPs and the vector of the magnetic field of an electromagnetic (laser) wave was constructed and theoretically investigated. An interesting result is the absorption of energy by a spheroidal MNP as its disco similarity increases. We now use to estimate the relative contributions of electric We and magnetic Wm absorption to the total absorption. For example, let us take a gold MNP’s, then ωp ≈ 5·1015 s –1, ν ≈ 1013 s –1, R = 3·10–6 sm, ω ≈ 2·1014 s –1 (carbon dioxide laser), ε' ≈ –600, ε' ≈ 30 we received the next ratio We/Wm ≈ 2. We can see that for the given set of parameters magnetic absorption is twice as large as electric. Obviously, for different parameters of the particle and a different frequency range electric absorption can be either larger or smaller than magnetic absorption. Hence, when studying the dependence of optical absorption by MNP’s on particle form, we must allow for both electric and magnetic absorption. For an asymmetric MNP’s (for example ellipsoidal particles), apart from everything else, the ratio of the electric and magnetic contributions to absorption (as fixed frequency) is strongly dependent on the degree of particle asymmetric and wave polarization. [ABSTRACT FROM AUTHOR]

The equivalence of paired serial functional equations of some problems of diffraction of waves by thin screens, of integral equations and of infinite set of linear algebraic equations is established. Two classes of solutions are considered: classical functions and generalized functions. The uniqueness of solutions of the paired equations is essentially used. [ABSTRACT FROM AUTHOR]

Fuchs functions are one of the solutions to one-dimensional wave equations and are expressed similarly to cascade matrices used in circuit theory. Because Fuchs functions are groups, they have the operation of multiplication but do not require the operation of addition. However, the operation of addition is possible for cascade matrices owing to their transformation. As 2 x 2 matrices, cascade matrices have the potential to lead to new mathematics. Moreover, the Maxwell equations are considered to be the equations of fields as well as those of electromagnetic waves. In this case, the phenomena of refraction and partial reflection should be describable by the Maxwell equations. Therefore, the equations of electromagnetic waves derived from the Maxwell equations are expected to be telegrapher's equations which are realized by coaxial cables. [ABSTRACT FROM AUTHOR]

Theoretical studies of dispersion, field, and, energy properties of guided modes in a waveguide based on a composite metamaterial in the infrared region of 1÷5 μm have been carried out. The consideration was carried out on the basis of the electromagnetic method (including the effective medium approximation) and an alternative method - 4×4 matrices. In both models, frequency regions corresponding to the propagation of bulk TE and TM modes were found in the dispersion spectra. It is shown that the use of the electromagnetic approach helps to identify the dispersion curves obtained using the 4×4 matrix method, i.e. establish their correspondence to a mode with a specific index and polarization. The advantage of the electromagnetic approach is its comparative simplicity, while the 4×4 matrix method requires large computational resources. The effectiveness of using the long-wavelength approximation within the framework of the electromagnetic approach for describing the considered guiding structures of a composite metamaterial has been confirmed. The results obtained can be used to create optical polarizers, filters, and polarization-sensitive waveguide-type switches based on a composite metamaterial. [ABSTRACT FROM AUTHOR]

In this article, we describe the analogy between some boundary value problems in electrodynamics and quantum mechanics, which evidently results due to the plane wave solutions of the associated wave equations and similar boundary conditions. As the first example, the reflection and transmission coefficients for normal incidence of plane electromagnetic waves on the interface of two dielectric media are compared with that for the one-dimensional step potential problem in quantum mechanics. In the second example, we take a problem from Griffiths's electrodynamics and discuss the analogy with a quantum mechanical problem. [ABSTRACT FROM AUTHOR]

In this work, for the first time, we have analyzed and compared the responses of polar mesosphere winter echoes (PMWE) and their summer counterpart, polar mesosphere summer echoes (PMSE), to high-frequency (HF) heating in terms of modulated characteristics (i.e., backscatter intensity reduction, recovery, and overshoot). Both PMWE and PMSE observations were from the same site (Tromsø, Norway; 69.6°N, 19.2°E) and radar (EISCAT [European Incoherent Scatter Scientific Association] very high frequency, 224 MHz). The heating patterns of both PMWE and PMSE were found to be similar; however, PMSE was more greatly affected by HF heating. Polar mesosphere summer echoes showed recovery and overshoot more frequently than did PMWE. In addition, the mean recovery and overshoot of PMSE were greater than those of PMWE. The associated electron temperature enhancement was estimated for both PMWE and PMSE and showed that, compared with PMWE, the electron temperature enhancement was more significant in PMSE. The strong heating effects on PMSE may be due to the considerable increase in electron temperature.

This study examines the characteristics of the electromagnetic waves that propagate through an unbounded space filled with a homogeneous isotropic chiral medium. The resulting characters are compared to those of the electromagnetic waves propagating through an achiral free space. To this goal, we form energy conservation laws for key bilinear parameters in a chiral case. Due to a nonzero medium chirality, conservation laws turn out to contain extra terms that are linked to the spin–orbit coupling, which is absent for an achiral case. In this way, we identified where the neat hierarchy exhibited by the achiral case among the key bilinear parameters is destroyed by a medium chirality. As an example, we took a plane wave for the chiral case to evaluate those bilinear parameters. Resultantly, the conservation laws for a chiral case are found to reveal inconsistencies among several bilinear parameters that constitute the conservation laws, thereby prompting us to establish partial remedies for formulating proper wave-propagation problems. Therefore, adequate applications of boundary conditions are found to be necessary after examining typical problems available from the literature.

Electromagnetic plasma waves related to nonuniform electron-ion and electron-positron-ion plasma in interaction with short pulse laser in the quantum state have been investigated. These investigations have been done in low-frequency approximation. In these two plasmas, the initial quantities of number density, streaming velocity, and external magnetic field are inhomogeneous. The investigations have shown that in the perpendicular direction, the amount of these initial quantities affects the wave velocities, their instability rate, and their gradients affect the waves, strongly. The behavior of the perpendicular waves has been analyzed for variation in these initial quantities and the investigations show that these behaviors are different in these two plasmas. In the parallel direction, the factor that most affects the waves is the ponderomotive force related to the laser, so an increase in this force cause to increase in the wave velocities and their instability rate. The dependence of the parallel waves on the initial quantities of the number density and streaming velocity is direct, and their reliance on the external magnetic field is through the ponderomotive force (presence of laser). The waves in this direction are not affected by the transverse gradients of the initial quantities. The plasma waves in both plasmas have also been affected by the quantum correction terms. It has been demonstrated that our resulting equations are in accordance with the references mentioned in the article.

In this paper, a finite cylindrical plasma waveguide is investigated as a plasma valve in the path of a non-dissipative cylindrical waveguide with metal walls. Theoretical simulation to investigate the effect of the main parameters of this plasma valve on the transmission coefficients and reflection coefficients of the symmetric modes is the main part of this paper. The transmittance coefficients of electromagnetic waves in each symmetric mode are introduced in terms of Henkel functions and ordinary Bessel functions, and the role of these functions in the purification of some modes is investigated. Taking into account the boundary conditions, the transmission coefficient of the output wave modes from the plasma valve are obtained. The diagrams of the mentioned coefficient versus the incident wave frequency, geometry dimensions and the type of the used plasma in the valve are studied.

Understanding the oxidative and thermal degradation of CO2 sorbents is essential for assessing long‐term sorbent stability in direct air capture (DAC). The potential degradation pathway of imidazolium cyanopyrrolide, an ionic liquid (IL) functionalized for superior CO2 capacity and selectivity, is evaluated under accelerated degradation conditions to elucidate the secondary reactions that can occur during repetitive absorption‐desorption thermal‐swing cycles. The combined analysis from various spectroscopic, chromatographic, and thermal gravimetric measurements indicated that radical and SN2 mechanisms in degradation are encouraged by the nucleophilicity of the anion. Thickening of the liquid and gas evolution are accompanied by 50 % reduction in CO2 capacity after a 7‐day exposure to O2 under 80 °C. To prevent long exposure to conventional thermal heating, microwave (MW) regeneration of the CO2‐reactive IL is used, where dielectric heating at 80 and 100 °C rapidly desorbs CO2 and regenerates the IL without any measurable degradation. [ABSTRACT FROM AUTHOR]

The adaptive backstepping control method of permanent magnet motor has the problems of complicated coordinate transformation process and high position tracking error. Based on this, an adaptive backstepping control method of permanent magnet synchronous motor based on RBF is proposed. According to the principle of electrical machinery, the electromagnetic wave and magnetic field data are obtained, and the mathematical model of permanent magnet synchronous motor is constructed. Under the condition of keeping the resultant magnetomotive force after coordinate transformation unchanged, the structure of motor torque neural network is established by RBF method, and the coordinate transformation process is optimized. Through the compensation control strategy, the adaptive backstepping control mode is designed to realize the adaptive backstepping control of permanent magnet synchronous motor. The simulation results show that the position tracking error of the proposed method is 4.549 mm when the running time is 7 s and 43.699 mm when the running time is 14 s, which proves that the adaptive backstepping control effect of the proposed method is better. [ABSTRACT FROM AUTHOR]

Copyright of Computer Measurement & Control is the property of Magazine Agency of Computer Measurement & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Reasonable design and optimization of the dielectric and magnetic properties of materials are important to achieve excellent electromagnetic wave (EMW) absorption capacities. Residual carbon (RC) derived from coal gasification fine slag-loaded hollow-spherical Fe 3 O 4 nanoparticles (Fe 3 O 4 NPs@RC) was synthesized via hydrothermal strategy. The chemical compositions, morphologies, structures, and electromagnetic parameters of the as-prepared RC and Fe 3 O 4 NPs@RC revealed that the phase components (RC and Fe 3 O 4 phases) and microstructure (hollow spherical and micro/nano blocks) were well modified by modulating the content of Fe 3 O 4. Such modifications result in variations in the hierarchical structure, defects, electromagnetic parameters, and EMW absorption performance. The Fe 3 O 4 NPs@RC composites (S1 and S2) exhibited superior EMW absorption capacity. The binary composite with an additive amount of FeCl 3 ·6H 2 O of 2.66 g (S2) exhibited the minimum reflection loss (RL min) of −32.6 dB at 2.0 mm and a broad absorption bandwidth (f e , RL less than −10 dB) of 4.64 GHz at a lower thickness value of 1.65 mm under a filler content of 40%. In addition, the ultra-broad f e reached 14.35 GHz, which contained the entire Ku, X, and C bands by easily regulating the thicknesses from 1.5 mm to 5 mm. A possible EMW absorption mechanism was proposed. This study offers an effective strategy for designing novel coal gasification solid waste-based materials for high-performance absorbers. [ABSTRACT FROM AUTHOR]

Temperature distribution in the metallic plate influenced by high frequency electromagnetic wave depends on thermal and electrical properties of the plate material. The goal of the paper is to present the significance of the temperature dependence of the electrical resistivity and its influence on the plate heating. A mathematical model of the problem was established and an analytical closed-form solution the problem was presented. The active power of the electromagnetic wave was calculated by Poynting vector. Temperature field was obtained by integral-transform technique. Numerical examples were presented for three different materials (copper, aluminum, and steel). Calculated results show the large influence of temperature dependent electrical resistance on heating of the metallic plate. [ABSTRACT FROM AUTHOR]

Copyright of Cotton Textile Technology is the property of Cotton Textile Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Dust particles and sand storms can cause attenuation and cross-polarization of electromagnetic wave propagation, especially at high frequencies above 10 GHz. Dust attenuation has been the focus of many research works, mainly with the deployment of a 5G wireless network in the FR-2 band (mmWave band, 23–53 GHz with TDD). This has led to the development of novel models to accurately predict and estimate attenuation. However, the existing review works have not adequately provided extensive taxonomies for these models to show the state-of-art and future research directions. This paper aims to bridge this gap by providing a comprehensive review of all electromagnetic scattering models in terms of their strengths, weaknesses, and applications. Lessons learned from the detailed survey have been stated and discussed extensively. Key findings from this review indicate that all the models developed were limited to the region where they were developed, with frequency and visibility levels as the two main parameters. The survey across regions showed no model was developed for Region 2, including the Americas, Greenland, and some of the eastern Pacific Islands. Among the dry regions of the globe, where dust and sand storms can occur either occasionally or frequently, it can be seen that only a few parts of these desert regions of Africa (Region 1) and Asia (Region 3) have been considered by authors for the development of prediction models for attenuation due to dust storms. Thus, this also shows the limitations of the overall deterministic models and presents the crucial need to develop new models or modify existing models to accurately predict dust attenuation in other regions, particularly in Africa.

Abstract Pathogenic viral infections have become a serious public health issue worldwide. Viruses can infect all cell-based organisms and cause varying injuries and damage, resulting in diseases or even death. With the prevalence of highly pathogenic viruses, such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), it is urgent to develop efficient and safe approaches to inactivate pathogenic viruses. Traditional methods of inactivating pathogenic viruses are practical but have several limitations. Electromagnetic waves, with high penetration capacity, physical resonance, and non-contamination, have emerged as a potential strategy to inactivate pathogenic viruses and have attracted increasing attention. This paper reviews the recent literature on the effects of electromagnetic waves on pathogenic viruses and their mechanisms, as well as promising applications of electromagnetic waves to inactivate pathogenic viruses, to provide new ideas and methods for this inactivation.

As a device for missile-borne system to transmit and receive electromagnetic waves, the functions of missile-borne antenna are becoming more and more abundant. The shared-aperture antenna can improve the aperture utilization rate of missile seeker and can avoid radiation interference between antennas. This paper proposes a low profile circularly polarized shared-aperture antenna for missile seeker antenna based on the theory of microstrip circular polari-zed antenna. More specifically, the sequential rotation feed technology is adopted for the rectangular microstrip antenna in the high-frequency C-band part, while the orthogonal double feed technology is adopted for the cross microstrip antenna in the low-frequency S-band part. The nested shared-aperture antenna structure is adopted to realize the design of shared aperture antenna of 63 mm×63 mm×1.574 mm. The reflection coefficient is less than -10 dB in the frequency bands of 4.87~5.13 GHz and 2.49~2.51 GHz. The relative bandwidth of high-frequency antenna is 8.1% and that of low-frequency antenna is 0.4%. The axial ratio of the two antennas in the maximum radiation direction at the center frequency is less than 3 dB. The experimental data show that the shared-aperture antenna designed and applied to the missile-borne antennacan significantly improve the aperture utilization of the missile seeker, and can also eliminate the deterioration of the radiation performances caused by the mutual coupling of antennas.

To study the frequency response characteristics of knitted fabric-based frequency selective surface (FSS), high-pass knitted fabric-based FSS were designed and prepared. The electromagnetic transmission characteristics were tested in a microwave anechoic chamber. The results show that weft-knitted fabric based FSS has high-pass and low-resistance electromagnetic properties. When the placement direction of the knitted fabrics and the polarization mode of electromagnetic wave are different, the frequency response characteristics are distinct. When the ratio of conductive yarns increases, the electromagnetic wave shield ability and breathability of knitted fabric based FSS are enhanced. The shielding ability of the fabric increases with the density, but the permeability of the fabric decreases. As the incident angle of electromagnetic wave increases, the electromagnetic wave component entering the fabric decreases, and the electromagnetic wave passing through the fabric decreases. Therefore, under the premise of wear comfort, the frequency response characteristics of knitted fabrics can be controlled and selective transmission of electromagnetic wave can be achieved by designing the structure and weaving parameters of knitted fabrics and adjusting the polarization mode and incidence angle of electromagnetic wave.

The problem of electromagnetic wave pressure on a thin conductive vibrator located in a rectangular waveguide is solved. Wave H10 falls on the vibrator. The vibrator is located perpendicular to the wide wall of the waveguide. The current in the vibrator arising under the action of the electric field of the wave is calculated. The current distribution along the vibrator is almost uniform. The current in the microwave range depends little on the vibrator conductivity. Two components of the magnetic field - longitudinal and transverse exist in the H10 wave. When these components interact with the current in the vibrator, forces arise, acting on the vibrator across the waveguide and along it. The magnitude of the longitudinal force is greatest when the vibrator is located in the middle of a wide wall. It is almost 2 times greater than the force acting on the vibrator in free space at the same average radiation intensity, When the vibrator length is close to half the radiation wavelength, the force is maximum. The transverse force is determined by the interaction of the current in the vibrator with the longitudinal component of the magnetic field in the waveguide. It is maximum when the vibrator is located at the distance of ¼ of the length of the wide wall from its middle. If the length of the vibrator is less than half the wavelength of the radiation, the force is directed towards the axis of the waveguide, otherwise - in the opposite direction. The possibility of using microwave radiation pressure to create micromachines and to control the position of the vibrator in space has been evaluated. This requires a radiation power of several watts.

Core–shell structures and interfacial polarization are of great significance to meet the diversified requirements of microwave attenuation. Herein, α -Fe2O3@MoS2 nanocomposites are fabricated via a simple two-step hydrothermal process, in which MoS2 nanosheets as the shell are self-assembled and α -Fe2O3 microdrums are used as the core to constitute a special flower-like morphology with core–shell structure. This structure can provide more interface contact to achieve strong interfacial polarization and possibly offer more multiple reflection and scattering of electromagnetic waves. Furthermore, the microwave dissipation performances of α -Fe2O3@MoS2 nanocomposites can be significantly improved through construction of core–shell structure and flower-like morphology, controlling the content of α -Fe2O3 microdrums and adjusting the filler loading ratios. This work proves that the as-synthesized nanocomposites achieve excellent effective absorption bandwidth and outstanding electromagnetic wave absorption capabilities due to their special interfaces, core–shell structures and good impedance matching conditions. Therefore, α -Fe2O3@MoS2 nanocomposites are expected to be a novel and desirable candidate for high-performance electromagnetic wave absorbers. [ABSTRACT FROM AUTHOR]

Nanocomposites containing components with semiconductor, ferroelectric, and ferromagnetic properties have attracted considerable attention of specialists due to the range of possible applications, including catalysis and electrocatalysis, electrode materials for solar and fuel cells, capacitors, electrical and biosensors, anti-corrosion coatings and much more. In recent years, both fundamental and applied interest in this direction of research is due to the possibility of creating a new type of controlled microwave devices and tools. The aim of the work is to develop methods for the synthesis of nanostructured NiCo composites based on BaTiO3 and TiO2, as well as to find the differences and regularities of their physicochemical properties. Two series of samples with different content of NiCo nanoparticles based on titanium oxide (TiO2) and barium titanate (BaTiO3) were obtained. NiCo particles were obtained by the method of chemical precipitation of nickel and cobalt carbonates in equal parts from a hydrazine hydrate solution at the temperature of 350 K. The results of X-ray phase analysis indicate the chemical purity of the obtained samples. The values of ε′, ε″ at a frequency of 9 GHz for the NiCo/BaTiO3 system are twice as high compared to NiCo/TiO2 for the corresponding values of the NiCo content, which is due to the higher values of ε′, ε″ of the initial barium titanate. Electrical conductivity of NiCo/BaTiO3 system changes by six orders of magnitude, which indicates the formation of a continuous percolation cluster of metal particles on the surface of dielectric BaTiO3 particles. The composites are heat-resistant up to 630K, as shown by the method of thermogravimetry and pronounced magnetic properties. The program for calculating frequency dependences of reflection and absorption coefficients in a complex form has been developed. EMF absorption for composites from the radiation frequency and the position of the minima of these characteristics, which agree satisfactorily with the experiment. The obtained composites can be promising components for obtaining composite systems and paints for protection against electromagnetic radiation. [ABSTRACT FROM AUTHOR]

The separation of tiles from buildings degrades the aesthetic appeal of buildings and may result in structural failure. Therefore, tiles should be inspected periodically. However, manual inspections are expensive and require qualified experts. In this study, voids corresponding to tile separation were detected in a concrete specimen using nondestructive inspection based on electromagnetic wave detection. Furthermore, wave reflection models of healthy and defective tiles were created, and the effects of the void plane size on the reflection of defective tiles were considered. The correlation between the void plane size and the reflection intensity difference integral value was verified through multilayer scanning using these models. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

To study the frequency response characteristics of high-pass woven fabric, samples with varying conductive grid structure, structure parameters, material conductivity, and electromagnetic (EM) wave parameters were prepared and measured by the shielding room method. Experimental results showed that conductive grid structure was effective in obtaining bidirectional shielding ability and conductive stripe structure had directional shielding property to the EM wave.. Depending on changing the ratios of dielectric and conductive yarns, structure parameters exerted influences on frequency response characteristics by affecting vertical inductances and horizontal capacities in the equivalent circuit. High-pass woven fabric with high-conductivity yarns could possess stronger shielding ability. Due to the different compactness in weft and warp directions after weaving, bidirectional grid structure fabrics showed distinct polarization selective characteristic as well as unidirectional structure fabric. When the incident angle of the EM wave increased, the incident component decreased and the transmittance became unstable. The experimental results were discussed in-depthbased on mechanism analysis, which could provide reference to the relevant research. [ABSTRACT FROM AUTHOR]

Nanocomposites containing components with semiconductor, ferroelectric, and ferromagnetic properties have attracted considerable attention of specialists due to the range of possible applications, including catalysis and electrocatalysis, electrode materials for solar and fuel cells, capacitors, electrical and biosensors, anti-corrosion coatings and much more. In recent years, both fundamental and applied interest in this direction of research is due to the possibility of creating a new type of controlled microwave devices and tools. The aim of the work is to develop methods for the synthesis of nanostructured NiCo composites based on BaTiO3 and TiO2, as well as to find the differences and regularities of their physicochemical properties. Two series of samples with different content of NiCo nanoparticles based on titanium oxide (TiO2) and barium titanate (BaTiO3) were obtained. NiCo particles were obtained by the method of chemical precipitation of nickel and cobalt carbonates in equal parts from a hydrazine hydrate solution at the temperature of 350 K. The results of X-ray phase analysis indicate the chemical purity of the obtained samples. The values of ε′, ε″ at a frequency of 9 GHz for the NiCo/BaTiO3 system are twice as high compared to NiCo/TiO2 for the corresponding values of the NiCo content, which is due to the higher values of ε′, ε″ of the initial barium titanate. Electrical conductivity of NiCo/BaTiO3 system changes by six orders of magnitude, which indicates the formation of a continuous percolation cluster of metal particles on the surface of dielectric BaTiO3 particles. The composites are heat-resistant up to 630K, as shown by the method of thermogravimetry and pronounced magnetic properties. The program for calculating frequency dependences of reflection and absorption coefficients in a complex form has been developed. EMF absorption for composites from the radiation frequency and the position of the minima of these characteristics, which agree satisfactorily with the experiment. The obtained composites can be promising components for obtaining composite systems and paints for protection against electromagnetic radiation. [ABSTRACT FROM AUTHOR]

To deal with the growing electromagnetic hazards, herein a Co@CuFe2O4 absorbing agent with excellent impedance matching at thin thickness was obtained via an innovative route of ball-milling assisted chemical precipitation and annealing. The as-prepared composite possesses excellent interface polarization ability due to sufficient contact between CuFe2O4 NPs and flat Co, and this compressed Co lamella can also provide sufficient eddy current loss. Moreover, the dipole polarization, electron hopping/conduction, and structural scattering also contribute to the broadband microwave absorption of the composite. Thus, the minimum microwave reflection loss achieves −35.56 dB at 12.93 GHz for 1.8 mm thickness, and the broadest efficient absorption bandwidth can reach 6.74 GHz for a thinner thickness of 1.72 mm. The preparation method reported here can be referenced as a new-type route to manufacture electromagnetic absorbers with outstanding performance. [ABSTRACT FROM AUTHOR]

This study examines the characteristics of the electromagnetic waves that propagate through an unbounded space filled with a homogeneous isotropic chiral medium. The resulting characters are compared to those of the electromagnetic waves propagating through an achiral free space. To this goal, we form energy conservation laws for key bilinear parameters in a chiral case. Due to a nonzero medium chirality, conservation laws turn out to contain extra terms that are linked to the spin–orbit coupling, which is absent for an achiral case. In this way, we identified where the neat hierarchy exhibited by the achiral case among the key bilinear parameters is destroyed by a medium chirality. As an example, we took a plane wave for the chiral case to evaluate those bilinear parameters. Resultantly, the conservation laws for a chiral case are found to reveal inconsistencies among several bilinear parameters that constitute the conservation laws, thereby prompting us to establish partial remedies for formulating proper wave-propagation problems. Therefore, adequate applications of boundary conditions are found to be necessary after examining typical problems available from the literature. [ABSTRACT FROM AUTHOR]

In this letter, we present some comments related to Pall's publication, in which Pall states that the electric field disappears after a few centimeters and that the magnetic field continues progressing within the studied material. [ABSTRACT FROM AUTHOR]

The rapid development of electromagnetic technology has been widely used in many fields. For example, the transmission of electromagnetic waves in extreme environments (such as sandstorms and haze) and the monitoring of particle composition in the atmosphere by using electromagnetic wave technology. The properties of particles, such as particle electrification, will affect electromagnetic wave scattering and directly affect the signal transmission quality and monitoring results. Based on the scattering characteristics of electromagnetic waves of charged particles, the effects of different particle composition, different electric quantity, different humidity and different particle numbers on electromagnetic wave propagation are studied in this paper. The multiple scattering of electromagnetic waves by the random distribution of multiple particles is studied, and the Maxwell equation is converted into the Foldy–Lax multiple scattering equation, and the numerical solution is carried out. The influence of charged particle clusters on the electromagnetic scattering is analyzed. The simulation and experiment show that the charge of particles has a great influence on the electromagnetic scattering near some frequencies. [ABSTRACT FROM AUTHOR]

Nonmagnetic ceramics are ideal microwave absorbing materials used in high-temperature and oxidizing environments. However, low-frequency absorbing properties of this material are rarely reported because low-frequency absorbing requires nonmagnetic materials to have much higher permittivity. In this research, a series of three-dimensional architectures formed by SiC nanowires with different microstructures felt were fabricated to address this issue. The morphology of the SiC nw (linear, bamboo-shaped, and worm-like) dominated by the VLS growth mechanism can be manipulated by the silicon vapor concentration, which is governed by the vaporization temperature of the mixed silicon source (Si and SiO 2) in different sintering processes. The spontaneously overlapped bamboo-shaped SiC nanowires in these felt enhance the permittivity and conductivity loss and produce multiple scattering effects on the incident EM waves, thus increasing the low-frequency wave absorption ability. The RL min of the bamboo-shaped SiC nw felt reaches −44.3 dB at 3.85 GHz with the corresponding EAB of 0.64 GHz (3.6–4.24 GHz) at a thickness of 3.5 mm. The density of the SiC nw felt is as low as 0.022 g/cm3 due to the high porosity (99.3%) of 3D networks, which fulfills lightweight requirements and highly efficient electromagnetic wave absorption. [ABSTRACT FROM AUTHOR]

The quality criteria for fairing used to protect antenna devices (AD) of radar stations (RS) from environmental influences are the requirements for ensuring and maintaining strength and protective properties with minimal insertion loss of the transmitted electromagnetic wave (EMW). It is important to assess the influence of manufacturing technology on these parameters, identifying narrow critical zones on the product with minimum strength characteristics and maximum EMW insertion loss. Calculation models of the stress state in a three-layer sandwich are presented with the identification of critical places from a given type of loading. A method for flaw detection of fairings is presented, taking into account the influence of the dynamics of changes in the maximum allowable threshold of EMW losses, which is extremely necessary for analyzing the technological process and correcting strength calculations. [ABSTRACT FROM AUTHOR]