Electromagnetic Radiation Problems Research Articles

Interlayer growth of magnetic nanocomponent in Ti3C2Tx MXene EMW absorbers for periodic electromagnetic synergetic network

Transition metal carbides/carbonitrides (MXene) exhibit huge potential as electromagnetic wave (EMW) absorbers in dealing with electromagnetic radiation problem that rise due to the rapid development of 5G era. The incorporation of magnetic materials can effectively mitigate the impedance mismatch and singular loss mechanisms inherent in pure MXenes (PMs). However, challenges persist due to issues such as random distribution, complex preparation processes, and inadequate interaction. In this study, Ti3C2Tx/Ni hybrids were synthesized using a one-pot method, wherein Ni, derived from molten salt, replaces Al layer of MXene, facilitating the in-situ growth of Ni nanocomponents within the interlayered region. The periodic electromagnetic synergetic network of “MXene-Ni-MXene-Ni-MXene” provides substantial magnetic resonance, eddy current loss, interface polarization, defect polarization, and dipole polarization, enriching the loss mechanism. By regulating the concentration of Ni, the intrinsic poor impedance matching of MXene was improved. Consequently, Ti3C2Tx/Ni hybrid exhibited exceptional electromagnetic wave absorption (EMA) performance, achieving a reflection loss (RL) of −64.51 dB and an effective absorption bandwidth (EAB) of 4.96 GHz at a matching thickness of 1.98 mm. Additionally, the super radar cross-section (RCS value = −15.73 dB m2) endow it potential in practical application. This work provides a facile method for achieving unique electromagnetic synergetic loss mechanism, thus paving the way for exploring high-efficient MXene-based EMW absorbers.

A review of recent advances in MXenes/polymer‐based electromagnetic interference shielding materials

AbstractThe booming development of mobile devices has remarkably improved the lives of people, but it also leads to severe electromagnetic radiation problems. Therefore, it has become significantly important to develop electromagnetic interference (EMI) shielding materials for electromagnetic protection. In recent years, MXenes have attracted much attention in the field of EMI shielding, owing to outstanding electrical conductivity, high specific surface area and hydrophilicity. Firstly, this review introduces EMI shielding mechanism and categorization of EMI shielding materials. Subsequently, the research progress of MXenes/polymer‐based EMI shielding materials is reviewed in detail, especially for preparation methods of MXenes/polymer‐based EMI shielding blocks. Finally, the key scientific problems in MXenes/polymer‐based EMI shielding materials are proposed, and their development trend are prospected.Highlights The EMI shielding mechanism and categorization of EMI shielding materials is presented. The latest research progress of MXenes/polymer‐based EMI shielding materials is reviewed. Scientific problems for MXenes/polymer‐based EMI shielding materials are proposed. Development trend of MXenes/polymer‐based EMI shielding materials is prospected.

Tailorable effective microwave absorption bandwidth of chitosan-derived carbon-based aerogel under different compression

Confronted with ever-increasing electromagnetic radiation problems, developing microwave absorbing materials with tunable effective absorption bandwidth (EAB) is in high demand. In this work, chitosan-derived carbon-based aerogel was synthesized by unidirectional freeze-drying and the following high-temperature carbonization process. The dielectric-magnetic coupling effect was facilitated by the construction of the 3D conductive network, along with the decoration of the Co nanoparticles and the doping of heteroatoms within the carbon-based framework. Therefore, the aerogel achieved minimum reflection loss intensity of -44.30 dB at 5.20 GHz when carbonizing the precursor at 800 °C. More significantly, the strain-responsive properties of the aerogel endows it with tailorable electromagnetic response behaviors, thereby controlling the effective absorption bandwidth covering from X band to Ku band. This work paves the way for designing next-generation microwave absorption materials with tunable microwave absorption bandwidth, catering to stringent practical requirements prospectively.

Extension of the method of images in electromagnetism at an interface between two lossless dielectric media

The method of images is well-known in electrostatics and electromagnetic radiation problems, like currents on a metallic ground plane to replace the original problem. This paper extends the method of images to the case of a dipole antenna on a dielectric ground plane, like concrete, considering that from 1 GHz to 40 GHz is a low-loss dielectric material. The contribution of this work is the model that expresses the electric and magnetic fields through the method of imaging for a dipole on a dielectric ground plane, for vertical and horizontal polarization. These results can be applied to propagation models to the mobile communications like 5G and 6G technologies. The wave impedance of the electromagnetic wave obtained has been discussed. This work allows replacing the treatment of Sommerferld's of a dipole antenna on a dielectric ground with losses with the extension of the image method.

A Novel Parallel Direct Solver Using Adaptive Cross Approximation for Analysis of Electromagnetic Radiation Problems With Complex Structures

A Novel Parallel Direct Solver Using Adaptive Cross Approximation for Analysis of Electromagnetic Radiation Problems With Complex Structures

An Efficient Goal-Oriented Adaptive Finite Element Method for Accurate Simulation of Complex Electromagnetic Radiation Problems

A goal-oriented adaptive frequency domain finite element method for solving electromagnetic radiation problems including complex structures is presented in this paper. Compared with the traditional adaptive finite element method, the goal-oriented method can flexibly control the refined regions according to the parameters of interest; therefore it has better convergence and has made significant progress in scattering problems and eigenvalue problems. To simulate complex antennas, this paper proposes an error indicator with high accuracy and low computational cost, and it uses the adjoint problem to weight element residuals without additional degrees of freedom. Moreover, high-quality mesh refinement algorithms adapted to this indicator are developed using a suitable point insertion strategy for multiscale structures. By simulating two practical antennas, comparisons with the traditional goal-oriented FEM and the well-developed <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">h</i> -adaptive finite element method in commercial software demonstrate the accuracy and efficiency of the proposed method.

Design and Performance Analysis of New Coupling Magnetic Core Structure for Dynamic Wireless Charging System of Electric Vehicle

Aiming at the problems of high cost, low efficiency, low power, and high electromagnetic radiation in the dynamic wireless charging system for electric vehicles (EVs), the cover‐like coupling structure and the return‐like coupling structure are designed, and the unique concave structure has excellent engineering practicability. Using Ansoft software for simulation and analysis, the newly proposed two coupling structures have significantly improved the induced voltage and electromagnetic induction strength at the pickup end compared with other commonly used coupling core structures. According to the advantages of practical applications, the application of its composite core structure for simulation and analysis proves that the cover‐like structure of the magnetic field strength at the pickup end not only enhances the magnetic field strength on the coil but also has a good magnetic field shielding effect. The lateral displacement of the EV is kept within the range of 10 cm, the coupling distance is 0–5 cm, the charging is stable, and the transmission efficiency is high. Finally, a dynamic wireless charging experimental platform for small EVs is constructed, which verifies that the new coupling core structure can significantly improve the transmission power and efficiency of the charging system and significantly reduce the economic cost.

Electromagnetic radiation from electrically driven vehicles

The problem of electromagnetic radiation of vehicles exists and worries people, because it is not clear what is the safe level of frequency, intensity, time spent by drivers and passengers in vehicles, etc. The article is devoted to the disclosure of the problems of adverse effects of electromagnetic fields (EMF) and electromagnetic radiation (EMR) of modern hybrid and electric vehicles on drivers, passengers, pedestrians and the environment. The purpose of the study was to investigate the process of occurrence, propagation and impact of negative functions of electromagnetic radiation on biological objects, their propagation speed, flicker, wavelength and frequency, and radiation devices in electric and hybrid vehicles. The methodology of the article is based on the results of research by scientists from around the world and our own research and experiments, the results of which are presented in this article. The results of the scientific work are reviewed from researchers on this topic and their own tests are described The authors point out the need to measure electromagnetic radiation at the stages of their operation, repair and manufacture, since these vehicles running on electric traction generate magnetic fields that can violate electromagnetic safety. This is because electric vehicles have power plants, sensors, control, information and communication systems. Electric currents flowing through electric motors, power circuits, and batteries while driving generate magnetic fields (MFs) in the low frequency ranges (ultra low frequency (ULF), 0.001 - 10 Hz; extremely low frequency (ELF), 10 - 300 Hz).Higher harmonics of the electric field in electric vehicles and hybrid vehicles are generated by various electronic devices on board, information and communication systems. For example, in hybrid vehicles, magnetic pulses of up to 5 kHz are generated when the internal combustion engine is switched to electric mode. In addition, all types of cars generate a low-frequency pulsating magnetic field when the steel wheel disks rotate. The frequency f of this field is determined by the wheel speed and is usually f 20 Hz, but the spectrum also contains harmonics. The scientific novelty is that for the first time the concept of modeling and optimization of electromagnetic hazard assessment of electric vehicles and hybrid vehicles is presented, which has a unified approach to the study of the magnetic field regardless of the structure and design schemes of their power plants at the stage of operation; for the first time methods for assessing important parameters of the magnetic field of electric vehicles and hybrid vehicles at the stage of operation are developed based on the concept of optimal control of the power plant depending on the operating conditions. The practical significance is the originality, which lies in the fact that the authors have considered the problems of determining the moment of occurrence of traffic hazards in various road and transport situations and the technical hazards of various types of electric vehicles and hybrid vehicles.

Research progress and practical application of magnetic composite absorbing materials

The update and iteration of communication technology, the continuous emergence of new electronic devices, smart home appliances and new energy vehicles, and the widespread use of military electromagnetic technology have caused serious electromagnetic radiation problems. Nanomagnetic materials have special electromagnetic properties and become the continuous research object of absorbing materials, especially in the development of low-frequency absorbing materials. This paper reviews the theoretical basis and research status of nanomagnetic materials in low-frequency absorbing materials and composite absorbing materials that are "thin, light, wide, and strong". In addition, the basic research is aimed at realizing the final application, and this paper also summarizes the application status of the absorbing agent in practical application.

Explicit Definitions for the Electromagnetic Energies in Electromagnetic Radiation and Mutual Coupling

It is still difficult to accurately evaluate the reactive electromagnetic energy and the radiative electromagnetic energy of a radiator, because there are no explicit expressions for them. This paper proposes to borrow the energy concept in the charged particle theory and separate the total electromagnetic energy of a radiator into three parts: a Coulomb–velocity energy, a radiative energy and a macroscopic Schott energy. Consequently, the Poynting vector is considered to include a real radiative power flow by the radiative energy and a pseudo power flow caused by the fluctuation of the reactive energy. The energies involved in the electromagnetic mutual coupling are separated in a similar way. All energies are defined with explicit expressions in which the vector potential plays an important role. The time domain formulation and the frequency domain formulation of the theory are consistent with each other. The theory is verified with the Hertzian dipole. Numerical examples demonstrate that this theory may provide proper interpretations for electromagnetic radiation and mutual coupling problems.

General method for solving electromagnetic radiation problems in an arbitrary linear medium

General method for solving electromagnetic radiation problems in an arbitrary linear medium

Aramid nanofiber based Ag/Fe3O4-CNT/rGO hybrid membrane for high-performance electromagnetic interference shielding

With the increase of modern integrated electronic and telecommunication systems, high-performance electromagnetic interference (EMI) shielding materials with flexibility, outstanding thermal conductive properties and superior EMI shielding performances are designed to solve the problems of electromagnetic radiation and heat accumulation. Herein, flexible asymmetric trilaminar architecture film with good mechanical properties is prepared via the facile three-step vacuum-assisted filtration (VAF) followed by hot-pressing approach, which is composed of silver-plated aramid nanofibers (ANF-Ag), ANF-Fe3O4&CNT (ANF-FC) and ANF-reduced graphene oxide (ANF-rGO) layers. The conductive ANF-Ag and ANF-rGO layers acted as the EMI shielding, thermal conductive layers, and supporting substrate layers. The magnetic ANF-FC layer played the important role in synergistically enhancing the EMI shielding performance. The resultant flexible and asymmetric trilaminar hybrid membrane with a thickness of 112 µm exhibited maximum thermal conductivity of 8.5 W m−1 K−1 and EMI SE of 67.5 dB, but also maintained a high tensile strength of 75.5 MPa and superb electrical conductivity of 2.46 × 106 S/m. This asymmetric trilaminar structures film holds great promise to addresses issues of electromagnetic radiation and heat accumulation for personal smart electronic devices, wearable electronics, electronic telecommunication systems.

Advances in Graphene-Polymer Nanocomposite Foams for Electromagnetic Interference Shielding.

With the continuous advancement of wireless communication technology, the use of electromagnetic radiation has led to issues such as electromagnetic interference and pollution. To address the problem of electromagnetic radiation, there is a growing need for high-performance electromagnetic shielding materials. Graphene, a unique carbon nanomaterial with a two-dimensional structure and exceptional electrical and mechanical properties, offers advantages such as flexibility, light weight, good chemical stability, and high electromagnetic shielding efficiency. Consequently, it has emerged as an ideal filler in electromagnetic shielding composites, garnering significant attention. In order to meet the requirements of high efficiency and low weight for electromagnetic shielding materials, researchers have explored the use of graphene-polymer nanocomposite foams with a cellular structure. This mini-review provides an overview of the common methods used to prepare graphene-polymer nanocomposite foams and highlights the electromagnetic shielding effectiveness of some representative nanocomposite foams. Additionally, the future prospects for the development of graphene-polymer nanocomposite foams as electromagnetic shielding materials are discussed.

Characteristic Mode Analysis: Application to Electromagnetic Radiation, Scattering, and Coupling Problems

Characteristic Mode Analysis: Application to Electromagnetic Radiation, Scattering, and Coupling Problems

Fe3O4 and Ag micro/nano coating for high-efficiency flame retardancy and electromagnetic interference shielding

In order to solve the growing problem of electromagnetic radiation and accidental fires due to heat accumulation or electric heating smart clothing, electromagnetic shielding materials with fire resistance are urgently needed. Herein, a polydopamine-assisted polysulfonamide (PSA) nonwoven fabric was designed as a hydrophilic substrate and nano‑silver was employed as a conductive layer. A mixed solution of Fe3O4 with ammonium polyphosphate (APP) was further treated to obtain the surface of microspheres with incombustibility. Interestingly, the micro-nano electromagnetic wave loss gradient enabled the PSA/Ag/Fe3O4/APP-1(PSA/AFA-1) fabric to exhibit efficient absorption-dominant electromagnetic shielding performance, and the optimized fabric exhibited an EMI SE value of 45.5 dB at X-band (8.2–12.4 GHz) with a shielding efficiency of 99.99 %, which remained stable under multiple twisting and bending. This study opens up a new idea for the preparation of fireproof EMI shielding materials with broad application prospects as well as next-generation multi-purpose garments.

A Data-Science Approach for Creation of a Comprehensive Model to Assess the Impact of Mobile Technologies on Humans

Mobile technologies are an essential part of people’s everyday lives since they are utilized for a variety of purposes, such as communication, entertainment, commerce, and education. However, when these gadgets are misused, the human body is exposed to continuous radiation from the electromagnetic field created by them. The communication services available are improving as mobile technologies advance; however, the problem is becoming more severe as the frequency range of mobile devices expands. To solve this complex case, it is necessary to propose a comprehensive approach that combines and processes data obtained from different types of research and sources of information, such as thermal imaging, electroencephalograms, computer models, and surveys. In the present article, a complex model for the processing and analysis of heterogeneous data is proposed based on mathematical and statistical methods in order to study the problem of electromagnetic radiation from mobile devices in-depth. Data science selection/preprocessing is one of the most important aspects of data and knowledge processing aiming at successful and effective analysis and data fusion from many sources. Special types of logic-based binding and pointing constraints are considered for data/knowledge selection applications. The proposed logic-based statistical modeling method provides both algorithmic as well as data-driven realizations that can be evolutionary. As a result, non-anticipated and collateral data/features can be processed if their role in the selected/constrained area is significant. In this research, the data-driven part does not use artificial neural networks; however, this combination was successfully applied in the past. It is an independent subsystem maintaining control of both the statistical and machine-learning parts. The proposed modeling applies to a wide range of reasoning/smart systems.

Hierarchical dandelion-like CoS2 hollow microspheres: self-assembly and controllable microwave absorption performance.

The emerging electromagnetic radiation and interference problems have promoted the rapid development of microwave absorption materials (MAMs). However, it remains a severe challenge to construct high-performance microwave absorption materials with broadband, lightweight and corrosion resistance within low filling contents. Herein, hierarchical dandelion-like CoS2 hollow microspheres were reasonably constructed via a solvothermal-hydrothermal etching-in situ vulcanization process. The structure morphology, composition and electromagnetic performance of all samples have been thoroughly tested. The research results demonstrated that the structure morphology of the prepared samples with a volume ratio of 1 : 1 between ethanol and H2O remained intact without serious damage. Notably, the as-obtained hierarchical dandelion-like CoS2 hollow microspheres (25 wt%) exhibited excellent microwave absorption capacity with a minimum reflection loss (RLmin) of -47.3 dB and the corresponding effective absorption bandwidth (EAB) of 8.4 GHz at 3.3 mm. Moreover, the broadest effective absorption bandwidth (EAB, RL < -10 dB) reached 9.0 GHz (9.0-18.0 GHz) at the matching thickness of 3.2 mm. The unparalleled multiple features including hierarchical hollow structure, tunable complex permittivity as well as the enhanced impedance matching endowed CoS2 great promise as high-performance microwave absorbers for solving the problem of electromagnetic pollution.

Simulation and experimental research on electromagnetic radiation from suspended permanent magnetic levitation train

With the continuous development and innovation in the field of global magnetic levitation technology, the suspended permanent magnet maglev rail transit system has emerged. At present, no mature relevant technical standard references are available in the world. To study the electromagnetic radiation problem of the permanent magnet maglev train system, we use the finite element method to simulate and analyze the Halbach array track of different combinations of suspension modules, and the six-channel high-precision magnetic field test system is used to test and compare the actual engineering magnetic fields. The results show that the permanent magnet magnetic suspension rail transit system can shield the magnetic energy of the suspension module in the rail beam to reduce the influence of electromagnetic radiation. With the increase in suspension height between the rail and vehicle magnets, the generated magnetic field intensity exhibits a significantly weakening trend. The magnetic field energy of the permanent magnet maglev train is maintained at the centimeter level. Combined with the actual project, the passengers on the train and pedestrians, and residents along the red rail are not affected by the magnetic field intensity of the permanent magnet. This paper provides a theoretical basis for resolving people’s concerns about the electromagnetic radiation of maglev trains, and provides important theoretical support for the development of maglev rail transit.

Directive properties of radiating source systems in massive electromagnetism

We investigate the problem of electromagnetic radiation in massive electromagnetism with focus on the directive radiation characteristics of Proca antennas (sources embedded into Proca metamaterial domains.) It is theoretically demonstrated that the recently proposed nonlocal Proca metamaterial implies the existence of point nonlocal sources possessing a perfectly isotropic radiation pattern. Based on rigorous analysis, we derive exact expressions for the directive radiation patterns of arbitrary discrete distributions of Proca source systems, i.e., radiating arrays emitting massive photons. Examples of linear discrete Proca arrays are given and comparison with massless photon radiation sources is provided.

Using the Interpolative Decomposition to Accelerate the Evaluation of Radome Boresight Error and Transmissivity

Based on the method of moments, the interpolative decomposition (ID) technique is extended to accelerate the evaluation of radome boresight error (BSE) and transmissivity, which belongs to electromagnetic radiation problems with the right-hand side (RHS) matrix containing multiple vectors. Because the RHS matrix from radiation problems has many null rows, the matrix can be first reduced to a compressed form, then decomposed by the ID technique to figure out the skeleton RHS vectors by exploiting its rank-deficient property. Iterative solutions are only executed for these skeleton vectors, followed by the restoration process to obtain the full solutions. Compared with the existing ID methods designed for scattering problems, the proposed ID method is much easier to implement and companied with a high solution efficiency. Numerical experiments are performed on an antenna array enclosed by a radome to evaluate the BSE and transmissivity, illustrating the performance and accuracy of the proposed method.