Electromagnetic Propagation Research Articles

High-frequency demagnetization of magnetite suspensions

Purpose. The research purpose is to substantiate the high-frequency demagnetization technology parameters for magnetite suspensions, taking into account the established patterns of changes in the electrical resistivity of circulating water and changes in magnetic field induction depending on the concentration of dissolved salts. Methods. The circulating water from the processing plant is a part of the magnetite suspension. The change in the electrical conductivity indices of this water was studied under laboratory conditions using the conductometric method with alternating current of various frequencies. The degree of demagnetization of the magnetite particles was determined based on the study of the sedimentation kinetics of both magnetized and demagnetized magnetite suspensions. A special device was used to demagnetize the magnetite particles. It is a solenoid which, together with a capacitor, forms an oscillatory circuit in which damped high-frequency electromagnetic oscillations are periodically generated by current pulses supplied. Findings. The aspects of the high-frequency electromagnetic field propagation within the magnetite suspension have been revealed, taking into account the field energy dissipation factor and the influence of the suspension technological parameters (electrical resistivity of the circulating water, solid phase concentration) on the characteristics of the electromagnetic field. A relationship between the concentration of magnetite in the suspension and the electromagnetic field dissipation factor has been determined. As a result of determining the sedimentation kinetics, it has been found that the settling rate of the demagnetized magnetite suspension is lower compared to the magnetized one. Originality. The dependencies of the change in the electrical resistivity of the circulating water from the processing plant on the salt content, as well as the changes in the magnetic field induction along the solenoid axis on the distance from its edge and the surrounding medium, have been obtained. It has been found that to ensure complete demagnetization of magnetite, it should be demagnetized at least twice within the solenoid operating space. This provides a maximum suspension flow velocity of 5.6 m/s, while the sedimentation rate of the demagnetized suspension decreases by a factor of 3.1 compared to the magnetized one. This indicates the effectiveness of demagnetization and the destruction of interparticle magnetic interactions. Practical implications. The research can serve as a basis for determining rational parameters in the design of high-frequency demagnetizing devices. Their application makes it possible to improve the beneficiation indicators of magnetite ores, bringing them closer to theoretically possible levels, enhancing the efficiency of subsequent classification processes, and reducing the load on grinding equipment.

Fast 2D forward modeling of electromagnetic propagation well logs using finite element method and data-driven deep learning

Fast 2D forward modeling of electromagnetic propagation well logs using finite element method and data-driven deep learning

Effect of Titanium Mandible Implant on the Electric Field and SAR Distribution Caused by Mobile Phone Within the User’s Head

The primary objective of this investigation is to assess the influence of a mandible implant on the electric field distribution and the specific absorption rate (SAR) within the cell phone user’s head. The procedure is based on numerically solving the electromagnetic propagation equation. This is an effective technique for the assessment of electric field distribution and the energy levels absorbed by the organs inside the head. In order to accomplish this, realistic three-dimensional head, implant, and mobile phone models are developed. The frequency applied in the simulations is 2600 MHz. Electric field strength and SAR distributions within the head are presented and examined. A comparative analysis was performed on both models, with and without a titanium mandible implant, to assess the influence of the implant on neighboring biological tissues. The results indicate that both values rise inside biological tissues close to the mandible implant. Face-to-phone safe distances are identified when the values of the electric field and SAR are under the allowable levels set by regulations.

Development and Validation of an Electromagnetic Induction-Based Thermal Propagation Test Method for Large-Format Lithium-Ion Battery Systems

This study establishes a standardized framework for thermal propagation test in nickel-7 lithium-ion battery systems through a high-frequency electromagnetic induction heating method. The non-intrusive triggering mechanism enables precise thermal runaway initiation within two seconds through localized eddy current heating (>1200 °C), validated through cell-level tests with 100% success rate across diverse trigger positions. System-level thermal propagation tests were conducted on two identical battery boxes. The parallel experiments revealed distinct propagation patterns influenced by system sealing quality. In the inadequately sealed system (Box 01), flame formation led to accelerated thermal propagation through enhanced convective and radiative heat transfer. In contrast, the well-sealed system (Box 02) maintained an oxygen-deficient environment, resulting in a controlled sequential propagation pattern. The testing methodology incorporating dummy modules proved efficient for validating thermal protection strategies while optimizing costs. This study contributes to a deeper understanding of thermal runaway propagation mechanisms and the development of standardized testing protocols for large-format battery systems.

Digital Twins of Electromagnetic Propagation Environments for Live 5G Networks—Part I: Channel Acquisition, EM Simulation, and Verification

Digital Twins of Electromagnetic Propagation Environments for Live 5G Networks—Part I: Channel Acquisition, EM Simulation, and Verification

Digital Twins of Electromagnetic Propagation Environments for Live 5G Networks—Part II: High-Fidelity Emulation in the MPAC Setup

Digital Twins of Electromagnetic Propagation Environments for Live 5G Networks—Part II: High-Fidelity Emulation in the MPAC Setup

Thank You to Our 2024 Reviewers

Abstract The Editors thank the 2024 peer reviewers. As you are aware, the journal Radio Science (RDS) publishes original research papers on electromagnetic propagation and its applications. In 2024, we received a total of 206 manuscripts for consideration for publication in the RDS. We tried very carefully to find reviewers who were best fit to the topics of manuscripts. You worked hard in the peer‐review process and gave us excellent evaluations. Our journal would never have kept a high reputation without your continued efforts. Thank you all for your significant contributions to the review process and we look forward to working with you also this year and in the coming years.

Motion Cancellation Technique of Vital Signal Detectors Based on Continuous-Wave Radar Technology.

Continuous-wave (CW) radar sensors can remotely measure respiration and heartbeat by detecting the periodic movements of internal organs. However, external disturbances, such as random body motion (RBM) or environmental interference, significantly degrade the signal-to-noise ratio (SNR) and reduce the accuracy of vital sign detection. The various motion cancellation techniques that have been proposed to enhance robustness against RBMs include improvements in radar architecture, advanced signal processing algorithms, and studies on electromagnetic propagation characteristics. This paper provides a comprehensive review of recent advancements in motion cancellation techniques for CW radar-based vital sign detectors and discusses future research directions to improve detection performance in dynamic environments.

Interference and precursor signal analysis based on random forest and improved logistic regression model

Coal is the main energy and industrial raw material in China. In order to prevent the risks of coal mining and ensure the safety and efficiency of coal mining, this paper established random forest model, ADF and MK test model and logistic regression model, and used autocorrelation function algorithm, Fourier transform and sliding window transformation of time series data to analyze and optimize the characteristics of interference signals and precursor characteristics. For the first work, the huge data is preprocessed, tested, and outliers are removed, and the time characteristics are taken to aggregate and classify the data. For work (1.1), data parameters were sorted out, Fourier transform prediction signal model was initially established, and characteristic values were extracted by wavelet transform. Finally, autocorrelation function algorithm was used to optimize and analyze the results. The final results were shown in Table 4 for the data characteristics of electromagnetic radiation (EMR) interference signals and Table 5 for the interference signals of acoustic propagation signals. For work (1.2), a random forest model is established, with sliding window transformation of time series data, window size is specified, boundary processing mode is specified, and label value is defined as interference and normal. The data set is divided into training set and test set in the way of eighty-two allocation. After AE training, there are three stages of training. Finally, random forest algorithm is used to calculate the electromagnetic radiation interference signal interval. For work (2.1), the model and algorithm of work 1 are used to identify the trend characteristics of the data before the occurrence of electromagnetic radiation and acoustic emission signals, and the signal data are judged to have a "slightly rising" trend. The statistical values are compared by KS trend test, and the trend characteristics of normal and precursor signals are calculated by using the autocorrelation function algorithm. A trend feature table is obtained for the precursory feature data of electromagnetic radiation and acoustic propagation signal. For work (2.2), Augmented dickey-Fuller and MK test models of the system were established. For work 3, a logistic regression model is established to predict the probability of precursor feature data appearing at the last moment of multiple time periods. By using maximum likelihood estimation to train model parameters, the characteristics of the last data collection moment of each time period are predicted, and the probability of precursor feature appearing at each moment is output. As shown in Table 14, the probability of precursor features appearing at the time when the data of multi-classification logistic regression is located is obtained. **************** ACKNOWLEDGEMENTS**************** This work is supported by ministry of education industry-university cooperative education project (Grant No.: 231106441092432), the research and practice of integrating "curriculum thought and politics" into the whole process of graduation design of Mechanical engineering major: (Grant. No.: 30120300100-23-yb-jgkt03), research on the integration mechanism of "course-training-competition-creation-production" for innovation and entrepreneurship of mechanical engineering majors in applied local universities (Grant. No.: CXKT202405), Mechanical manufacturing equipment design school-level "gold class" construction project (Grant. No.: 30120324001).

An open source code for modeling radio wave propagation in earth’s ionosphere

We present FARR (Finite-difference time-domain ARRay), an open source, high-performance, finite-difference time-domain (FDTD) code. FARR is specifically designed for modeling radio wave propagation in collisional, magnetized plasmas like those found in the Earth’s ionosphere. The FDTD method directly solves Maxwell’s equations and captures all features of electromagnetic propagation, including the effects of polarization and finite-bandwidth wave packets. By solving for all vector field quantities, the code can work in regimes where geometric optics is not applicable. FARR is able to model the complex interaction of electromagnetic waves with multi-scale ionospheric irregularities, capturing the effects of scintillation caused by both refractive and diffractive processes. In this paper, we provide a thorough description of the design and features of FARR. We also highlight specific use cases for future work, including coupling to external models for ionospheric densities, quantifying HF/VHF scintillation, and simulating radar backscatter. The code is validated by comparing the simulated wave amplitudes in a slowly changing, magnetized plasma to the predicted amplitudes using the WKB approximation. This test shows good agreement between FARR and the cold plasma dispersion relations for O, X, R, and L modes, while also highlighting key differences from working in the time-domain. Finally, we conclude by comparing the propagation path of an HF pulse reflecting from the bottomside ionosphere. This path compares well to ray tracing simulations, and demonstrates the code’s ability to address realistic ionospheric propagation problems.

Closed-form analytical solution for the transfer matrix based on Pendry-MacKinnon discrete Maxwell’s equations

The transfer matrix method effectively analyzes wave scattering in homogeneous layered media but struggles with structures having spatially varying material properties. This paper introduces an analytic method to determine transfer matrix elements for all Bloch-Floquet modes in structures with spatially varying dielectric properties. We demonstrate the approach using a bilayer device of two thin layers, each patterned with tessellated polygons representing distinct dielectric regions. Our analytical formulas are derived from Pendry and MacKinnon’s discrete version of Maxwell’s equations. The result reduces the complex interaction of many path operators into key channels guiding electromagnetic field propagation from input to output.

Breaking Barriers in-Vivo THz Communication Analysis for Nano Networks in Human Tissues

Body Nano-Communication based on RF radio communication in the terahertz band supports health and fitness industry applications. Nano communications primary facilitate real-time monitoring of biological and chemical substances inside the human body, helping an early detection of stroke and heart attack risks. Monitoring small communication range inside the human body via electromagnetic propagation is not an easy task; thus, in this paper, we investigate the path loss of radio propagation in three human tissues: blood, skin, and fat using a Tera-Hertz frequency range in between 0.5 and 1.5 THz. The results support the idea that the path loss inside the human body depends on the dielectric loss of human tissues and the function of frequency and distance. It also shows that increasing the distance and the frequency of the signal inside the tissues, such as blood, fat, and skin, the path loss increases because the attenuation increases when the frequency increases. Furthermore, the study examines the effect of Doppler as a method of measuring the speed of blood flow to predict the early risks being considered.

A program for modeling the RF wave propagation of ICRF antennas utilizing the finite element method

Abstract Controlled nuclear fusion represents a significant solution for future clean energy, with ion cyclotron range of frequency (ICRF) heating emerging as one of the most promising technologies for heating the fusion plasma. This study primarily presents a self-developed 2D ion cyclotron resonance antenna electromagnetic field solver (ICRAEMS) code implemented on the MATLAB platform, which solves the electric field wave equation by using the finite element method, establishing perfectly matched layer (PML) boundary conditions, and post-processing the electromagnetic field data. This code can be utilized to facilitate the design and optimization processes of antennas for ICRF heating technology. Furthermore, this study examines the electric field distribution and power spectrum associated with various antenna phases to investigate how different antenna configurations affect the electromagnetic field propagation and coupling characteristics.

Wideband Circularly Polarized Conformal Dielectric Resonator Antenna for High Gain Applications

ABSTRACTA compact and circularly polarized convex dielectric resonator antenna (CDRA) is investigated in this communication. Eigenmode method is used to analyze electromagnetic field propagation and resonant frequency of the antenna. Benefits of conformal structure over a planar surface are mentioned. A pair of vertical slots are introduced on the ground plane to produce orthogonal degenerate modes. Finally, the proposed curved DRA provides a fractional impedance bandwidth of 22%, axial ratio bandwidth of 11.27% and a stable gain of more than 5 dBi over the desired passband with a peak gain of 7 dBi. To validate the simulated results, a prototype is fabricated and measured.

Особенности формирования синтетических изображений радиометрических величин в ИК области спектра

Physically correct synthetic images of 3D scenes in a given wavelength range are of great importance in solving some applied problems. Such data generation is based on a physical interactions modelling, including electromagnetic radiation propagation in a scene space. This paper presents the results of a ray tracing mechanism development in a 3D scene modeling software package. An algorithm for calculation radiative heat transfer that allows accounting a radiation from multiple bodies in the scene is proposed. In order to be executed on graphical processors it is implemented in form of shader programs. Each emitted ray, which simulates the propagation of an electromagnetic wave, undergoes no more than two interactions with bodies and makes an addition to an observed area radiation in a number of photons given wavelengths range and solid angle. To evaluate the algorithm a number of model scenes were proposed, on which comparative study was carried out in case of infrared region modeling. As results show, taking into account the mechanisms of radiative heat transfer allow for qualitative improvement of the resulting images and makes a significant contribution to the background signal.

On-chip reconfigurable diffractive optical neural network based on Sb2S3.

A Sb2S3-based reconfigurable diffractive optical neural network (RDONN) for on-chip integration is proposed. The RDONN can be integrated into standard silicon-on-insulator systems, offering a compact, passive, all-optical solution for implementing machine learning functions. The weights of the proposed optical chip are reconfigurable without the need to modify hardware structures or re-fabricate the chip. Its main structure consists of multilayer metalines made from Sb2S3, a low-loss phase change material. The RDONN architecture is constructed using the two-dimensional electromagnetic propagation model and implements the classification task on the Iris dataset with both intensity modulation and phase modulation inputs. This demonstrates its feasibility, with classification accuracies reaching 95.0% and 98.3%, respectively. Our model enables reconfigurable manipulation of the weights in the on-chip diffractive optical neural network, which can be used in the design and fabrication of real chips. This advancement holds significant promise for future all-optical in situ learning systems.

NUMERICAL SIMULATION IN CALCULATIONS OF TECHNOLOGICAL SYSTEMS OF ELECTROMAGNETIC PROCESSING. PART I: PROPAGATION OF THE ELECTROMAGNETIC FIELD

The article deals with the problem of numerical modeling when calculating electromagnetic field propagation in electromagnetic molding systems. From the analysis of open information sources, it follows that the problem of numerical modeling when creating new technological operations of electromagnetic molding or when improving existing ones is relevant in a scientific and practical sense. This is due to the need to perform adequate numerical modeling and computational analysis of technological systems and technological operations at the stage of creation and improvement. With regard to technological systems of electromagnetic processing, calculation schemes and models should make it possible to study the propagation of a non-stationary electromagnetic field and to study the processes of nonlinear deformation of technological elements, which is caused by the force interaction of the induced electromagnetic field with the field of the source. Adequate numerical modeling must be based on appropriate calculation procedures based on numerical methods. The article substantiates the need to use numerical methods for calculation analysis, which allow creating calculation schemes closer to reality to a greater extent compared to the case of using analytical approaches and methods. The most effective numerical method is the finite element method, which allows the analysis of the non-stationary electromagnetic field and deformation within the same calculation scheme. In this case, within the framework of the finite element method, iterative schemes can be created that allow taking into account nonlinear effects. Here, nonlinear effects can be caused by the dependence of the mechanical and electrophysical properties of the material on temperature, the plastic nature of the deformation, as well as the need to account for contact phenomena. The results of modeling the propagation of the electromagnetic field of a single-turn inductor are presented.

Electromagnetic Absorption Mechanism of TPMS‐Based Metastructures: Synergy Between Materials and Structures

Abstract3D metastructure absorbers have gained attention for their lightweight, load‐bearing capabilities, and superior electromagnetic wave absorption. However, the complex interplay between unit cell geometry, material properties, and electromagnetic response is not well understood, hindering the design of high‐performance devices. A multi‐scale model, validated is presented by simulations and experiments, that clarify the relationship between materials, structures, and electromagnetic behavior in 3D metastructures. By systematically investigating strut‐based and sheet‐based structures, volume fraction, unit size, crystal lattice orientation, and density gradient within TPMS‐based unit cells, it is revealed that unit geometry significantly influences electromagnetic field propagation and reflection loss. Specifically, under the same unit size, sheet‐based TPMS metastructures exhibit stronger reflectivity than strut‐based ones, while multilayer structures show the opposite trend. The direct correlation is also further confirmed between geometric symmetry and polarization insensitivity, with orthogonal isotropic superstructures displaying excellent polarization‐insensitive properties. This finding provides a new design principle for achieving robust, angle‐independent absorption in these materials. This work enhances understanding of the structure‐electromagnetic behavior interplay, guiding the design of next‐generation broadband, wide‐angle, and polarization‐insensitive devices.

The inverse problem of identifying complex hyperbolic equation source terms in electromagnetic propagation

Abstract This article investigates the inverse problem of determining the source term of the hyperbolic equation for electromagnetic propagation using terminal data. This study is an important method for identifying propagation sources in electromagnetics. Unlike wave equations, the complexity of the underlying equations can make theoretical analysis quite difficult. Firstly, the uniqueness of the inverse problem was proved using the energy method. Then, based on the optimal control framework, the inverse problem was transformed into an optimal control problem, and the existence of the optimal solution and its necessary conditions were established. Secondly, the global uniqueness and stability of the optimal solution have been proven, which is a completely new conclusion. This has laid a solid theoretical foundation for numerical algorithms. Finally, it is proposed to apply the Landweber iteration method and conjugate gradient method to this problem, and some numerical examples are provided to demonstrate the effectiveness and convergence speed of these two algorithms.

Electromagnetic Propagation Characteristics of Submarine Cable Detection With Finite Element Analysis

Electromagnetic Propagation Characteristics of Submarine Cable Detection With Finite Element Analysis