Electromagnetic Waves Research Articles

Вплив червоного та синього електромагнітного випромінювання на каталазну активність зародків в’юна Misgurnus fossilis L.

Photobiomodulation therapy is widely used to treat various pathological conditions. This therapy is based on the use of monochromatic light radiation. The light of the visible spectrum induces different biological effects at the molecular and cellular levels, both therapeutic and toxic. The obtained effect depends on the length of radiation, exposure, etc. One of the possible mechanisms of such influence is the regulation of pro-oxidant-antioxidant homeostasis. In order to clarify the mechanism of action of electromagnetic radiation (EMR) of different spectral composition, catalase (CAT) activity was investigated in germ cells of loach Misgurnus fossilis L. during embryogenesis. Since, loach embryos are an adequate system that reflects the physiological state of the cell both under normal conditions and as a result of the influence of various pharmacological, physical and chemical agents. The resulting zygotes were irradiated (10 min) with blue and red LEDs (λ = 460 and 660 nm, respectively). The activity of CAT was determined by the ability of hydrogen peroxi­de to form a stable colored complex with molybdenum salts. It was established that EMR of the red spectrum has the most pronounced biological effects and caused significant changes in catalase activity during embryogenesis relative to control and blue light. The maximum increase of the indicator occurs at the stage of 16 blastomeres, and at the stage of 8 and 10 divisions, a gradual decrease in enzymatic activity is observed. Irradiation by the light of the blue spectrum lasting 10 min did not cause significant changes in catalase activi­ty relative to the control at the early stages of loach embryogenesis. The obtained results suggest that CAT, one of the key enzymes of the antioxidant defense system, undergoes photoactivation under the influence of red light.

Electromagnetic scattering by curved surfaces and calculation of radiation force: Lattice Boltzmann simulations

This study aims to investigate the effectiveness of the lattice Boltzmann method (LBM) in studying the scattering of electromagnetic waves by curved and complex surfaces. The computation of Maxwell’s equations is done by solving for a pair of distribution functions, which evolve based on a two-step process of collision and streaming. LBM bypasses the need for expansion via vector spherical harmonics and thus is amenable to scatterers with complex geometries. We have employed LBM to compute the scattering width and radiation force for perfect electrically conducting and dielectric cylinders of circular and elliptical cross sections. Both smooth and corrugated surfaces are studied, and the results are compared against known analytical and numerical solutions from other methods. To ensure the broad applicability of the method, we have explored a wide range of parameter space—the dielectric constant and particle size to the wavelength ratio spanning Rayleigh, Mie, and geometrical optics regimes. Our simulations have successfully reproduced well-known analytical and numerical solutions, confirming the accuracy and reliability of the LBM for scattering calculations by complex-shaped objects.

Electromagnetic side-channel attack risk assessment on a practical quantum-key-distribution receiver based on multi-class classification

AbstractWhile quantum key distribution (QKD) is a theoretically secure way of growing quantum-safe encryption keys, many practical implementations are challenged due to various open attack vectors, resulting in many variations of QKD protocols. Side channels are one such vector that allows a passive or active eavesdropper to obtain QKD information leaked through practical devices. This paper assesses the feasibility and implications of extracting the raw secret key from far-field radiated emissions from the single-photon avalanche diodes used in a BB84 QKD quad-detector receiver. Enhancement of the attack was also demonstrated through the use of deep-learning model to distinguish radiated emissions due to the four polarized encoding states. To evaluate the severity of such side-channel attack, multi-class classification based on raw-data and pre-processed data is implemented and assessed. Results show that classifiers based on both raw-data and pre-processed features can discern variations of the electromagnetic emissions caused by specific orientations of the detectors within the receiver with an accuracy higher than 90%. This research proposes machine learning models as a technique to assess EM information leakage risk of QKD and highlights the feasibility of side-channel attacks in the far-field region, further emphasizing the need to utilise mechanisms to avoid electromagnetic radiation information leaks and measurement-device-independent QKD protocols.

Reverse design of load-bearing broadband metamaterial absorber assisted by deep learning

Abstract In response to the current challenges of narrow absorption bandwidth, weak load-bearing capacity, and low design efficiency in absorbing structures, this study focuses on the reverse design of load-bearing broadband metamaterial absorber. A parameterized model of load-bearing metamaterial absorber was developed by integrating the composite sandwich structure with the electromagnetic resonant layers. The resonant layer was constructed using the combination of Vicsek-fractal and circular rings, with resistive films employed to broaden the absorption bandwidth. A deep learning-based forward prediction model was established to accurately predict the absorbance of the metamaterial absorber. The SHapley Additive exPlanations (SHAP) framework was utilized to analyze the forward prediction network, revealing the influence of various design parameters on the absorbance at center frequencies across the L to K band spectrum. Additionally, the Group Teaching Optimization Algorithm (GTOA) was introduced into the design process, leading to the development of an automated reverse design method for metamaterial absorber that can achieve specific design objectives. Using the GTOA-based reverse design method, a metamaterial absorber capable of effectively absorbing vertically incident electromagnetic waves within the 3-20 GHz frequency range was designed. The designed absorbing structure was fabricated, and its absorption performance was measured using the arch method. The measurement results were found to be in good agreement with the simulation data. The absorbing mechanism of the designed metamaterial absorber was analyzed based on the calculation of equivalent electromagnetic parameters and the electromagnetic resonance observed at the resonant frequency. It was determined that the primary absorbing effect is induced by electric resonance triggered by electromagnetic waves. The proposed metamaterial absorber can be applied to radar stealth design for military targets such as naval vessels. The research methodology and approach demonstrate significant generalizability and engineering applicability.

Topology Optimization Enabled High Performance and Easy‐to‐Fabricate Hybrid Photonic Crystals

AbstractPhotonic crystals (PtCs) can confine and guide electromagnetic waves within specific frequency ranges, forming the foundation for promising optical applications. To numerically design PtCs with broad bandgaps, materials with high dielectric constants are favored. However, fabricating these high dielectric constant materials into microstructures is extremely challenging and it suffers from limitation of low fabricating resolution. To address this problem, this paper proposes hybrid microstructures composed of an easy‐to‐fabricate core and a high dielectric constant coating layer, which leverages the strength of both materials. This paper establishes a topology optimization algorithm to generate these PtCs with maximized bandgaps. Numerical examples demonstrate the effectiveness of the proposed method in generating optimized unit cells for both transverse magnetic (TM) and transverse electric (TE) modes. The hybrid PtCs offer unprecedented opportunities for the fabrication of optical devices, encouraging further research on multimaterial optical systems and advanced optimization methods to explore photonic bandgap materials beyond those offered by the current photonic technology.

Metasurfaces‐Enabled Advanced Multidimensional Imaging: Principle and Applications

AbstractThe efficient acquisition of multidimensional information—spatial, polarization, frequency, and phase of optical fields, is a key research focus. Metasurfaces, which are emerging as planar arrays of artificial nanostructures, offer significant advantages in advanced imaging due to their exceptional ability to manipulate electromagnetic waves through subwavelength optical resonators. Meanwhile, the rapidly developing computational imaging algorithms have also greatly enhanced the performance of metasurfaces in multi‐dimensional imaging. In this review, we focus on the research progress in metasurface‐empowered multidimensional imaging, including advanced spatial imaging, compact polarization imaging, high‐resolution spectral imaging, single‐shot phase imaging, and edge imaging. Their basic principles and imaging results will also be presented. Furthermore, a summary of several current challenges and anticipation in various future directions within this field will also be provided.

A dual-band broadband absorber using frequency selective surface for satellite antenna.

A dual-band broadband absorber based on frequency selective surface (FSS) is proposed. This double-layer absorber consists of two layers of FSS structure; each layer has a unique construction and plays its wave-absorbing function in different frequency bands. In the low-frequency band, layer I is a transmission channel, and layer II effectively absorbs electromagnetic waves. Furthermore, layer I exhibits significant absorption characteristics in the high-frequency band, whereas layer II provides effective reflection. The combination of the two layers results in a remarkably effective absorption. Its reflectivity below - 10dB covers a bandwidth of 5.5-14.8GHz and 22.9-33.1GHz, and its fractional bandwidth is 128%. The structure prevents external electromagnetic interference from affecting the antenna's performance, ensuring communication quality in critical frequency bands while reducing unwanted absorption in unwanted frequency bands. It is worth mentioning that the structure still has good stability under 45° oblique incidence. The physical mechanism is analyzed in detail by using an equivalent circuit model (ECM). The measurement results are in good agreement with those of simulation and ECM.

Effects of 1800MHz and 2100MHz mobile phone radiation on the blood-brain barrier of New Zealand rabbits.

In this study, the impact of mobile phone radiation on blood-brain barrier (BBB) permeability was investigated. A total of 21 New Zealand rabbits were used for the experiments, divided into three groups, each consisting of 7 rabbits. One group served as the control, while the other two were exposed to electromagnetic radiation at frequencies of 1800MHz with a distance of 14.5cm and 2100MHz with a distance of 17cm, maintaining a constant power intensity of 15 dBm, for a duration equivalent to the current average daily conversation time of 38min. The exposure was conducted under non-thermal conditions, with RF radiation levels approximately ten times lower than normal values. Evans blue (EB) dye was used as a marker to assess BBB permeability. EB binds to plasma proteins, and its presence in brain tissue indicates a disruption in BBB integrity, allowing for a quantitative evaluation of radiation-induced permeability changes. Left and right brain tissue samples were analyzed using trichloroacetic acid (TCA) and phosphate-buffered solution (PBS) solutions to measure EB amounts at 620nm via spectrophotometry. After the experiments, BBB tissue samples were collected from the right and left brains of all rabbits in the three groups and subjected to a series of medical procedures. Samples from Group 1 were compared with those from Group 2 and Group 3 using statistical methods to determine if there were any significant differences. As a result, it was found that there was no statistically significant difference in the BBB of rabbits exposed to 1800MHz radiation, whereas there was a statistically significant difference at a 95% confidence level in the BBB of rabbits exposed to 2100MHz radiation. A decrease in EB values was observed upon the arithmetic examination of the BBB.

A Polarization‐Insensitive and Adaptively‐Blazed Meta‐Grating Based on Dispersive Metasurfaces

AbstractThe diffraction efficiency of blaze gratings is optimized only at a specific frequency due to a fixed blaze angle, resulting in reduced and variable diffraction efficiencies over the working frequency band. Additionally, blazed gratings demonstrate polarization dependence due to their groove structures and the interaction of light with their surfaces. Consequently, designing gratings with constant diffraction efficiencies across a wide frequency bandwidth while maintaining polarization independence remains a challenge. Here, a design paradigm of dispersion engineerable meta‐grating inspired by orthogonal harmonic oscillations (OHO) is presented. Utilizing the OHO model, the phase dispersion of a metasurface can be precisely controlled, which applies to any unit cell featuring two orthogonal electromagnetic resonances. As a proof of concept, a polarization‐insensitive meta‐grating is showcased, where the blazed angle adapts with the incident frequency, ensuring broadband performance. In the experiment, the adaptively‐blazed grating measured an optimized and constant diffraction efficiency of ≈80% over the working wavelength range, i.e., 8.7–12.2 µm. The difference in diffraction efficiency between the two perpendicular linear polarization states remains within 4.6%. The proposed paradigm paves the way for meta‐device design based on precise dispersion engineering, which has potential applications in spectrometers, broadband beam forming and steering, hyperspectral imaging, etc.

Resonant conversion of axion dark radiation into terahertz electromagnetic radiation in a neutron star magnetosphere

In the strong magnetic field of a neutron star’s magnetosphere, axions coupled to electromagnetism develop a nonzero probability to convert into photons. Past studies have revealed that the axion-photon conversion can be resonantly enhanced. We recognize that the axion-photon resonance admits two parametrically distinct resonant solutions, which we call the mass-matched resonance and the Euler-Heisenberg assisted resonance. The mass-matched resonance occurs at a point in the magnetosphere where the radially-varying plasma frequency crosses the axion mass ωpl≈ma. The Euler-Heisenberg assisted resonance occurs where the axion energy satisfies ω≈(2ωpl2/7gγγγγB¯2)1/2. This second resonance is made possible though the strong background magnetic field B¯, as well as the nonzero Euler-Heisenberg four-photon self-interaction, which has the coupling gγγγγ=8α2/45me4. We study the resonant conversion of relativistic axion dark radiation into photons via the Euler-Heisenberg assisted resonance, and we calculate the expected electromagnetic radiation assuming different values for the axion-photon coupling gaγγ and different amplitudes for the axion flux onto the neutron star Φa. We briefly discuss several possible sources of axion dark radiation. Achieving a sufficiently strong axion flux to induce a detectable electromagnetic signal seems unlikely. Published by the American Physical Society 2024

A mechanical qubit.

Although strong nonlinear interactions between quantized excitations are an important resource for quantum technologies based on bosonic oscillator modes, most electromagnetic and mechanical nonlinearities are far too weak to allow for nonlinear effects to be observed at the single-quantum level. This limitation has been overcome in electromagnetic resonators by coupling them to other strongly nonlinear quantum systems such as atoms and superconducting qubits. We demonstrate the realization of the single-phonon nonlinear regime in a solid-state mechanical system. The single-phonon anharmonicity in our system exceeds the decoherence rate by a factor of 6.8, allowing us to use it as a mechanical qubit and demonstrate initialization, readout, and single-qubit gates. Our approach provides a powerful quantum acoustics platform for quantum simulations, sensing, and information processing.

Design and experimental demonstration of functional devices for energy manipulation in new analog acoustic computers

The development of new analog computers based on analog signals of electromagnetic or elastic waves has become a hot research topic in recent years. In this Letter, based on the concept of quantum state transfer, we study the process of energy transfer between acoustic cavities. Through the transformation from the temporal domain to the spatial domain, we further study the process of energy transfer between acoustic waveguides, and then we realize the applications of energy distributors and limiters in the acoustic system, which are the functional devices of wireless communication technology in new analog acoustic computers. We both simulationlly and experimentally demonstrate the effectiveness of the two applications. The energy distributor and limiter we proposed have the advantages of a relatively wide operating frequency range and adjustability. Our work shows the transfer mechanism of acoustic energy between different structures, which increases its potential application value in new analog acoustic computers.

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.

Chirality-induced phonon spin selectivity by elastic spin–orbit interaction

Spin and orbital degrees of freedom are crucial in not only fundamental particles but also classical waves such as optical systems, wherein the spin-orbit interaction (SOI) of light provides new perspectives for manipulating electromagnetic waves. Elastic waves possess similar spin angular momentum (SAM) and orbital angular momentum (OAM). However, the elastic counterpart of SOI remains unexplored, even for ubiquitous elastic waveguides (WG). Here, we demonstrate the existence of elastic SOI in helical WG. We prove that the torsion and curvature of helical WG induces synthetic gauge potentials in describing the elastic vibrations. Through analytical theory and simulations, we unveil the interplay among elastic SAM, intrinsic OAM, and extrinsic OAM, impacted by the elastic SOI. Importantly, results show that elastic SOI can introduce the Chirality-Induced Phonon Spin Selectivity. These findings advance our understanding of angular momentum physics in elastic waves and enable practical strategies for wave manipulation.

Plasma-Driven Conversion of 2D Graphene into 3D Pouch for Improved Electromagnetic Absorption Performance.

Graphene-based materials are ideal for electromagnetic wave-absorbing materials (EAMs) due to their strong electrical and dielectric losses with reduced thickness and weight. To enhance the electromagnetic wave absorption performance of these materials, additional components are often incorporated. However, this approach not only increases the complexity of the synthesis process but also complicates and destabilizes the control of the material properties. In this study, we successfully employed a one-step method to reduce graphene oxide and transform 2D graphene into a 3D pocket-like structure through plasma treatment. This unique 3D structure is induced by the formation of uneven defects on the surface due to plasma treatment. The distinctive pouch-like structure of the reduced graphene oxide achieved remarkable electromagnetic wave absorption properties. Specifically, the material demonstrated a minimum reflection loss of -38.65 dB at 7.14 GHz, with an effective absorption bandwidth of 5.13 GHz and a thickness of just 1.9 mm. These results highlight the potential of plasma processing as a rapid, efficient, and environmentally friendly approach for the continuous production of advanced EAMs, paving the way for greener manufacturing practices in the industry.

Computer Modeling Study of the Effects of Radio Frequency EM Radiation on Humans

Computer Modeling Study of the Effects of Radio Frequency EM Radiation on Humans

Neutrino oscillation in the presence of background classical sources

Abstract The presence of background classical sources affects a quantum field theory significantly in different ways. Neutrino oscillation is a phenomenon that confirms that neutrinos are massive fermions in nature, a celebrated result in modern physics. Neutrino oscillation plays an important role in many astrophysical observations. However, the interactions between the background classical sources with neutrinos are not often considered. In the present article, we show the effect of some classical sources, namely matter currents, electromagnetic waves, torsion, and gravitational waves on neutrino oscillation. It is shown explicitly that the above sources can change the helicity state of neutrinos during neutrino oscillation.

Discrete Bio-Hazard Model of EM Radiation for Crowded People

This study investigates the behaviour of electromagnetic (EM) waves in densely populated environments using a Multicomponent Discrete Propagation Model (MCDM). Our analysis focuses on four critical parameters: Specific Absorption Rate (SAR), Electrical Field, Skin Depth, and Effective Radiated Power (ERP) by working on crowd densities and frequencies relevant to mobile technologies. This study is the first to employ a Propagation Model for such an analysis, offering a novel approach. Through comprehensive simulations, we explore how variations in electrical field strengths impact SAR, skin depth, and ERP. The results are compared to established safety limits for whole-body SAR exposure, providing valuable insights for guidelines. This research aims to contribute to designing future electronic devices that minimize overall RF emissions. This innovative approach has the potential to improve public confidence in the safety of wireless technologies significantly

A new ultra-compact communications system across air-sea water based on ELF magnetic mechanical antenna

Abstract In this paper, a long-range trans-air-seawater medium communication system is proposed based on a small extremely low-frequency (ELF) mechanical antenna. We analyze the propagation characteristics of ELF electromagnetic waves in seawater and determine the paths of ELF electromagnetic waves propagating across domains. Equivalent models of various mechanical antennas are analyzed based on their operating principles. Based on the equivalent model, the transmission principle of mechanical antenna in transmitting across air-sea medium is analyzed, and finally the mechanical antenna with permanent magnet working horizontally is identified as the optimal choice. The above results are also verified by simulation. Experimental and simulation results verify the good performance of a horizontally operating permanent magnet mechanical antenna in transmitting across air-sea medium. The ELF-band transmission communication across air-sea medium based on binary code modulation is realized, and the farthest transmission distance can reach 200m in the experiment. Based on this system, transmission in air was also tested up to a distance of 1.5 km. The ELF transmission across air-sea medium based on a permanent magnet mechanical antenna can greatly facilitate cross-domain teleportation and ocean exploration.

The effect of filler distribution on electromagnetic properties of nanocarbon/magnetic particles/polymer composites

The type of multi-component fillers and their spatial distribution in conductive polymer-based composites greatly influenced their electrical properties, electromagnetic shielding efficiency (SE), and absorption capability, which require a deep understanding of how these properties improve with changes in the phase composition, content, and distribution of these fillers in the composite. In this study, three-phase polymer composite materials (CMs) with random (epoxy-based) and segregated (polyethylene-based) distribution of nanocarbon (graphite nanoplatelets GNP and carbon nanotubes CNTs) and magnetic (Fe and Co3O4) fillers have been developed. It was found that permittivity εr′ in the frequency range (40–60 GHz) increases sufficiently with the nanocarbon content and their values are slightly higher for random GNP-filled CMs (εr′=10–15 for 3–5 wt. % GNP) compared to CNT-filled CMs and much higher compared to segregated CMs (εr′=4–7 for 3–5 wt. % of nanocarbon). Dielectric loss tangent tanδ is increased with the nanocarbon content (especially for Fe-filled CMs) and sufficiently higher in segregated CMs compared to similar random composites. These enhanced tanδ values correlate with higher electromagnetic shielding efficiency due to absorption of segregated nanocarbon/magnetic/polyethylene CMs, for example, SEAd ≈ 18–23 dB/mm for 5 wt. %GNP. The most preferable for microwave absorption are random and segregated CMs with 2–3 wt. % GNP/30 wt. % magnetic filler: RLmin = −(27–35) dB, effective absorption bandwidth (EAB) Δf10dB=11.5–12.5GHz at a sample thickness of 0.5–0.7 mm. In CNT-based segregated CMs, |RLmin| and EAB values are lower compared with GNP-based CMs. The ability to manipulate these characteristics is important for obtaining good shielding and absorptive properties in the microwave range of electromagnetic radiation.