Electromagnetic Wave Propagation Research Articles

Investigation of Electromagnetic Wave Propagation in Triple Walled Carbon Nanotubes

This study examines the behavior of electromagnetic wave propagation in a unique and complex three-walled carbon nanotube structure. The structure is formed by nesting three distinct nanotubes, and the interactions between them are thoroughly analyzed, taking into account their varying electromagnetic, material, and nano properties. The structure is designed at a nanoscale to provide a comprehensive description of electromagnetic wave propagation, including the electromagnetic interaction between the second nanotube, located in the middle of the structure, and the other two nanotubes situated in both the inner and outer portions of the structure. This study presents novel findings that differ from existing literature on the subject, contributing to our understanding of this important area of research.

Parasitic modulation effect caused by dynamic plasma in low frequency

Abstract-dynamic plasma sheath can severely interfere with the communication of hypersonic vehicles during atmospheric reentry. Theoretical and experimental results show that low-frequency (LF) electromagnetic (EM) waves could penetrate the plasma sheath, building a feasible method to solve the “radio blackout” problem. This paper discovers that the propagation of LF EM waves in plasmas is still influenced by parasitic modulation effects. Compared to microwave frequencies, the impact of parasitic modulation effects on signal modulation patterns is more distinct for LF EM waves. In contrast to the microwave frequency range, where the rotation direction of QPSK signal constellation points changes with the ratio of plasma frequency to electromagnetic wave frequency, in the LF range, the constellation points undergo limited clockwise rotation. This phenomenon can be attributed to the unique magnetic field propagation mechanism of LF EM waves in dynamic plasmas. This paper analyzes the mechanism of this specific parasitic modulation effect and discovers a sinusoidal transformation relationship between amplitude attenuation and phase shift. Meanwhile, the experimental and simulation results proved that the time-varying plasma could cause the parasitic modulation effect of LF EM wave, resulting in a limited clockwise rotation of orthogonal phase-shift keying constellation points, which is consistent with the theoretical analysis.

Ground Penetrating Radar Survey of Arctic Polygonal Wedge Structures

Ground Penetrating Radar Survey of Arctic Polygonal Wedge Structures

Characteristics of the electromagnetic wave propagation in the magnetized plasma sheath and the practical method for blackout mitigation

Abstract “Magnetic window” is considered as an effective method to solve the communication blackout issue. COMSOL software package based on the finite element method is utilized to simulate the propagation of right-handed circularly polarized wave in the magnetized plasma sheath. We assume a double Gaussian model of electron density and an exponential attenuation model of magnetic field. The propagation characteristics of right-handed circularly polarized wave are analyzed by the observation of the reflected, transmitted and loss coefficient. The numerical results show that the propagation of right-handed circularly polarized wave in the magnetized plasma sheath varies for different incident angles, collision frequencies, non-uniform magnetic fields and non-uniform plasma densities. We notice that reducing the wave frequency can meet the propagation conditions of whistle mode in the weak magnetized plasma sheath. And the transmittance of whistle mode is less affected by the variation of the electron density and the collision frequency. It can be used as a communication window.

Power loss model of electromagnetic waves propagation in cell solutions by GHz electrical impedance spectroscopy

The propagation of GHz electromagnetic (EM) waves across cells in cell solutions has been analytically modeled and numerically calculated in order to elucidate the power loss in the boundary between dispersed medium and cell by establishing a theoretical model. Living and dead yeast cells are chosen as objects because of the simple cell structure and ease of observation under optical microscope. Through the model, the average power density of the incident wave S avi , reflected wave S avr , transmitted wave S avt , and ratio of the power loss ψ are calculated and compared to analyze the power loss of EM waves inside living and dead yeast cells by considering the impacts of frequency of EM wave, cell viability, concentration, and component structures of the cell. Results demonstrate decreased S avi, S avr , and S avt with rising frequency, especially noticeable below 100 MHz due to enhanced absorption from cell components. EM waves in living yeast cell solutions exhibit faster attenuation and stronger reflection compared to dead yeast cells, attributed to intact organelles and membranes intensifying absorption and scattering. The increasing cells concentration further attenuates EM waves. This work elucidates propagation and power loss of EM waves in cell solutions and provides an effective computational approach to optimize EM wave based biomedical applications.

Wireless Channel Model Based on Ray Tracing Algorithm in the Sea Environment

The maritime environment is complex and changeable, and an accurate maritime wireless channel model is particularly difficult to establish. This study investigates the sensitivity of a three-dimensional (3D) maritime ray tracing (RT) model for the use of the geometrical optics in radio channel characterizations of maritime environments. The channel measurement experiments are mainly carried out at three frequency points of 1.5, 1.8, and 2.5 GHz, and the simulation results of the model are compared and corrected with the measured received power. Analysis shows that the modified model simulation results at 1.5, 1.8, and 2.5 GHz frequency points are in good agreement with the actual measurement, and the RMS is within 7 dB. Moreover, the reverse RT algorithm has the advantages of fast calculation speed and high efficiency. The effects of the different sea conditions, frequencies, and distances on the propagation of electromagnetic waves are analyzed on the basis of this model.

The non-uniformity characteristics of the evaporation duct in the South China Sea based on CLDAS data

The non-uniformity of the evaporation duct has a significant impact on the propagation of electromagnetic waves. Based on the near real-time dataset from the China Meteorological Administration Land Data Assimilation System (CLDAS) and the National Centers for Environmental Prediction (NCEP) Climate Forecast System Reanalysis (CFSR) datasets, the non-uniformity characteristics of evaporation duct height (EDH) in the South China Sea (SCS) region at different distances of electromagnetic propagation and the main influencing factors of EDH non-uniformity are analyzed. The findings are given as follows. First, the SCS monsoon has a significant impact on the spatial and temporal distribution of EDH, particularly in the western coastal areas of Luzon Island and the eastern coastal areas of the Indochina Peninsula. Secondly, the non-uniformity of EDH is more pronounced in the western part of Luzon Island, the eastern coast of the Indochina Peninsula, and the sea-land boundary area of the Beibu Gulf. Besides, the non-uniformity of EDH in the western part of Luzon Island and the eastern part of the Indochinese Peninsula is greatly influenced by air-sea temperature difference and relative humidity. Finally, it is advisable to consider the influence of the non-uniformity of EDH when the distance of electromagnetic propagation in coastal areas exceeds 50 km. However, it can be disregarded within a range of 100 km on the broad ocean.

Electromagnetic guided waves in composite liquid crystal-based interfaces

We study an air–crown glass planar interface that includes a thin layer of a cholesteric liquid crystal doped with silver spheres of nanometer size. We propose a new theoretical model for the propagation of electromagnetic waves through the liquid crystal part and use the Marcuvitz–Schwinger form of the Maxwell equations to compute guided surface wave profiles. The results suggest the presence of anisotropic surface modes with negligible attenuation. The dependence of the surface wave parameters on the liquid crystal layer parameters can be used in liquid crystal-based sensors.

Varying coefficients in parallel shared-memory variational splitting solvers for non-stationary Maxwell equations

Direction-splitting implicit solvers employ the regular structure of the computational domain augmented with the splitting of the partial differential operator to deliver linear computational cost solvers for time-dependent simulations. The finite difference community originallye mployed this method to deliver fast solvers for PDE-based formulations. Later, this method was generalized into so-called variationals plitting. The tensor product structure of basis functions over regular computational meshes allows us to employ the Kronecker product structureo f the matrix and obtain linear computational cost factorization for finite element method simulations. These solvers are traditionally usedf or fast simulations over the structures preserving the tensor product regularity. Their applications are limited to regular problems and regularm odel parameters. This paper presents a generalization of the method to deal with non-regular material data in the variational splitting method. Namely, we can vary the material data with test functions to obtain a linear computational cost solver over a tensor product grid with nonregularm aterial data. Furthermore, as described by the Maxwell equations, we show how to incorporate this method into finite element methods imulations of non-stationary electromagnetic wave propagation over the human head with material data based on the three-dimensional MRI scan.

Research on Optimization Method of Evaporation Duct Prediction Model

The sea surface roughness parameterization and the universal stability function are key components of the evaporation duct prediction model based on the Monin–Obukhov similarity theory. They determine the model’s performance, which in turn affects the efficiency and accuracy of electromagnetic applications at sea. In this study, we collected layered meteorological and hydrological observation data and preprocessed them to obtain near-surface reference modified refractivity profiles. We then optimized the sea surface roughness parameterization and the universal stability function using particle swarm optimization and simulated annealing algorithms. The results show that the particle swarm optimization algorithm outperforms the simulated annealing algorithm. Compared to the original model, the particle swarm optimization algorithm improved the prediction accuracy of the model by 5.09% under stable conditions and by 9.97% under unstable conditions, demonstrating the feasibility of the proposed method for optimizing the evaporation duct prediction model. Subsequently, we compared the electromagnetic wave propagation path losses under two different evaporation duct heights and modified refractivity profile states, confirming that the modified refractivity profile is more suitable as the accuracy criterion for the evaporation duct prediction model.

Manipulation of random laser by the bandgap in three-dimensional SiO2 photonic crystals

Photonic crystals (PCs) are artificial structures with different dielectric constants that are arranged periodically in space and can control the propagation of electromagnetic waves of specific frequencies. The photonic bandgap can tune the photon state density, which is beneficial for the generation of random lasers (RLs). In this paper, a thin film of PMMA-doped DCJTB is spun-coated on a silicon dioxide (SiO2)PC to produce an RL. The PC is fabricated by a convenient dip-coating method with variable PBGs by changing the diameter of SiO2 nanospheres. By changing the position of the PBG gap, the RL emission peak can be effectively manipulated with an emission wavelength of up to 16 nm. By adding Au nanoparticles, the lasing performance is improved due to the surface plasmon resonance effect and strong photon scattering, where the emission intensity is increased by 191.9 %, and the threshold is decreased by 37.8 %. The imaging results show that the RL has low spatial coherence, which has a good application in speckle-free imaging. This study provides an effective method to produce a low threshold, high-quality RL with convenient manipulation of lasing properties, which opens the door for expanding its application in optoelectronic devices and speckle-free imaging.

Scalar and vector electromagnetic solitary waves in nonlinear hyperbolic media

In this paper, we investigate the problem of electromagnetic wave propagation in hyperbolic nonlinear media. To address this problem, we consider the scalar hyperbolic nonlinear Schrödinger system and its coupled version, namely hyperbolic Manakov type equations. These hyperbolic systems are shown as non-integrable. Then, we examine the propagation properties of both the scalar and vector electromagnetic solitary waves by deriving their exact analytical forms through the Hirota bilinear method. A detailed analysis shows that the presence of hyperbolic transverse dispersion provides an additional degree of freedom to prevent the formation of singularity in both the scalar and vector solitary wave structures in this hyperbolic nonlinear media. Besides this, we realize that the solitary waves in this media possess fascinating propagation properties which cannot be observed in conventional nonlinear media. We believe that the present study will be very useful in analyzing electromagnetic wave propagation in hyperbolic nonlinear metamaterials.

Wavefront distortion and compensation for weakly relativistic vortex beams propagating in plasma

The propagation of electromagnetic wave in plasma is one of the long-standing concerns in the field of laser plasma, and it is closely related to the researches of radiation source generation, particle acceleration, and inertial confinement fusion. Recently, the proposal of various schemes for generating intense vortex beams has led to an increasing number of researchers focusing on the interaction between intense vortex beams and plasmas, resulting in significant research progress in various areas, such as particle acceleration, high-order harmonic generation, quasi-static self-generated magnetic fields, and parametric instability. Compared with traditional Gaussian beams, vortex beams, featuring their hollow amplitudes and helical phases, can exhibit novel phenomena during propagating through plasma. In this work, we primarily focus on studying the influence of the propagation process on the wave structure of vortex beams before filamentation occurs. The three-dimensional particle-in-cell simulations show that weakly relativistic vortex beams exhibit wavefront distortion during their propagation in plasma. The distortion degree is closely related to the intensity of the electromagnetic wave and the propagation distance for a given plasma density. This phenomenon is theoretically explained by using a phase correction model that considers the relativistic mass correction of electrons. Additionally, we demonstrate that the wavefront distortion can be compensated for and suppressed by appropriately modulating the initial plasma density, as confirmed by three-dimensional particle simulations. The results of decomposing the wavefront into Laguerre-Gaussian (LG) mode components indicate that the wavefront distortion is primarily caused by high-order <i>p</i> LG modes, and it is independent of other <i>l</i> LG modes. Additionally, we extend the present investigation to the propagation of vortex beams in axially magnetized plasma, where the phase correction model can also effectively explain the occurrence of wavefront distortion. Our work can deepen the understanding of the interaction between plasma and strong vortex beams, and provide some valuable references for designing plasma devices serving as the manipulation of intense vortex beams in future research.

Electromagnetic waves propagation in thin heterogenous coaxial cables. Comparison between 3D and 1D models

<abstract><p>This work deals with wave propagation into a coaxial cable, which can be modelled by the 3D Maxwell equations or 1D simplified models. The usual model, called the telegrapher's model, is a 1D wave equation of the electrical voltage and current. We derived a more accurate model from the Maxwell equations that takes into account dispersive effects. These two models aim to be a good approximation of the 3D electromagnetic fields in the case where the thickness of the cable is small. We perform some numerical simulations of the 3D Maxwell equations and of the 1D simplified models in order to validate the usual model and the new one. Moreover, we show that, while the usual telegrapher model is of order one with respect to the thickness of the cable, the dispersive 1D model is of order two.</p></abstract>

The Impact of Electromagnetic Waves Propagation to the Dielectric Nanoparticles on Crude Oil Interfacial Tension Reduction for Oil Recovery: A Review

The presence of interfacial tension (IFT) force between crude oil and other fluids in reservoirs is one of the critical parameters that restrict the effective mobility of the oil and is continuously entrapped in reservoir pores. Reducing binding forces between oil and such fluids is one of the methods employed to improve oil productivity known as enhanced oil recovery (EOR). Various nanoparticles (NPs) have been utilized to reduce IFT. However, NPs encountered a challenge in terms of successful operation under a high temperature. Consequently, the NPs tend to segregate at the oil/ water interface which diminishes the IFT influences and more oil continuously entrapped. Recently, an innovative approach to enhance oil mobility was proposed by activating the charges of the NPs via electromagnetic (EM) wave propagation. Few analyses were reported using dielectric NPs with reasonable reductions to IFT. The dielectric properties of NPs are essential attributes corresponding to EM waves. During the EM wave exposure, the extra disruptions were generated at the fluid/oil interface that function as activating agents for the NPs resulting in the additional reduction for IFT. The present study provides a comprehensive review of the few results available, challenges that confronted the success of this novel approach, and admirable recommendations to improve the process in the future.

An Efficient and Accurate Algorithm for Electromagnetic Wave Propagation Modeling Based on Wavelet Transforms

An Efficient and Accurate Algorithm for Electromagnetic Wave Propagation Modeling Based on Wavelet Transforms

Ultra‐wideband imaging with an improved backward projection algorithm for far‐field applications

AbstractUltra‐wideband (UWB) radar imaging is widely used in penetration detection, target location and detection, and vital monitoring because of its high interference immunity and excellent target recognition with high resolution. In this paper, we report the design of a UWB stepper radar imaging system by using a vector network analyzer and a specially designed novel Vivaldi antenna for far‐field imaging applications. An anti‐attenuation backward projection (AA‐BP) algorithm is proposed to alleviate the attenuation impact of electromagnetic wave propagation. The AA‐BP algorithm and the specially designed Vivaldi antenna are jointly applied in our experiments on multiple targets through wall imaging in both free space and multiple‐path propagation environments. The experimental results show that our reported imaging system achieves desirable performances of far‐field imaging.

Transient Simulation of Electromagnetic Wave Propagation in Plasma Based on Dynamic Drude Model

Transient Simulation of Electromagnetic Wave Propagation in Plasma Based on Dynamic Drude Model

Evaluation of Antenna Pattern Measurement of HF Radar using Drone

The High-Frequency Radar (HFR) is an equipment designed to measure real-time surface ocean currents in broad maritime areas.It emits radio waves at a specific frequency (HF) towards the sea surface and analyzes the backscattered waves to measure surface current vectors (Crombie, 1955; Barrick, 1972).The Seasonde HF Radar from Codar, utilized in this study, determines the speed and location of radial currents by analyzing the Bragg peak intensity of transmitted and received waves from an omnidirectional antenna and employing the Multiple Signal Classification (MUSIC) algorithm. The generated currents are initially considered ideal patterns without taking into account the characteristics of the observed electromagnetic wave propagation environment. To correct this, Antenna Pattern Measurement (APM) is performed, measuring the strength of signals at various positions received by the antenna and calculating the corrected measured vector to radial currents.The APM principle involves modifying the position and phase information of the currents based on the measured signal strength at each location. Typically, experiments are conducted by installing an antenna on a ship (Kim et al., 2022). However, using a ship introduces various environmental constraints, such as weather conditions and maritime situations. To reduce dependence on maritime conditions and enhance economic efficiency, this study explores the possibility of using unmanned aerial vehicles (drones) for APM. The research conducted APM experiments using a high-frequency radar installed at Dangsa Lighthouse in Dangsa-ri, Wando County, Jeollanam-do. The study compared and analyzed the results of APM experiments using ships and drones, utilizing the calculated radial currents and surface current fields obtained from each experiment.

Classical radiation fields for scalar, electromagnetic, and gravitational waves with spacetime-symmetry breaking

An effective field theory framework is used to investigate some Lorentz-violating effects on the generation of electromagnetic and gravitational waves, complementing previous work on propagation. Specifically we find solutions to a modified, anisotropic wave equation, sourced by charge or fluid matter. We derive the radiation fields for scalars, classical electromagnetic radiation, and partial results for gravitational radiation. For gravitational waves, the results show longitudinal and breathing polarizations proportional to coefficients for spacetime-symmetry breaking.