High Frequency Electromagnetic Waves Research Articles

Nano FeCoNi-based high-entropy alloy for microwave absorbing with high magnetic loss and corrosion resistance

With the development of modern communication and military technology, the protection of electromagnetic wave pollution and radar stealth technology have been widely concerned. In this background, the magnetic metals were widely used due to the strong ferromagnetism, which can induce strong magnetic loss to the electromagnetic wave. However, it remains challenging to precisely control the wave-absorbing performance of individual magnetic metals, and there are issues with poor corrosion resistance and high temperature resistance. Therefore, the alloy powders based on Fe, Co, and Ni in this work were prepared by wet chemical method at room temperature. Different from most of the traditional powder metallurgy methods, the wet chemical method enables us to obtain binary, ternary and quaternary alloys with a nanometer-scale and uniform distribution, all products have a microscopic morphology of 300–500 nm spheres. The FeCoNi alloy powder shows an effective absorption band (RL<-10 dB) of 7 GHz in the high frequency electromagnetic wave range at an ultrathin thickness of 1.5 mm, which has a high temperature magnetism (Tc >900 K) and excellent corrosion resistance. Further doping of Cu to form a quaternary alloy can improve the corrosion resistance and maintain the original wave-absorbing properties, while doping of Mo and Sn can adjust the position of the effective absorption bandwidth.

Magnetodielectric, elastic, Rietveld refinement and absorption properties of Nd–Cu co-doped Co–Zn nano ferrites: Development of meta-absorbers for wide frequency regime

Currently, Electromagnetic (EM) pollution is harmful to human health because of the generation and propagation of high-frequency EM waves from electronic devices. The absorbing materials with outstanding properties are highly desirable. Meta-absorbers with extraordinary electromagnetic wave absorption, outstanding EM shielding ability, and featured dissipation efficiency are still worth challenging in the surrounding environments. The meta-absorbers were fabricated, designed, and simulated to address the challenges. Nd–Co co-doped Co–Zn spinel nano ferrites (Co0.5Zn0.5-xCuxFe2-yNdyO4 with x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5, y = 0.00, 0.02, 0.04, 0.06, 0.08, 0.10) were prepared. XRD, FESEM, FTIR, and VSM were used to study the structure, phase, vibrational, elastic, and magnetic features of the Nd–Co co-doped Co–Zn ferrites, respectively. Rietveld refinement of the Nd–Co co-doped Co–Zn ferrites was evaluated by FullProf software. Wyckoff locations and occupancy of the already present cations and anions were refined. The bond lengths and unshared-shared edges were determined using the Bertaut method. The detailed phase occurrence, force constant, and elastic features of Nd–Co co-doped Co–Zn ferrites were also investigated. The mixed shapes of grains like elliptical, circular, and hexagons were noticed from FESEM images. The magnetization and coercivity were reduced with the Nd–Cu doping. Switching field and high-frequency response were also presented for the Nd–Cu co-doped Co–Zn ferrite. The dielectric properties like complex permittivity and permeability depicted higher response at high frequency due to interfacial polarization in prepared ferrites. The reflection loss (RL) of −74.1 dB was noticed at 1.99 GHz for x = 0.4, y = 0.08. However, the reflection loss of −63.9 dB at 2.24 GHz was observed for x = 0.5, y = 0.1. Meta-absorbers of Nd–Cu co-doped NiZn were designed and simulated. The wideband absorptivity is depicted for Nd–Cu co-doped CoZn ferrite as substrate material at x = 0.0 y = 0.00, x = 0.1 y = 0.02, and the absorptivity remains highest for θ = 0 deg. The absorptivity significantly reduces with the increase of incidence angle. Meta-absorbers based on Nd–Cu co-doped Co–Zn ferrites are good future candidates for EMI (electromagnetic interference), MLCIs (multilayer chip inductors), electromagnetic shielding, and 5G-mobile antenna purposes in high-frequency applications.

Connection Between Gravity and Quantum World

Gravity is the most important force in cosmology. A lot of research deals with it, but we only know its perceptible properties. Two basic descriptions of gravity are accepted today. One is based on classical physics based on Newton\’s theory. The other is the theory of gravity described by Einstein. However, another description of gravity is also possible. Gravitation can also be described in other ways using the equations of Kepler, Newton, Coulomb, and Maxwell. Using their equations, it can be deduced that: The magnitude of the gravitational force field is not determined only by mass. It depends on the speed of the mass. It depends on the size of the gravitational field in which the mass moves Newton\’s and Coulomb\’s laws are equivalent. This has already been determined by several researchers. It was also conducted by Constantin Meis. Newton\’s, Coulomb\’s, Maxwell\’s law can be used to determine a new cosmic constant. It can be counted on in the Solar System, but also in the Milky Way. Denote by μ_2 and √ (μ_2) This constant connects the macro world and the micro or quantum world. This constant can also be calculated using Coulomb\’s and Maxwell\’s equations Maxwell\’s and Coulomb\’s equation can be used to determine the resultant of the associated vibrating charges for each mass and celestial body. Coulomb\’s law can also be used to accurately determine the force effect between masses. Even the force effect between celestial bodies can be determined with it. This is exactly the same as the force effect calculated by Newton\’s law. For a mass of 1 kg, we get exactly Cavendish\’s measurement result with Coulomb\’s law. Already in the 20th century, it was suggested that there is a connection between gravity and the electromagnetic field. This has already been conducted by Constantin Meis and Takaaki Musha and B. Ivanov. Gravitational constant can not only be measured, but also calculated in several ways. This has already been determined by several researchers. The gravitational constant can also be calculated using the mass and its speed. But it can also be calculated using the Coulomb constant and μ_2 The gravitational force field for a given mass or celestial body can be calculated using √(μ_2) and the charge of the mass. The speed of a given planet can be calculated using its charge and √ (μ_2) Based on the derivations, gravity is a force field that has an electric force field component. Therefore, it can be the carrier medium of electromagnetic waves. And so is the carrier of light If we assume that the gravitational force field is a very high frequency electromagnetic wave, then we also understand that gravity is unipolar.

Peculiarities of leakage of the electromagnetic waves from striations

It is well-known that an ordinary (O-mode) high frequency (HF) electromagnetic (EM) wave radiated into the ionosphere generates in the F-region upper-hybrid resonance (UHR) oscillations trapped in small-scale elongated plasma depletions (striations). Striations are not ideal resonators for UHR oscillations. There is some leakage of the HF energy from striations in the form of Z-mode waves. This result obtained in the quasi-electrostatic approximation is partly reconsidered in the present paper. It is shown in the 2D case that two EM waves (instead of one Z-mode) propagate from each side of a striation. The lowest eigenmodes of the electrostatic oscillations trapped in a striation excite at particular heights Z-mode waves that propagate significantly higher than the reflection height of the initial O-mode wave. This result exists for different angles of the O-mode radiation with respect to the vertical (both more and less than the critical angle).

The impact of quantized magnetic pressure on the stimulated Brillouin scattering of electromagnetic waves

Within the frame work of Landau quantization theory of Fermi gas, we formulate here the exotic physics of magnetic stimulated Brillouin scattering instability (MSBS) arising due to the nonlinear interaction of high frequency electromagnetic waves (EMWs) with degenerate, strongly magnetized electron-ion plasma. Quantum magneto hydrodynamic model (QMHD) is followed to develop the basic differential equations of quantized magnetosonic waves (QMWs) in the presence of super strong magnetic (SSH) field, whereas Maxwell equations are used to derive the governing differential equation of pump EMWs. The nonlinear interaction of EMWs and QMWs is addressed by employing the phasor matching technique. The obtained dispersion relation of MSBS shows that for a fixed density of fermions, the SSH field alone suppresses the MSBS instability as a function of quantized magneto ion velocity (C He ) and the Alfven speed (V A ) via three-wave decay and modulational instabilities. However, for particular condition the MSBS instability is found to increase as a function of SSH field. Next, the analytical results are verified numerically and graphically for soft x-rays in the environment of neutron star. The present MSBS analysis may be critical in neutron stars, radio pulsars and magnetars having super strong magnetic field i.e. even larger than the quantum threshold value i.e, H ∼ 4.4 × 1013 G, or in any application where the enhancement or suppression of SBS may be important.

Diaphragmatic Injury with Empyema Development after Microwave Ablation of a Liver Dome Lesion.

Percutaneous microwave ablation (MWA) of the liver is a minimally invasive procedure that utilizes high frequency electromagnetic waves to generate heat and induce tumor necrosis. MWA has been proven to be a safe and effective treatment option for primary and metastatic liver tumors. The treatment of liver dome lesions can present a technical challenge due to the proximity of the hepatic dome to the diaphragm and lung parenchyma. In this report, we present a case of diaphragmatic injury and subsequent empyema following MWA of a liver dome lesion.

Interaction of the high frequency waves in the vicinity of the ionospheric window

It is well-known that an ordinary high frequency electromagnetic (EM) wave radiated into the ionosphere at the Spitze angle is totally transformed at the reflection height (z0) into the Z-mode. This mode, in turn, penetrates deeper into the ionosphere and it is reflected at some height (zref) usually significantly higher than the O-mode reflection height. This result is reconsidered in the present paper. It is argued that the wave appearing as a continuation of the propagating upward quasi-electrostatic wave changes the direction of motion along the vertical axis slightly above z0 and takes the form of the down-going wave. This wave is excited in the vicinity of the height z0 due to the phase resonance with the up-going O-mode wave which transforms into the Z-mode propagating upward. Thus, the ionospheric window is not totally transparent for the O-mode radiated at the Spitze angle. The up-going O-mode wave loses some part of its energy due to excitation of the down-going EM wave. This wave, in turn, propagates to the ground as the O-mode wave.

The effect of collisions on the multi-fluid plasma Richtmyer–Meshkov instability

The Richtmyer–Meshkov instability (RMI) results from the impulsive acceleration of a density interface where the RMI itself or the acceleration is perturbed. The RMI is ubiquitous in shock environments and may arise due to an interface of fluid species, isotopes, temperature, or more. The plasma RMI can be significantly influenced by electromagnetic effects and can be modeled more accurately by a multi-fluid plasma (MFP) model rather than conventional magnetohydrodynamics, though with increased computational expense. MFP modeling of the plasma RMI has revealed many phenomena but has only been completed within the ideal regime. Modeling the effects of elastic collisions is vital for understanding the behavior of the instability in a dense plasma. The Braginskii transport coefficients provide theoretically based relations modeling thermal equilibration, inter-species drag, viscous momentum- and energy-transfers, and thermal conductivity. Our numerical simulations of the MFP RMI with these relations show that the key changes from the ideal case are (1) reduction of relative motion between the ion and electron fluids (consequently affecting the self-generated electromagnetic fields), (2) introduction of anisotropy in momentum and energy via transport coefficients, and (3) damping of high frequency electromagnetic waves and plasma waves. Under the conditions studied, the net effect is a reduction in the MFP RMI amplitude width and the growth rate to levels approaching the neutral fluid instability, as well as a reduction in large scale perturbations along the ion fluid density interface, a positive for inertial confinement fusion efforts. There are, however, two important caveats: small-scale density interface perturbations remain, and the conditions simulated are a few relevant points in a large parameter space that requires further investigation.

Influence of specific electrical resistance on the heating of metal plates exposed to high frequency electromagnetic waves

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

Research on Integrated Sensor Technology of Electrostatic Discharge Ultrasonic and High-Frequency Electromagnetic Wave for Spacecraft Space Equipment

Research on Integrated Sensor Technology of Electrostatic Discharge Ultrasonic and High-Frequency Electromagnetic Wave for Spacecraft Space Equipment

The Interaction between High Frequency Electromagnetic Waves with Plasma and the Effect of Negative Ions Existence on the Power Absorption Capability

The interaction between the incident, high frequency, electromagnetic waves with plasma layer shows that the existence of negative ions and the non-linear effect reduces the power absorption capability of the plasma. In this research we study and discuss all parameters of the great influence in this process depending on many important equations, like the Maxwell equations, current response of the plasma equation, multi – fluid momentum equation and the continuity equation. Numerical simulations based on the finite- difference- time- domain approximation to multi- fluid equations for the positive ions, negative ions and electrons are used to study high frequency electromagnetic waves propagation and absorption in an unmagnetized plasma layer. A good agreement in the comparison between the simulations in this work and the experimental results in the previous works is shown.

Radar—CubeSat Transionospheric HF Propagation Observations: Suomi 100 Satellite and EISCAT HF Facility

AbstractRadio waves provide a useful diagnostic tool to investigate the properties of the ionosphere because the ionosphere affects the transmission and properties of high frequency (HF) electromagnetic waves. We have conducted a transionospheric HF‐propagation research campaign with a nanosatellite on a low‐Earth polar orbit and the EISCAT HF transmitter facility in Tromsø, Norway, in December 2020. In the active measurement, the EISCAT HF facility transmitted sinusoidal 7.953 MHz signal which was received with the High frEquency rAdio spectRomEteR (HEARER) onboard 1 Unit (size: 10 × 10 × 10 cm) Suomi 100 space weather nanosatellite. Data analysis showed that the EISCAT HF signal was detected with the satellite's radio spectrometer when the satellite was the closest to the heater along its orbit. Part of the observed variations seen in the signal was identified to be related to the heater's antenna pattern and to the transmitted pulse shapes. Other observed variations can be related to the spatial and temporal variations of the ionosphere and its different responses to the used transmission frequencies and to the transmitted O‐ and X‐wave modes. Some trends in the observed signal may also be associated to changes in the properties of ionospheric plasma resulting from the heater's electromagnetic wave energy. This paper is, to authors' best knowledge, the first observation of this kind of “self‐absorption” measured from the transionospheric signal path from a powerful radio source on the ground to the satellite‐borne receiver.

PD Flexible Built-In High-Sensitivity Elliptical Monopole Antenna Sensor.

In view of the insufficient signal detection sensitivity of Gas Insulated Switchgear (GIS), partial discharge (PD), ultra-high frequency (UHF), and failure to conform with GIS surface structure when the existing rigid stereo structure UHF sensor is built in, this paper, using rectangular patch antenna equivalent technique, trapezoidal ground plane technique, and coplanar waveguide (CPW) feed line index asymptotic linearization technique, conducts research on a flexible built-in high-sensitivity elliptic monopole antenna. The flexible antenna, with a thickness of only 0.28 mm, can be kept at a voltage standing wave ratio (VSWR) of less than three in the 300 MHz to 3 GHz band under the curvature radius of 0, 100, 300, and 500 mm, and at less than two in the 650 MHz to 3 GHz band. Through the true 220 kV-GIS partial discharge experimental platform built to analyze the high frequency electromagnetic wave detection performance of the built-in flexible antenna, it is shown that the flexible built-in high-sensitivity elliptical monopole antenna designed in this paper can effectively detect the characteristic signals of high-frequency electromagnetic waves emitted by partial discharges with an average discharge amount below 10 pC.

Nonlinear optical absorption and optically detected electrophonon resonance in GaAs based n − i − p − i superlattices

The quantisation of electronic energy into subbands in low-dimensional structures originates many interesting physical effects, one of which is the electrophonon resonance effect. In this work, we investigate the electrophonon resonance by theoretically calculating the optical absorption power in n − i − p − i superlattices (SLs) subjected to a high frequency electromagnetic wave. The absorption power is calculated up to the first-order nonlinear term using the projection operator technique taking account of the effect of electron – optical phonon interaction. Numerical results are obtained and discussed for the GaAs:Si/GaAs:Be SL. The linear and nonlinear optically detected electrophonon resonance (ODEPR) peaks are observed in the absorbance. The full width at half maximum (FWHM) of ODEPR peaks increases with increasing the doping concentration as well as temperature. In particular, the results show that the two-photon absorption is of great importance and should be considered in nonlinear optics. This investigation provides a theoretical basis for potential applications of n − i − p − i SLs in optoelectronic devices.

Exposure effects of non-ionizing radiation of radio waves on antimicrobial potential of medicinal plants

The high frequency electromagnetic (EM) waves have been proven as potent environmental polluters. The radio towers are considerably increasing to cater to the growing telecommunication requirements. The presented research focuses on the investigation of EM waves on antimicrobial potential of pharmaceutically important medicinal plants viz. Tulsi (Ocimum sanctum L.) and Brahmi (Bacopa monnieri). The similar work has not been reported till date at the best of our knowledge. The medicinal plants were exposed to EM waves of 900 MHz possessing a 1.9 mG magnetic field. Our former investigation on plant physiology gave deteriorative effects on selected plants physiology in terms of growth, chlorophyll content, protein and carbohydrate content. In the presented article, the antimicrobial activity of two plants was inspected through various bacterial and fungal species. In case of B. monnieri, investigations revealed raise in Zone of Inhibition (ZOI) for both the bacterial and fungal strains in the range of 50%, whereas for O. sanctum increase of 63.26% and 59.42% ZOI for bacterial and fungal strains were noted respectively upon 24 h of exposure. Minimum Inhibitory Concentration (MIC) also decreased for 24 and 48 h of exposure. The transient raise in antimicrobial activity indicated the induction of plant defense system which can be considered as positive influence of short term radiation on medicinal properties of plants. Both plants exhibited the highest antimicrobial potential for E. coli and P. chrysogenum showing a prominent decline after 72 h of exposure. A substantial decline in antimicrobial in MIC of B. monnieri reported was 211% against E. coli and 166% against P. chrysogenum upon 144 h of exposure compared to control plants. The antimicrobial potential of O. sanctum was also decreased upon radiation, which is having a 392% reduction against E. coli and a 225% reduction against P. chrysogenum upon 144 h of exposure. The noteworthy deteriorative effects of radio waves on antimicrobial potential have been observed for both the medicinal plants.

Optimization Design and Development of UHF Antenna for PD Detection in Substation

In this paper, a directional logarithmic periodic antenna is designed to meet the application requirements of local discharge detection in substation.The model of log-periodic dipole antenna was established by using high frequency electromagnetic wave simulation software, and the effects of dielectric substrate thickness, dielectric constant of dielectric substrate and patch size parameters on antenna return loss and standing wave ratio were analyzed.Finally, the dielectric substrate thickness of the antenna is 1.6mm, the material is TEflon, and the width of the assembly line is 4mm.According to the selected antenna type and size, the uHF signal receiving antenna is manufactured.

Distribution of the Density of Heat Sources Originating in an Oil-Saturated Bed on Absorption of High-Frequency Acoustic and Electromagnetic Waves

Distribution of the Density of Heat Sources Originating in an Oil-Saturated Bed on Absorption of High-Frequency Acoustic and Electromagnetic Waves

Ohmic and Diamagnetic Currents Contribution on the Electromagnetic Penetration Depth of a Conducting Surface

Due to its conducting electron, metal is a good reflector for electromagnetic wave. An electromagnetic wave penetrating a metallic surface has a finite penetrating depth. There are two limit that are well studied in the physics textbooks. They are high frequency electromagnetic wave penetrating a metal with small conductivity and a static (low frequency) field penetrating a superconductor (metal with infinitely large conductivity). In this article we study the intermediate regime between these two limits. By setting the electric current density as the total sum of both Ohmic and Diamagnetic currents, we derive the penetration depth in the intermediate regime., we show the transition between these two limits.

Off/on switchable smart electromagnetic interference shielding aerogel

Summary Smart electromagnetic interference (EMI) shielding materials with tunable EM wave response characteristics are attractive for future EM devices. Here, we report an off/on switchable EMI shielding material that can be tuned from EM wave transmission to shielding and vice versa by mechanical compression and decompression. This smart material is prepared by filling conductive carbon nanoparticles into wood-derived lamellar carbon aerogel, showing reversible compressibility and strain-sensitive conductivity. The original aerogel has good impedance matching and low dielectric loss, allowing the EM wave to pass through. Mechanical compression enables the carbon nanoparticles to establish highly conductive pathways in the aerogel, which significantly increases the conductivity of aerogel and thus activates its EMI shielding performance. This function switch is reversible by repeatedly compressing and decompressing the aerogel. The availability of such a never-before-realized off/on switchable EMI shielding material provides an opportunity for the development of advanced smart EM devices.

Industrial applications of selected JFS articles

Industrial applications of selected <i>JFS</i> articles