Spatio-spectral analyses of electromagnetic wave energy absorption and heating effect

Studies of magnetically dependent effects of nonresonant absorption of electromagnetic wave energy in the resonator of the X-band EPR spectrometer related to the superconductivity of metallic lead inclusions and microscopic structural defects in crystals of narrow-band semiconductors PbS1 – x and PbS1 – x:Mn have been performed. It is shown that nanoscale lead particles present in polycrystalline material PbS0.96 with a high content of sulfur vacancies at temperatures of 2.6–8 K manifest themselves as superconductors of the 2nd kind and demonstrate high thermomagnetic stability. It was found that in a single-crystal sample PbS0.996 with a significantly lower concentration of sulfur vacancies under the influence of the electric component of the microwave field in the resonator of the ESR spectrometer, non-periodic bursts of microwave power absorption associated with avalanches of Abrikosov vortices and demonstrating the absence of thermomagnetic stability of superconducting regions associated with defects in the crystal structure of the sample PbS0.996 are observed.

Efforts to produce microwave absorber materials that are inexpensive and environmentally friendly have become a means of greening the environment. The breakthrough can be focused on industrial waste and natural materials for functional purposes and how to enhance their performance. We successfully synthesized nickel slag/laterite soil (NS/LS) and nickel slag/iron sand (NS/IS) nanocomposites using a simple mechanical alloying technique, and the electromagnetic (EM) wave absorption capacities of the nanocomposites were measured using a vector network analyzer. The structural properties of the nanocomposites were analyzed by X-ray diffraction spectroscopy, where the results of the analysis showed that NS/IS has the largest crystallite size (15.69 nm) and the highest EM wave absorption performance. The optical properties of the nanocomposites were determined from their Fourier transform infrared spectra using the Kramers-Kronig relation. As determined through a quantitative analysis of the optical properties, the distance between the longitudinal and transversal optical phonon wavenumber positions (Δ(LO - TO) = 65 cm-1) is inversely proportional to the reflection loss. The surface morphologies of the nanocomposites were analyzed by scanning electron microscopy, and the particle diameters were observed by binary image and Gaussian distribution analyses. The nanocomposite surface exhibits a graded-like morphology, which indicates multiple reflections of the EM radiation, consequently reducing the EM interference. The best nanocomposite for an attenuated EM wave achieved a reflection loss of -39.14 dB at 5-8 GHz. A low penetration depth has implications for the electrical charge tuning of the storage and composite magnets. Finally, the EM absorption properties of NS/IS and NS/LS indicate a 2-mm-thick environmentally friendly nanocomposite for EM absorption.

A previously developed long-wavelength analysis is applied to ellipsoidal models of humans and experimental animals to obtain the distribution of tissue power absorption and average power absorption for different frequencies and orientations of the model with respect to the field vectors. Curves showing the distribution of absorbed power inside the model, and the average absorbed power versus frequency are presented for several species. Comparisons of calculated data with preliminary experimental data on monkeys are given. The theoretical results show that the power absorption in the ellipsoidal model is a strong function of frequency and orientation with respect to the incident plane wave field vectors. The quantitative data presented here are valuable for estimating tissue electromagnetic (EM) power absorption in experimental animals and humans. These data may also be used in extrapolating EM induced effects measured in animals to those expected in humans.

This paper presents the electromagnetic wave propagation characteristics in plasma and the attenuation coefficients of the microwave in terms of the parametersn e ,v, ω,L, ω b . The ϕ800 mm high temperature shock tube has been used to produce a uniform plasma. In order to get the attenuation of the electromagnetic wave through the plasma behind a shock wave, the microwave transmission has been used to measure the relative change of the wave power. The working frequency isf=(2∼35) GHz (ω=2πf, wave length λ=15 cm ∼ 8 mm). The electron density in the plasma isn e =(3×1010∼1×1014) cm−3. The collision frequencyv=(1×108∼6×1010) Hz. The thickness of the plasma layerL=(2∼80) cm. The electron circular frequency ω b =eB 0/m e, magnetic flux densityB 0=(0∼0.84) T. The experimental results show that when the plasma layer is thick (such asL/λ ≥10), the correlation between the attenuation coefficients of the electromagnetic waves and the parametersn e ,v, ω,L determined from the measurements are in good agreement with the theoretical predictions of electromagnetic wave propagations in the uniform infinite plasma. When the plasma layer is thin (such as when bothL and λ are of the same order), the theoretical results are only in a qualitative agreement with the experimental observations in the present parameter range, but the formula of the electromagnetic wave propagation theory in an uniform infinite plasma can not be used for quantitative computations of the correlation between the attenuation coefficients and the parametersn e ,v, ω,L. In fact, if ω ωp,v 2 ≪ ω2 (justv≈f), the measurements are much larger than the theoretical results. Also, we have measured the electromagnetic wave power attenuation value under the magnetic field and without a magnetic field. The result indicates that the value measured under the magnetic field shows a distinct improvement.

Ternary Mo2C/Co/C composites with enhanced electromagnetic waves absorption

Coincidence of features of emitted THz electromagnetic wave power form a single Josephson junction and different current components

(The Principle, Design, Manufacturing Production Process of Thermal Energy Directly into Electrical Energy Heat Energy Panels)

Multifunctional carbon nanofibers coated Co-Zn alloy nanoparticles composite for efficient energy conversion and microwave absorption

Electromagnetic wave absorption properties of Ni0.5Zn0.5Fe2O4–BaTiO3–epoxy composites

Multifunctional BiFeO3 composites: Absorption attenuation dominated effective electromagnetic interference shielding and electromagnetic absorption induced by multiple dielectric and magnetic relaxations

Exceptionally porous three-dimensional architectural nanostructure derived from CNTs/graphene aerogel towards the ultra-wideband EM absorption

Fabrication of magnesium ferrite microspheres decorated nitrogen-doped reduced graphene oxide hybrid composite toward high-efficiency electromagnetic wave absorption

Electromagnetic energy is the backbone of wireless communication systems, and its progressive use is considered to have a low but measurable impact on a wide range of biological systems. Even though a growing amount of data has reported electromagnetic energy absorption in humans along with subsequent biological effects, the consequences of electromagnetic energy absorption on plants have been insufficiently addressed. The higher surface to volume ratio along with the enormous water-ion concentrations makes the plant an ideal model to interact with non-ionizing electromagnetic radiation. In this study, controlled and periodic electromagnetic exposure of 1837.50 MHz, 2.75 W/m2 for 6 h a day on a popular rice variety (var. Satabdi) reduced the seed germination rate. The same dose of periodic electromagnetic exposure upregulated phytochrome B and phytochrome C gene transcripts in 12-day-old seedlings, whereas, in 32-day-old plants, the dose upregulated calmodulin and phytochrome C while the bZIP1 gene showed repression. However, the transcript abundance of bZIP1, phytochrome B, and phytochrome C genes was enhanced even in 12-day-old Satabdi seedlings following instantaneous short-duration (2 h 30 min) controlled electromagnetic exposure to 1837.50 MHz, 2.75 W/m2 . The reported responses in rice were observed below the international electromagnetic regulatory limits. Thus, rice plants perceived electromagnetic energy emitted by the wireless communication system as abiotic stress as per its response by upregulation or repression of known stress-sensing genes. Bioelectromagnetics. © 2020 Bioelectromagnetics Society.

Results of research of electromagnetic response of BaFe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">19</sub> hexaferrite at frequencies 34-250 GHz at room temperature are presented. At the vicinity of the frequency ~ 50 GHz the resonance absorption of electromagnetic wave energy was observed. We explain this by the presence of natural ferrimagnetic resonance in the effective field of magnetocrystalline anisotropy.

A theoretical analysis is made of the resonant absorption of RF electromagnetic wave energy in layered conductors having a quasi-two-dimensional electron energy spectrum. An analysis is made of the influence of possible drift of carriers into the conductor and their Fermi-liquid interaction on the position of the cyclotron resonance lines. A reason is given for the substantial difference between the cyclotron effective masses determined from the temperature dependence of the amplitude of the Shubnikov-de Haas oscillations and from measurements of the cyclotron resonance frequencies in [5–7]. It is shown that by means of an experimental investigation of cyclotron resonance in a magnetic field parallel to the layers, it is possible to find the carrier velocity distribution at the Fermi surface in layered organic conductors.