Analysis Of Shielding Effectiveness Research Articles

Tailored eutectic alloy coating for enhanced EMI and X-ray protection by basalt fiber CNT/epoxy composite

In this study, eutectic-Bi–Sn-coated basalt fiber (BF)-reinforced carbon nanotube (CNT)/epoxy hybrid composites were fabricated for dual functionality, i.e., in managing and shielding clinical X-ray radiation and electromagnetic interference (EMI). BF mats were coated with Bi–Sn nanoparticles and subsequently layered with multi-walled CNTs mixed epoxy resin using the vacuum-assisted resin transfer method. High resolution field emission scanning electron microscopy revealed a good dispersion of Bi–Sn nanoparticles over BF and, CNTs within the epoxy matrix. X-ray diffraction analysis confirmed the presence of Bi–Sn, basalt, and CNT phases in the composites. High-resolution Raman spectroscopy revealed characteristic peaks corresponding to the CNTs, epoxy, and Bi–Sn phases. EMI total shielding effectiveness (SET) analysis in the X-band frequency range (8.2–12.4 GHz) demonstrated that the Bi–Sn/BF/CNT/epoxy (S3) exhibits the highest SET value of 30.4 dB, which is attributable to the synergistic effect of the Bi–Sn coating and CNT filler. Analysis of X-ray-radiation leakage revealed that all the composite samples effectively attenuated X-rays with minimal leakage, limited to 6.8 mR. These results indicate the potential of these composites for applications as eco-friendly, non-toxic, and lead-free various industries including healthcare, electronics, aerospace, and defense.

An Efficient Surface Integral Equation-Method of Moments for Analysis of Electromagnetic Shielding Effectiveness of a Perforated Isotropic and Lossy Enclosure

An Efficient Surface Integral Equation-Method of Moments for Analysis of Electromagnetic Shielding Effectiveness of a Perforated Isotropic and Lossy Enclosure

Construction of a simulation model of electromagnetic shielding clothing for shielding effectiveness analysis

Electromagnetic shielding (EMS) clothing is mainly studied for its shielding effectiveness (SE) through practical testing at present, which has many problems such as large experimental error and time and labor consumption. This paper proposes a method for constructing a simulation model of EMS clothing based on feature section replacement. Firstly, a human body model based on an elliptical truncated cone is established. A feature section of the key parts is built according to the morphological characteristics of the human body. Then a clothing structure model is established by replacing the corresponding sections in the elliptical truncated cone model with these feature sections. A digital description method for the model is given. The finite integral method is selected to calculate the SE of each test part when the clothing is completely closed, and the clothing contains holes and seams. By comparison with the measured value, it is concluded that the results of the constructed simulation model are in good agreement with the measured values. This paper establishes a new method to study the SE of EMS clothing, which provides a new approach for the design, production, evaluation and related research of EMS clothing.

Time-Domain Shielding Effectiveness Analysis Based on DGTD Method Accelerated by Local Time-Stepping and Parallel Techniques

The discontinuous Galerkin time-domain (DGTD) method accelerated by local time-stepping (LTS) and parallel techniques is employed to analyze the time-domain shielding effectiveness (TDSE) of metallic enclosures. The detailed formulations and implementation procedures of the DGTD method and LTS and parallel techniques are introduced. Numerical results validate the correctness of the proposed method. Moreover, the influence of various design parameters of the metallic enclosure, including aperture dimensions, wall thickness, spacing of aperture arrays, etc., on the TDSE are analyzed by the proposed method. Some rules are given for the design of the enclosure with rectangular apertures from the perspective of TDSE. The proposed method provides an extremely powerful tool for the evaluation of TDSE.

Analysis of radiation shielding effectiveness of hydride and borohydride metals for nuclear industry

Hydrogenous materials are of great interest in nuclear industry because of the ability of hydrogen to slow-down neutrons. In comparison with common hydrogenous materials, metal hydrides highly enriched with hydrogen at high temperatures and good mechanical properties. This study concerns on evaluation the requirements for photons, charged particles and fast neutrons shielding parameters for several types of hydride and borohydride metals. Firstly, photons shielding ability of these materials were examined using Phy-X/PSD program. Assigning the attenuation factors of photons were evaluated for an energy range (1 keV–100 GeV). Secondly, the charged particle (electron, proton and alpha particle) interactions were examined by using ESTAR (Stopping Powers and Ranges for Electrons) and SRIM (The Stopping and Range of Ions in Matter) programs. Finally, fast neutron attenuation was tested by calculating the removal cross-sections (ΣR) for neutron with energy 4.5 MeV. The dependence of photons, charged particles and fast neutrons parameters on the constituent of tested samples was given and discussed. The obtained results through this work show that, the shielding proficiency parameters depend on the energy of the incident radiation and chemical constituents of the examined materials. As well as, these results showed that BaH2, ZrH2, VH2 and TiH2 samples own a good shielding performance compared to the other investigated samples.

Synthesis and microwave absorption studies on 2D graphitic carbon nitride loaded polyaniline/polyvinyl alcohol nanocomposites

A light weight electromagnetic interference (EMI) shielding and microwave absorbing composite films has been developed by loading varying weight content of graphitic carbon nitride (g-C3N4) nanosheets and polyaniline (PANI) into polyvinyl alcohol (PVA) matrix. The prepared PVA/PANI/g-C3N4 (1%, 3%, 5%) composites has been subjected to FTIR, X-Ray powder diffraction, SEM, Thermal studies, Dielectric studies and electromagnetic shielding effectiveness (EMI SE) analysis. The PVA/PANI/g-C3N4 (1%, 3%, 5%) composites was discovered to have improved electrical conductivity, dielectric loss, and dielectric constant. It is observed from the SEM images that the sheet layers of g-C3N4 are wrapped by the polymer matrix and the morphology to PVA/PANI composite in the g-C3N4 indicates homogeneous blending of PVA/PANI without any phase separation and has porous in it. The PANI/g-C3N4 fractured surfaces present are smooth but irregular in appearance indicating good compatibility between the PVA and PANI matrices. The dielectric properties was found to increase on increasing the concentration of the g-C3N4 nanofiller and reached a maximum of 9.8 × 106 at 1 MHz for 3% g-C3N4 in PVA/PANI. The incorporation of g-C3N4 into PVA/PANI enhanced the conductivity and the 5% g-C3N4 loaded composite film exhibited a conductivity value of 0.043 S/cm at 1 MHz. The PVA/PANI/g-C3N4 (1%, 3%, 5%) composites exhibited potential EMI SE values ranging from 24 to 35 dB at 8.6 GHz and from 42 to 63 dB at 12.4 GHz, for instance the PVA/PANI/g-C3N4 5% composite showed highest value of 63 dB at 12.4 GHz. The PVA/PANI/g-C3N4 5% exhibits the maximum highest reflection loss 8 GHz–12 GHz in which the higher absorption of −36 dB is observed at 10.3 GHz of the X-band region.

Near-Field Scanning Based Shielding Effectiveness Analysis of System in Package

The electromagnetic interference (EMI) problems are crucial for system-in-package (SiP) due to the high demand of miniaturization and dense integration. Shielding methods are generally employed to protect SiP from EMI, through assessing the key performance index, i.e., shielding effectiveness (SE). In this article, the SE of a SiP is evaluated by using near-field scanning method. The SEs derived by using maximum near-field values and average near-field values are comparatively analyzed. The difference in near-field patterns of the unshielded and shielded SiPs may incur overestimation of the SE by using maximum field values. Both simulation and measurement results manifest that the gap between SiP and printed circuit board (PCB) will significantly change the radiation pattern of a shielded SiP, and thus has a great impact on the SE, especially when the frequency is above 1 GHz. However, a good correlation is found between the SE based on average near-field and the SE derived from the radiated power. This study has revealed the near-field shielding properties of SiP, which is helpful for building and analyzing the correlation among the SEs measured by different methods, including the near-field scanning, transverse electromagnetic (TEM) cell and reverberation chamber.

Analysis of shielding effectiveness by optimizing aperture dimensions of a rectangular enclosure with genetic algorithm

Electromagnetic compatibility (EMC) has now become a substantial challenge more than any other time sincethe number of electric vehicles (EV) increased rapidly. The electric driving system in an EV consists of power electroniccomponents supplied by high voltage battery source. They are both source and victim of potential electromagneticinterference (EMI) since fast switching process occurs inside them. Electromagnetic shielding provides a significantprotection against EMI for any electrical and electronic components inside the vehicle. In this paper, analysis of shieldingeffectiveness (SE) by optimizing aperture dimensions of a rectangular enclosure is investigated. Realistic dimensions of theshielding enclosure of an inverter component are employed. An optimization methodology based on genetic algorithm(GA) is carried out and applied to an SE analytical model. It is aimed to keep the total aperture area as large aspossible inside a particular dimension range while improving SE of the enclosure compared with the reference level.Obtained optimization results are presented by indicating optimum aperture length and width which satisfy both EMCand dimension requirements. Finally, it is concluded that through the optimization methodology designed in this study,the SE of the enclosure is raised from a poor level to an average one while providing larger aperture area.

차폐망 및 접지형태에 따른 고출력 전자기 펄스에 대한 차폐성능 분석

차폐망 및 접지형태에 따른 고출력 전자기 펄스에 대한 차폐성능 분석

Analysis and test of electromagnetic shielding effectiveness of optical window

Analysis and test of electromagnetic shielding effectiveness of optical window

Shielding Effectiveness Analysis of the Conducting Spherical Shell With a Circular Aperture Against Low Frequency Magnetic Fields

In this paper, an analytical model is presented to calculate the low frequency magnetic shielding effective (SE) of the spherical shell with a circular aperture and finite conductivity. This model is obtained by the combination of two submodels: the finite conductivity shell without the aperture, and the perfect conductor shell with the aperture. Both the submodels have existing analytical solutions. The first submodel represents the diffusion effect of magnetic field penetration through the conducting shell, and the second one denotes the aperture effect of magnetic field leakage through the aperture. The total magnetic field is the superposition of these from the two submodels. Calculation results are provided for an aluminum spherical shell of radius 0.1m for frequencies between 10Hz and 1MHz. The results are in good agreement with these form 2D axisymmetric finite element simulations. It is shown that there is a critical frequency. Below this frequency, the diffusion effect is dominant and the SE enhances with the increase of frequency. Above this frequency, the aperture effect is dominant and the SE keeps unchanged with the variation of frequency. In addition, the phase shift characteristics are also analyzed for the two effects respectively, and are employed to elucidate the mechanism of the resonance phenomenon of the SE around the critical frequency. Further, the effect of aperture depth is investigated numerically, which shows that increasing the depth has similar effect on SE like reducing aperture radius.

Shielding effectiveness analysis of a rectangular enclosure with wire mesh covering

Analytical model has been developed for the shielding effectiveness of a rectangular enclosure with wire mesh covering. The aperture covered by wire mesh is replaced by an equivalent impedance which contains the surface resistance of the wire mesh. Based on the transmission line theory, the enclosure is modelled as a length of rectangular waveguide ended with a short circuit, then the shielding effectiveness (SE) of the enclosure can be calculated. By comparing the calculation with the full-wave simulation software, the proposed method is validated.

Simulation and experimentation of wide frequency electromagnetic shielding coating used for carbon fiber composite materials of track vehicles

Computer Simulation Technology EM and Computer Simulation Technology Microwave Studio electromagnetic simulation software were used to simulate the carbon fiber composite materials with a new type of wide frequency electromagnetic shielding coating. DC magnetic field, low-frequency electromagnetic fields, and mid-high frequency electromagnetic shielding effectiveness analysis model were established in order to study the influence of permeability, conductivity, coating thickness and other parameters in the typical frequency range research on the shielding effectiveness. The results show that the composite coating material with reasonable design can effectively enhance the electromagnetic shielding performance of carbon fiber composite materials in the DC [Formula: see text]18 GHz frequency range.

Series Impedance and Losses of Magnetic Field Mitigation Plates for Underground Power Cables

This paper deals with magnetic field mitigation techniques for underground power systems by using conductive or ferromagnetic shielding plates. Two new aspects are considered in this paper beside the shielding effectiveness analysis: the contribution to the series impedance and power losses due to the conducting set formed by the shielding plate/earth return path. A finite thickness ferromagnetic or conductive shielding is assumed buried parallel to the soil/air plane surface in order to model the induction magnetic field mitigation of a power underground cable system in flat configuration. An analytical method, appropriate to deal with possible optimization procedures, is used based on the magnetic vector potential for multilayered configurations where the shielding plate is treated as a different layer. Results for the magnetic field reduction factor at the soil surface are obtained for different shielding materials, different shielding thickness values, as well as different frequency values. Results are validated by employing the finite element analysis.

Modified Shielding Effectiveness Equation for Novel Multilayered Waveguide-Below-Cutoff Array

This paper presents an airflow analysis and a shielding effectiveness (SE) analysis for a multilayered waveguide-below-cutoff array (WBCA) used to prevent electromagnetic penetration. The performance of the conventional unit square WBCA and the multilayered WBCA is compared. For the airflow analysis, the simulations are performed at the entrance and exit of the shielding structure when an airflow velocity of 1 m/s is injected at the inlet. The velocity loss and pressure difference of the multilayered WBCA are improved compared with the unit square WBCA. In terms of the shielding, the SE of the multilayered WBCA is compensated by increasing the number of overlapping layers. Furthermore, a new SE equation is derived by modifying that of the unit square WBCA.

Shielding Effectiveness Analysis and Modification of the Coupling Effect Transmission Line Method on Cavities with Multi-Sided Apertures

Because the traditional transmission line method treats electromagnetic waves as excitation sources and the cavity as a rectangular waveguide whose terminal is shorted, the transmission line method can only calculate shielding effectiveness in the center line of the cavity with apertures on one side. In this paper, the aperture coupling effect of different sides was analyzed based on vector analysis. According to the field intensity distribution of different transport modes in the rectangular waveguide, the calculation model of cavity shielding effectiveness in any position is proposed, which can solve the question of the calculation model of shielding effectiveness in any position in the traditional method of equivalent transmission methods. Further expansion of the equivalent transmission lines model is adopted to study the shielding effectiveness of different aperture cavities, and the coupling effect rule of the incident angle, the number of apertures, and the size of the cavity is obtained, which can provide the technical support for the design of electromagnetic shielding cavities for electronic equipment.

Electromagnetic Compatibility Issues in Electric Vehicle Applications

The paper develops analyses electromagnetic compatibility issues in electric vehicles. Particular techniques are developed involving special elements of tubular geometry based on the analytical solution of diffusion equation combined with standard finite elements, for analysis of electromagnetic shielding effectiveness in power cables due to power static converter operation. Particular simulations analyze the exposure levels due to variable frequency magnetic field on anatomically detailed human models in electric vehicle cabin environment. The results obtained have been compared to those found in the literature and to measured ones.

Dimension-Reduced Sparse Grid Strategy for a Stochastic Collocation Method in EMC Software

Stochastic collocation method (SCM), a prevailing uncertainty analysis method, has been successfully implemented in electromagnetic compatibility (EMC) simulation, especially in EMC commercial software. However, the “curse of dimensionality” problem (dimensionality means the number of uncertain variables) limits the application of the SCM. This paper proposes a novel sparse grid strategy in order to improve the computational efficiency of the SCM, especially in high-dimensionality case. In the proposed strategy, it is revealed that the number of the collocation points is in proportion to the dimensionality. By simulating two shielding effectiveness analysis examples in CST software, the feasibility of the proposed method can be presented clearly, with the help of the feature selective validation method.

Study on textile comfort properties of polypropylene blended stainless steel woven fabric for the application of electromagnetic shielding effectiveness

In this study, the different proportion of conductive component blended with polypropylene yarn were taken for making conductive textile samples for analysis of electromagnetic shielding effectiveness, fabric bending moment and air permeability. The ASTM D4935 coaxial transmission line method was used to study the electromagnetic shielding. Electromagnetic shielding effectiveness of textile structures containing different percentage of metal content ranges from 1 to 50 dB at high frequency range. Breathability of structures, more precisely air permeability was considered as one of important parameters for designing of electromagnetic radiation protective fabrics for certain applications. The bending moment of samples is decreases with increasing metal component percent.

Shielding Effectiveness Analysis of Large Enclosures by Domain Decomposition Mesh-Free Method

In this paper, an efficient domain decomposition mesh-free method (DD-MFM) is introduced to analyze the shielding effectiveness of a perforated metallic structure. First, a DD scheme is developed for a two-dimensional Fredholm integral equation of the second kind. Then, it is applied to a MFM-based method in a shielding enclosure problem. To this end, N number of nodes are considered on each aperture surface representing an individual domain. The MFM formulation through the DD scheme leads to M coupled equations, where M is the number of apertures (domains). In each equation, coefficient matrices have only 2 N × 2 N dimension, while the conventional MFM (C-MFM) would produce 2 MN × 2 MN coefficient matrices. Thus, DD-MFM technique will overcome the ill-conditioning problem of matrices and results in much more efficiency, especially for problems with large matrix condition number, albeit at the cost of generating M coupled equations. Coupled equations are treated in an iterative process. To show the efficiency and accuracy of the proposed method, several enclosures with different size and multiple apertures are studied. The results are validated with the C-MFM and two well-known commercial software, FEKO and Computer Simulation Technology. The important output of the proposed DD-MFM method is that it makes the analysis of large enclosure with numerous apertures efficiently possible.