Electromagnetic Field Shielding Research Articles

Dual-Functional Cross-Meandering Resonator for Power Frequency Electromagnetic Shielding and Wireless Sensing Communication.

The research on MEMS wireless sensing technology adapted to strong power frequency electromagnetic field environments is of great significance to our energy security, economic society, and even national security. Here, we propose a subwavelength cross-meandering resonator (0.49λ0 × 0.49λ0) to simultaneously achieve power frequency electromagnetic field shielding and wireless communication signal transmission. The element size of the resonator is only λ0/11, which is much smaller than that of previous works. In the resonator, a resonance mode with the significant near-field enhancement effect (about 180 times that at f = 1 GHz) is supported. Based on the self-made shielding box experimental setup, the measured shielding effectiveness of the resonator sample can reach more than 33 dB. Moreover, by integrating the cross-meandering resonator with the MEMS sensor, a wireless communication signal can be successfully transmitted. A dual-function cross-meandering resonator integrated with sensors may find potential applications in many military and civilian industries associated with strong power frequency electromagnetic fields.

Recycling Functional Fillers from Waste Tires for Tailored Polystyrene Composites: Mechanical, Fire Retarding, Electromagnetic Field Shielding, and Acoustic Insulation Properties-A Short Review.

Polymer waste is currently a big and challenging issue throughout the world. Waste tires represent an important source of polymer waste. Therefore, it is highly desirable to recycle functional fillers from waste tires to develop composite materials for advanced applications. The primary theme of this review involves an overview of developing polystyrene (PS) composites using materials from recycled tires as fillers; waste tire recycling in terms of ground tire rubbers, carbon black, and textile fibers; surface treatments of the fillers to optimize various composite properties; and the mechanical, fire retarding, acoustic, and electromagnetic field (EMI) shielding performances of PS composite materials. The development of composite materials from polystyrene and recycled waste tires provides a novel avenue to achieve reductions in carbon emission goals and closed-loop plastic recycling, which is of significance in the development of circular economics and an environmentally friendly society.

Corrosion and heat-resistant SiCN/C as lightweight fibers for microwave absorption and electromagnetic field shielding in Ku-band

SiCN fibers are usually combined with metals to increase the magnetic loss in electromagnetic field (EMF) shielding, but this results in high weight density, easy corrosion, difficult treatment, and high cost of the material. This study proposes the manufacturing of corrosion and heat-resistant ceramic lightweight fibers containing in-situ synthesized carbon nanostructures (SiCN/C) with excellent EMF shielding in Ku-band (12.4–18 GHz). The samples showed differential trends of EMF shielding effectiveness in terms of reflectance, transmittance, and absorption behavior. Compared to SiCN fibers, the EMF absorption was two times greater when carbon was added to the SiCN matrix. A minimum reflection coefficient (S11) of −12 dB was observed for SiCN/C fibers, meaning a high shielding efficiency with >90 % of the EMF energy shielded. On the other hand, SiCN fibers showed a minimum S11 of −7 dB, resulting in a protection of 80 % against EMF energy. Computational simulations clarified the better features of SiCN/C in electromagnetic shielding compared to SiCN, which was ascribed to enhanced conduction loss derived from conductive free carbon, and dipole and interfacial polarization loss generated by defects. The fibers were resistant to acidic and basic environments and oxidation of up to 600 °C. Moreover, the addition of carbon precursor represented a weight decrease of 17 % for SiCN/C compared to SiCN fibers. This research will afford an alternative solution for the manufacturing of SiCN/C fibers with EMF absorption properties that can be used as lightweight materials in harsh environments.

ELECTROMAGNETIC SHIELDING AS A WAY OF PROTECTING INFORMATION FROM ITS LEAKAGE BY TECHNICAL CHANNELS

In this paper, investigated one of the way of protecting information from its leakages through the technical channels, such as shielding. The first part of the work mainly consider the theoretical principles of shielding, such as definition and process of shielding, its types, main task of the shield, highlighted the concept of shielding efficiency, presented dependence for calculating the efficiency of electromagnetic shield, provided shields classification according to three characteristics: type of field interference, design and material, shield forms, for each of them presented dependence for calculating shielding efficiency of magnetic and electromagnetic field, presented dependence for calculating depth of penetration, as a value that characterizes shielding effect of shielding material. The second part of work consider separate types of shielding such as shielding of the electric field, dependence for calculating its effectiveness, presented main requirements for electric shields, considered the principles of shielding for low-frequency and high-frequency magnetic fields, dependences for calculating its shielding efficiency, presented main requirements for magnetostatic shields, considered shielding of electromagnetic fields, provided main mechanisms of protection against electromagnetic interference, presented dependence for calculating shielding efficiency of electromagnetic field. In the third part of the work calculated shielding efficiency and penetration depth of electromagnetic field for magnetic and non-magnetic materials at given frequencies with different conductivity and different thickness of shield walls, provided graphs of frequency dependence of shielding efficiency at different thickness of the shield walls, shown graph of frequency dependence of penetration depth for different materials, made conclusions and provided recommendations regarding selection of shielding materials at high and low frequencies, presented shielding materials for permanent magnetic field and high-frequency electromagnetic field.

Development of materials with a multilayer structure of the gradient type based on liquid compositions for the shielding of electromagnetic fields

Nowadays, for shielding and absorption of electromagnetic fields of a wide frequency range, composite materials or solid metal structures are offered and widely used. The article deals with research and development of multilayer protective liquid materials for shielding electric, magnetic and electromagnetic fields of a wide frequency range. A series of liquid shielding mixtures based on standard certified paints and finely dispersed magnetite was produced. Testing of the protective properties of these mixtures was carried out by sequentially applying 2–3 layers of mixtures to the surface, each of which had a certain concentration of the shielding substance. The shielding and reflection coefficients for these multilayer structures are given. It is shown that the advantage of the developed multilayer protective liquid materials lies in obtaining a gradient of electrophysical and magnetic properties of the protective structure with the possibility of calculating dielectric and magnetic permeabilities, taking into account the morphology of the shielding particles. A method of obtaining protective materials of the gradient type, which reduce the influence of electromagnetic fields, is proposed, which is possible for the treatment of surfaces of large areas and complex configurations.

Some aspects of electromagnetic field shielding

Some aspects of electromagnetic field shielding

The application of composites based on recycled materials for electromagnetic field shielding

Wydawnictwo SIGMA-NOT wydaje czasopisma fachowe informujące swoich czytelników o najnowszych osiągnięciach naukowych i nowoczesnych rozwiązaniach technicznych w Polsce i na świecie, popularyzuje problemy techniczne oraz poszerza wiedzę i kulturę techniczną.

A Study on the Possibility of Using Iron Scale in the Construction of Electromagnetic Field Shields

Electromagnetic radiation can have a negative effect on electronic circuits, for example, by disrupting their work and communication. Therefore, there is a need to reduce or eliminate electromagnetic interference using shields. This paper focuses on using waste materials in the form of iron scale, which is easy and inexpensive to obtain for shielding. Iron scale is the result of gaseous or aqueous corrosion, due to which a superficial layer of metal oxides formed on the surface of heated metal objects as a result of their contact with air or water during an industrial process is developed. In this study, morphology, chemical, and phase composition measurements were carried out. The results show that all the iron-based materials investigated are mainly composed of iron oxides and pure iron. The polymer–iron composites with different quantitative and qualitative compositions were prepared to verify the shielding effectiveness. The electrical resistance, impact strength, and magnetic properties were measured, and dynamic mechanical thermal analysis and tensile strength tests were performed. The tests confirmed the suitability of iron scale for the construction of electromagnetic field shielding material. Iron scale is cheap and easy to obtain from iron-based waste materials. The developed composites are easy to form and use recycled material.

Simulations and tests of the effectiveness of electromagnetic field shielding by shields made of recycled materials

Wydawnictwo SIGMA-NOT wydaje czasopisma fachowe informujące swoich czytelników o najnowszych osiągnięciach naukowych i nowoczesnych rozwiązaniach technicznych w Polsce i na świecie, popularyzuje problemy techniczne oraz poszerza wiedzę i kulturę techniczną.

Electromagnetic Field Analysis and Shielding Method of Underground Variable Frequency Power Cable

The transmission and radiation of underground variable frequency electromagnetic waves will seriously interfere with the operation of the power cable and its surrounding environment. At present, the test methods for power cables basically require the impedance of the test system to match the characteristic impedance of the cable. The defect is that the process of designing and making the impedance matching impedance network is relatively complex and requires high manufacturing accuracy. In order to solve these problems, this paper puts forward the electromagnetic field fast detection formula and electromagnetic field shielding method of underground variable frequency power cable. The research method of this paper is the principle of shielding electromagnetic field materials and the suppression principle of shielding layer for electromagnetic coupling. The function of the two principles is to study the reflection, absorption, and multiple reflection of electromagnetic waves and to study the cut-off frequency of the nonmagnetic shielding layer. These two principles guide the experiment. In this paper, the measurement formula of the shielding performance of mismatched cables is derived through experiments. The results show that the error of the measurement formula is no more than 8 dB. Then, through the experiment of restraining the interference of magnetic materials on the electromagnetic field, it is concluded that the magnetic field shielding performance can reach 20 dB. Then, through the performance test of electromagnetic field shielding materials, the shielding efficiency of metal fiber antiradiation materials is the largest, and the average efficiency reaches 76.4 dB.

Design of Compact Magnetic Coupler With Low Leakage EMF for AGV Wireless Power Transfer System

Severe leakage electromagnetic field (EMF) generated by automatic guided vehicle wireless power transfer (WPT) systems is hazardous to the surrounding objects. To reduce the leakage EMF, a novel compact magnetic coupler is proposed in this article. The idea of this work is, first, adopting the compensation inductors of the <i>LCC</i>&#x2013;<i>LCC</i> compensated WPT system as EMF canceling coils, and EMF alleviation can be achieved without any additional components; second, integrating the power transfer coils and the EMF canceling coil into one magnetic coupler to compact the system. An experimental prototype is fabricated to verify the EMF shielding effect of the proposed magnetic coupler. Experimental results show that compared with that of the general magnetic coupler, the EMF of the proposed magnetic coupler is dramatically reduced by 82.24&#x0025; at maximum and by 75.18&#x0025; on average from <i>y</i> &#x003D; 200 to 350&#x00A0;mm. Besides, the transfer efficiency is decreased by 0.32&#x0025; with the same output power. That means the proposed magnetic coupler can effectively alleviate the EMF without a significant negative impact on the transfer efficiency.

The research and the analysis of electromagnetic field shielding properties of the textile materials with an electroconductive coating

Wydawnictwo SIGMA-NOT wydaje czasopisma fachowe informujące swoich czytelników o najnowszych osiągnięciach naukowych i nowoczesnych rozwiązaniach technicznych w Polsce i na świecie, popularyzuje problemy techniczne oraz poszerza wiedzę i kulturę techniczną.

EMI Shielding and Absorption of Electroconductive Textiles with PANI and PPy Conductive Polymers and Numerical Model Approach

The paper presents the results and analysis of interdisciplinary research concerning electromagnetic field shielding, conductive polymers printed on textiles and numerical simulation using the finite element method (FEM). The use of conductive, layered textiles for shielding electromagnetic interference (EMI) has been proposed. After establishing the optimal conditions for deposition of polyaniline (PANI) and polypyrrole (PPy) on polyacrylonitrile (PAN) fabric, conductive composites were made by means of reactive inkjet printing. For this purpose, polyacrylonitrile (PAN) fabrics were coated with polyaniline or polypyrrole, obtained by chemical oxidation of aniline hydrochloride and pyrrole by ammonium peroxydisulfate. The morphology of the obtained coatings was observed using a scanning electron microscope (SEM). The conductive properties (surface resistance) of the fabrics were measured using the four-wire method, and the tests of the effectiveness of electromagnetic shielding were carried out using the waveguide method in the frequency range from 2.5 to 18 GHz. The results of experimental shielding effectiveness (SE) tests and numerical simulation showed that the composites of polyacrylonitrile with polyaniline PAN/PANI and polyacrylonitrile with polypyrrole PAN/PPy achieved very good and good EMI shielding efficiency, respectively. Moreover, the obtained measurement results were verified by numerical modeling with the use of FEM–ANSYS HFFS software.

Electromagnetic Field Shielding in Incubators

Purpose: Cell experiments are vitally dependent on CO2 incubators. The heating system of usual incubators result in undesirable induction of Electromagnetic (EM) fields on cells that result in decreased accuracy in bio-electromagnetic tests. EM shields can cause a considerable decrease in the stray fields and eliminate the undesirable induction. Materials and Methods: CST-2019 is used for simulations. five different shielding systems have been examined in this paper. We try to modify shape and material used for shielding to achieve better result. (Iron, Mu-Metal, steel). Results: We introduce a simple practical design, together with variations of previously reported ones, and numerical evaluation of their magnetic field attenuation. Conclusion: The targeted design decreases the field within the shield to about 0.03 times of the incident magnetic field, while having holes for air and CO2 exchange.

Effects of Electromagnetic Fields and their Shielding on the Growth of Dwarf Runner Beans

Abstract The aim of the study was to determine the effect of electromagnetic fields and their shielding on the growth of dwarf runner bean Phaseolus coccineus L. Three sectors were separated on the device emitting electromagnetic fields: “E” - sector emitting electromagnetic radiation with the predominance of the electrical component, “EM” - sector emitting electromagnetic radiation without domination of its components and “M” - sector with a predominance of magnetic component. Fields generated by the device were also shielded with ADR TEX, a screen based on a nanocomposite in which the electric component of the electromagnetic radiation is absorbed by water dispersed within a dielectric matrix in various ways. The composites exhibit high dielectric absorption and shield electric fields within the frequency range from ~100 mHz to ~100 kHz. Electromagnetic fields with the predominance of the electrical component and without domination of its components delayed the initial emergence of runner bean seedlings. Shielding of electromagnetic field without domination of its components with ADR TEX screen protected against this negative impact on the emergence rate of young runner bean seedlings. Exposure of plants to differentiated electromagnetic fields adversely affected their growth. Plants exposed to electromagnetic radiation without domination of its components had the lowest height and the shortest internodes. Shielding of electromagnetic fields with ADR TEX screen efficiently protected against their negative impact on the plant growth. Electromagnetic fields and their shielding did not influence the size of leaves and the index leaf greenness (SPAD).

The composite facing material for electromagnetic felds shielding

The facing material was developed for the purpose of shielding man-made electromagnetic fields in production working and domestic conditions. The facing material was designed on the base of latex and fine iron ore concentrate as filler. The experimental data on shielding of electromagnetic fields of ultrahigh frequencies and magnetic field of industrial frequency were obtained for different material thicknesses and concentration of screening particles. The significant increase of the shielding coefficients was established and explained by the manifestation of the percolation effect - the increase of the material conductivity at the critical concentration of the conductive component. The calculation apparatus for determining the dependence on the shielding properties of the material on the concentration of shielding substance was proposed. The method of the screening substance critical concentration calculation is shown to enable designing materials of lower thickness, weight and self-cost.

Effects of Electromagnetic Fields and their Shielding on the Quality of Carrot (Daucus Carota L.) Seeds

Abstract The aim of the study was to determine the effect of electromagnetic fields and their shielding on carrot seed quality. Three sectors were separated on the device emitting electromagnetic fields: “E” - sector emitting electromagnetic radiation with the predominance of the electrical component, “EM” - sector emitting electromagnetic radiation without domination of its components and “M” - sector with a predominance of magnetic component. Fields generated by the device were also shielded with ADR TEX screen, based on a nanocomposite in which the electric component of the electromagnetic radiation is absorbed by water dispersed in a dielectric matrix in various ways. The composites exhibit high dielectric absorption and shield electric fields within the frequency range from ~100 mHz to ~100 kHz. Seed germination and vigour were evaluated at 20 °C in darkness. Mycological analysis was performed using a deep-freeze blotter test. Exposure of seeds to radiation with the predominance of the electrical component and electromagnetic radiation without domination of its components combined with shielding of electromagnetic fields with ADR TEX (E+ADR TEX and EM+ADR TEX) increased seed germination energy and germination capacity compared to these treatments without shielding and control. The percentage of abnormal diseased seedlings in treatments with shielding of electromagnetic fields with ADR TEX (E+ADR TEX, EM+ADR TEX and M+ADR TEX) was significantly lower than in the treatments without shielding and in control. None of the treatments affected seed vigour. Generally, exposure of seeds to electromagnetic radiation did not influence the incidence of fungi.

Compromise between magnetic shielding and mechanical strength of thin Al/Steel/Al sandwiches produced by cold roll bonding: Experimental and numerical approaches

Electromagnetic pollution become an issue these last years with growth of electrical and electronic industry. The shielding of electromagnetic fields is one solution to reduce effects of this pollution. This study proposes an Al/Steel/Al sandwich produced by cold roll bonding to shield low frequency magnetic wave in near field. The structure evolution of sandwich composite has been characterized in function of the reduction rate of thickness. The bonding quality of Al/Steel interfaces has been then quantified by Tensile Bond Strength Test. Finally, the magnetic shielding effectiveness of the composite and the initial Al and steel sheets have been evaluated experimentally and numerically. During cold roll bonding, plastic instability has been observed and causes steel necking and fragmentation. A numerical model has been developed to explain its origin. A good bond quality is attained when debonding of Al/Steel interfaces requires the deterioration of the composite. The composite takes both shielding behavior of steel and Al and can shield low frequency. However, steel fragmentation has a negative impact on shielding effectiveness. The optimal condition between shielding and mechanical properties is then obtained for a reduction rate of 62% where only few fragmentations are observed.

Shielding a high-sensitivity digital detector from electromagnetic interference.

PurposeTo document a study in shielding a high‐sensitivity digital mammography system detector from AC magnetic fields of magnitudes great enough to induce imaging artifacts.Methods/materialsPreliminary evaluation of AC magnetic fields at a site designated for a digital breast tomosynthesis (DBT) system raised concerns that the magnetic component of electromagnetic interference (EMI) may be great enough to induce imaging artifacts. Subsequent measurements using digital detector arrays from two separate manufacturers verified this concern, and AC magnetic fields were mapped, spatially and temporally, throughout the area of concern. A simple shielding model was developed to elucidate the physics of extremely low‐frequency (ELF) EMI shielding and independently verify a commercial group's proposed shielding design and installation. Postshielding measurements were performed to demonstrate that the EMI fields were reduced to acceptable levels.ResultsPreshielding measurements showed AC magnetic fields significantly exceeding manufacturers’ tolerances for artifact‐free imaging in DBT. Continuous measurements demonstrated that the EMI fields varied significantly over time. Some locations in the room routinely averaged above 30 mG and occasionally exceeded 100 mG. The source was attributed to an adjacent electrical supply room, and temporal changes of the EMI were attributed to variations of the building electrical loads. The proposed shielding primarily consisted of continuous aluminum (6.35 mm thickness) and was installed by a group specializing in electromagnetic field shielding. Postshielding measurements demonstrated that the EMI fields were significantly reduced, generally to less than 0.5 mG, and that the shielding effectively dampened the large variations due to dynamic building electrical loads. Subsequent installation and evaluation of a DBT system revealed no issues with imaging artifacts.ConclusionsThe successful shielding of ELF EMI involves physical principles that are not commonly encountered by medical physicists. Modern high‐sensitivity digital detectors may be successfully shielded against imaging artifacts with careful application of these principles.

Prevention of concrete structures from collapsing

At the end of the 20th century requirements on using electrical properties of building materials emerged for application in heating of trafficable surfaces, grounding of electrostatic charges in floors, shielding of electro-magnetic fields and diagnosis of concrete structure state in the course of time. For this reason, it was necessary to design special fibre-cement elements able to transfer any mechanical impulse to an electricallymeasured signal detected as a change in electrical resistance with computer outputs. Regarding previous research studies, it was concluded that special fibre-cement composites are able to conduct electric current under specific conditions. This property is ensured by using of various kinds of carbon materials. Though carbon fibres are less conductive than metal fibres, composites with carbon fibres were evaluated as better current conductors than the composites with metal fibres. By means of various kinds of carbon particles and fibres it is possible to design cement composites with an ability to monitor changes in electrical conductivity of concretes. The designed composites are assembled with conductive wires and connected with a special electronic equipment for monitoring of changes in alternate voltage passing through the tensometer within mechanical loading of a concrete element in which the composite is integrated. The tensometers are placed preferably into parts of the concrete elements subjected to compression, such as simple reinforced columns or upper parts of longitudinal beams. Several tests of repeated loading and simultaneous monitoring of vertical as well as horizontal prefabricated concrete elements were carried out and evaluated.