Effects Of Electromagnetic Interference Research Articles

Enhancing the electromagnetic interference shielding effectiveness of carbon-fiber reinforced cement paste by coating the carbon fiber with nickel

The effectiveness of electromagnetic interference (EMI) shielding is valuable for construction materials and can be enhanced by the addition of carbon fiber to cement. This work reports for the first time that nickel coating on carbon fiber enhances the shielding effectiveness (200–2000 MHz, radio wave) of carbon-fiber cement by increasing the absorption loss SEA, due to the increase in electrical conductivity and magnetic permeability. The SEA/thickness enhancement by the coating decreases with increasing fiber content, because the fiber content increase enhances the conductivity, thereby promoting SEA and diminishing the magnetic influence of the nickel. The SEA/SET (SET = total loss) tends to be higher with the coating. The reflection loss SER is not affected by the coating, because the coating increases both conductivity and permeability, which affect SER oppositely, and the skin depth is smaller for nickel than carbon. The SEA/thickness and SER increase with increasing fiber content, which promotes the conductivity. The trend is less clear with the coating, due to the coating affecting both conductivity and permeability. The SEA/thickness tends to increase with increasing frequency, whereas SER trends oppositely.

Tailoring hierarchical carbon nanotube cellular structure for electromagnetic interference shielding in extreme conditions

Stable and resilient materials are in great demand for electromagnetic interference (EMI) shielding applications under extreme conditions. Here we present a facile method that could tailor and strengthen the pore structure of carbon nanotube (CNT) foams to obtain highly effective and reliable EMI absorbers that maintain their superior EMI effectiveness under heavy mechanical deformation and extremely high temperature. The hierarchical macro-to-micro pore structure and properties of CNT foam were tailored in a wide range via a secondary chemical vapor deposition (CVD) process. Benefiting from the multi-level reflection in hierarchical pore structures, the optimized CNT foam presents a high shielding efficiency (SE) of 84 dB and a specific SE (SSE/t) of 5.6 × 104 dB·cm2·g-1 in X-band. The tailoring process also provides outstanding stability and mechanical resilience, leading to 83.8% EMI SE maintained after 1000 compressive cycles. Moreover, the foams can keep 76.5% EMI SE after 30 min of 1000°C thermal-destruction process (in argon atmosphere). All these features demonstrate the potential of using the optimized CNT foam as an EMI shielding material under extreme conditions. These findings have essential inspiration for pore engineering in CNT-based EMI shielding materials, giving further guidance for the design of EMI shielding materials used in harsh conditions.

Flexible, Ultralight, and Mechanically Robust Waterborne Polyurethane/Ti3C2Tx MXene/Nickel Ferrite Hybrid Aerogels for High-Performance Electromagnetic Interference Shielding.

Flexible, ultralight, and mechanically robust electromagnetic interference (EMI) shielding materials are urgently demanded to manage the increasing electromagnetic radiation pollution, but it remains a great challenge to simultaneously achieve ultralight yet mechanically robust properties while retaining high-efficiency EMI shielding performance. Herein, we fabricate a novel waterborne polyurethane/Ti3C2Tx MXene/nickel ferrite (WPU/MXene/NiFe2O4) hybrid aerogel by constructing a strong chemical bonding interaction between an NCO-terminated WPU prepolymer and hydroxyl functionalized MXene nanosheets. The resultant aerogels exhibit remarkable lightweight and mechanical properties, particularly high compressive stress far exceeding that of other MXene-based and WPU-based porous materials. Furthermore, synergistic effects of the oriented porous architecture and the multiphase skeleton endow the hybrid aerogels with a high X-band EMI shielding effectiveness (SE) of 64.7 dB at a low density of ∼38.2 mg/cm3. The corresponding specific SE value achieves 1694-3124 dB·cm3/g, and the SSE/d is up to 15,620 dB·cm2/g, surpassing that of most reported EMI shielding materials. Importantly, this aerogel, with excellent electromagnetic radiation protection effects and shielding reliability, is highly promising for long-term and effective EMI shielding service in various application environments.

3D printing of PDC-SiOC@SiC twins with high permittivity and electromagnetic interference shielding effectiveness

Effective electromagnetic interference (EMI) shielding requires materials with high permittivity. The current study reports 3D printed polymer-derived SiOC ceramics (PDC) modified with SiC nanowires (SiCnw) exhibiting both high real and imaginary parts of permittivity within X-band. SEM results indicated that a large number of pores and cracks exist in the SiOC, and twinned SiCnw were uniformly grown among them along with the existence of graphite microcrystals when the sintering temperature was 1500 ℃. The real part of permittivity ranged from 16.6 to 28.9 while the imaginary part from 31.7 to 34.2 in X-band. The EMI total shielding effectiveness (SET) of the ceramics could reach 34.7 dB with absorption loss (SEA) of 29.3 dB and reflection loss (SER) of 5.4 dB. Meanwhile, the 3D printed PDC-SiOC ceramics at 900 ℃ sintering temperature possess certain mechanical properties with the magnitude of compressive strength being 12.57 MPa.

Effects of Platform EMI in Synchronized Cooperative Broadcast Systems

On military platforms, several communication systems are colocated with electronic systems. The resulting electromagnetic environment can degrade communication performance. This is particularly evident in vehicles and other small platforms, where a lot of equipment is installed in a small space. A consequence of high electromagnetic interference (EMI) levels is a reduced communication range for radio systems. The focus of this article is to analyze how a complex interference situation affects frequency-hopping ad hoc networks using synchronized cooperative broadcast (SCB). SCB is a communication technique used by modern tactical wideband radios and a form of cooperative relaying. The interference environment, both background environment and platform interference, is viewed in terms of an increasing equivalent noise figure of the radio receiver. Additionally, there is interference from colocated radio systems yielding internetwork interference. The impact on SCB network performance from these interference sources is analyzed. The results show that SCB is robust toward interference in terms of a maintained high delivery ratio. However, in situations with low network diversity, EMI problems on some platforms can affect the whole network performance.

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.

Facile construction of 2D MXene (Ti3C2Tx) based aerogels with effective fire-resistance and electromagnetic interference shielding performance

• Preparation of non-toxic, lightweight and fire-resistant EMI shielding aerogel. • Such aerogels are fabricated by freeze-drying method. • High SSE/t value (5729 dB cm 2 g −1 ) exceeds many other reported porous materials. Rapid growing of electronics has not only caused severe electromagnetic wave pollution, but also created a risk of fire and explosion. Therefore, developing ultralight, fire-resistant, high-performance electromagnetic interference (EMI) shielding materials are imperative but also challenging. Considering the outstanding metallic conductivity and high aspect ratio, 2D Ti 3 C 2 T x has been reported to be one of the most promising candidates for exhibiting excellent EMI shielding performance. Herein, we demonstrate a facile method to fabricate cellulose nanofiber (CNF)/ammonium polyphosphate (APP)/Ti 3 C 2 T x composite aerogels via a simple freeze-drying method. The resultant CNF/APP/Ti 3 C 2 T x composite aerogels exhibited excellent fire-resistance without obvious shrinkage when placed over the flame of an alcohol burner. Besides, the 8-mm-thick composite aerogel with 60% of Ti 3 C 2 T x showed an average EMI shielding effectiveness of 55 dB (specific EMI shielding effectiveness/thickness could be ~5729 dB cm 2 g −1 ) with an absorption-dominant mechanism. This performance is owing to the relative high electrical conductivity (12 S/m) and multiple reflections from the porous structure. These characteristics make the composite aerogel a much more competitive product for a high-performance EMI shielding material.

Possibilities and safety of physiotherapy in patients with implanted cardiac devices

Widespread implantation of cardiac devices, i.e. cardiac pacemakers, cardioverter-defibrillators and cardiac resynchronisation devices improved patients survival. It has resulted in increase in number of ageing patients with cardiac devices who need physiotherapeutic treatment due to accompanied comorbidities. Hence the study of the interaction between functions of cardiac devices and physiotherapeutic treatment techniques is particularly relevant. The use and safety of physiotherapeutic treatment techniques producing electromagnetic field which in turn eventually cause harm of the cardiac devices are being discussed in present review article. The possible adverse effects of such interaction are abrupt failure to stimulate or triggering of shock therapy with consequent arrhythmic events including cardiac arrest. The technical characteristics particularly associated with electromagnetic interference are discussed here in detail. The attention is also payed to analysis of possible causes and effects of electromagnetic interference and safety measures as well.

Electromagnetic shielding behavior of epoxy multi‐hybrid composites comprises of E‐glass fiber, Ag nanoparticle, and Ni nanosheet: A novel approach

AbstractHigh performance epoxy based EMI shielding hybrid composites were prepared and characterized for their mechanical, magnetic, and Electromagnetic Interference (EMI) shielding behavior. The aim of this research was to enhance the electromagnetic interference shielding effect of a nanocomposite at high frequency with good mechanical strength. The shielding effectiveness of the epoxy composite was improved via the addition of E‐glass/silver nanoparticle and nickel nanosheets. The reinforcements were silane surface modified to enhance the adhesion and dispersion of reinforcements with matrix. The composites were prepared via hand layup process using glass fiber, silver nanoparticle, and Ni nanosheets followed by room temperature curing. The characterization of hybrid composites was done in accordance with ASTM standards. The results revealed that the Ag and Ni along with E‐glass fiber improved conductivity, permittivity, and permeability of epoxy composite. Similarly, the mechanical behavior of nanocomposite was found to be increased for tensile, flexural, and Izod impact toughness. Moreover, a maximum wave attenuation of –48 dB was observed for 3‐mm thick composite shielding material in “J” band frequency. These mechanically sound high EMI shielding lightweight polymer composites could be used as potential material for aerospace, defense, tele‐communication, and satellite data transfer applications. Besides the reduction of EMI effect between electronic gadgets could improves the utility and life span of electromagnetic devices and gadgets in several engineering applications.

Mechanism and protection on the data link of UAV exposed to electromagnetic interference

To solve the problem that the data link of the unmanned aerial vehicle (UAV) is vulnerable to electromagnetic interference during the flight and cause the link interruption, we took a certain data link of UAV as our research object, and proposed an experimental method of injection effect based on front door coupling. On this basis, we developed the effect experiment for the data link of UAV. We derived the sensitivity threshold curve of the data link and determined the sensitivity threshold, analyzed the work principle of RF front end circuit of the data link and the signal transmission process of the receiver under the effect of electromagnetic interference, revealed the mechanism of combined frequency interference and out of band saturation interference on data link, and finally carried out the experimental verification. Based on the test results, we put forward the corresponding protective methods from the aspects of the circuits level and adaptive control respectively.

WITHDRAWN: Shielding performance analysis of flexible multi-layered textile sheets based on polymer substrate

Abstract The need for effective Electro Magnetic Interference (EMI) Shielding became inevitable due to the rise of terahertz range technologies based electronic devices in civil, military and healthcare domains. In this paper we analyzed shielding performances of multilayered textile sheets with flexible polymeric substrate. The analysis considered factors like sensitivity of shielding effectiveness, conductivity of polymer inter-layers, thickness of textiles and frequency range. Many researchers contributed to the problem of EM shielding. The literature revealed that carbon based shielding is not mechanically flexible. Metal based shielding is heavy weight and not easy for tuning performance. Synthetic material with laminated sheets containing textile fabrics and conductive polymers was found a promising solution. Recently Aloia et al. explored shielding performances of flexible multilayer screens based on chemically doped graphene on polymer substrate. However, their research was not considering textiles. Textiles with polymer substrate will have impact in making EM shielding. Therefore further investigation is required to focus on textiles with conductive polymers in making EM shielding. This is the focus of the paper which analyzes various combinations and permutations of textile sheets and polymer substrate. Our mathematical and analytical results revealed that the proposed methodology can help improve decision making on EM shielding effectiveness significantly.

Electromagnetic Interference assessment of small electronic devices with a TEM cell

Electromagnetic Compatibility deserves an increasing interest because as modern industry 4.0 searches for better results in productivity and efficiency, it is expected the presence of an increasingly number of more complex electronic devices, including portable devices. This paper shows how a TEM cell allows analyzing the effects of Electromagnetic Interference, in an easy way and at small cost, during the development phase of the product.

In-situ reduction of silver by surface DBD plasma: a novel method for preparing highly effective electromagnetic interference shielding Ag/PET

Electromagnetic interference (EMI) shielding composites with good flexibility and weatherability properties have attracted increased attention. In this study, we combined the surface modification method of sub-atmospheric pressure glow discharge plasma with in situ atmospheric pressure surface dielectric barrier discharge plasma (APSDBD) reduction to prepare polyethylene terephthalate supported silver (Ag/PET). Due to the prominent surface modification of PET film, mild plasma reduction, and effective control of the silver morphology by polyvinylpyrrolidone (PVP), a 3.32 μm thick silver film with ultralow sliver loading (0.022 wt%) exhibited an EMI shielding efficiency (SE) of 39.45 dB at 0.01 GHz and 31.56 dB at 1.0 GHz (>30 dB in the range of 0.01–1.0 GHz). The SEM results and EMI shielding analysis indicated that the high performance originated from the synergistic effect of the formation of silver nanoparticles (AgNPs) with preferentially oriented cell-like surface morphologies and layer-by-layer-like superimposed microstructures inside, which demonstrated strong microwave reflection properties. Fourier transform infrared spectrometer and x-ray diffractometer showed that the surface structures of the heat-sensitive substrate materials were not destroyed by plasma. Additionally, APSDBD technology for preparing Ag/PET had no special requirements on the thickness, dielectric constant, and conductivity of the substrate, which provides an effective strategy for manufacturing metal or alloy films on surfaces of heat-sensitive materials at a relatively low cost.

Penetration through slots in cylindrical cavities with cavity modes overlapping with the first slot resonance

ABSTRACT We analyze the coupling into a slotted cylindrical cavity operating at fundamental cavity modal frequencies overlapping with the slot’s first resonance frequency through an unmatched formulation that accounts for the slot’s absorption and radiation processes. The model is validated through full-wave simulations and experimental data. We then couple the unmatched formulation to a perturbation theory model to investigate an absorber within the cavity to reduce the interior field strength, also validated with full-wave simulations and experiments. These models are pivotal to understanding the physical processes involved in the electromagnetic penetration through slots, and may constitute design tools to mitigate electromagnetic interference effects within cavities.

Effects of electromagnetic interference and crevice on corrosion of natural gas pipelines

Pipeline transportation is the main method of natural gas transportation. The intrinsic safety of natural gas pipelines has always been the focus of attention. During the transportation process, pipelines are affected by many factors. Existing studies have little research on the destruction of natural gas pipelines under the coupling of high-voltage transmission lines with electromagnetic interference and crevice corrosion. However, in actual inspections, it was found that this working condition caused very serious damage to the natural gas pipelines. Therefore, studying the corrosion law of natural gas pipelines under the coupling effect of electromagnetic interference and crevice corrosion can provide a theoretical basis for the safety management of natural gas pipelines. In this paper, through the electromagnetic interference simulation and corrosion test, the corrosion rate of natural gas pipelines under general corrosion, crevice corrosion and coupling of crevice corrosion and electromagnetic interference were analyzed.

EMI in a Cardiac Implantable Electronic Device (CIED) by the Wireless Powering of a Left Ventricular Assist Device (LVAD)

This article deals with the electromagnetic interference (EMI) in a cardiac implantable electronic device (e.g., implantable cardioverter-defibrillator or cardiac resynchronization therapy) generated by a left ventricular assisted device (LVAD) powered by a wireless power transfer (WPT) system. Wireless LVAD, not yet available in the market, is currently being investigated for many aspects spanning from electronics, hydraulic, electrical feeding, mechanical, and its possible impact on other implanted devices, such as a cardiac implantable electronic device (CIED). No results are yet published on possible EMI effects produced by the WPT coil currents in the pacing leads of a CIED implanted in the same patient with the LVAD. To this aim, the next generation of wireless LVADs with transcutaneous WPT system is first described, and, then, used to predict the induced voltage by the WPT system on a CIED lead. The obtained results demonstrate as the proposed WPT system, tested in accordance with the ISO 14117 standard, does not interfere with other CIEDs.

Hierarchical Porous Film with Layer-by-Layer Assembly of 2D Copper Nanosheets for Ultimate Electromagnetic Interference Shielding.

The emergence of technologies, such as 5G telecommunication, electric vehicles, and wearable electronics, has prompted demand for ultrahigh-performance and cost-effective shielding materials to protect against both the potentially harmful effects of electromagnetic interference (EMI) on human health and electronic device operation. Here, we report hierarchical porous Cu foils via an assembly of single-crystalline, nanometer-thick, and micrometer-long copper nanosheets and their use in EMI shielding. Layer-by-layer assembly of Cu nanosheets enabled the formation of a hierarchically structured porous Cu film with features such as multilayer stacking; two-dimensional networking; and a layered, sheetlike void architecture. The hierarchical-structured porous Cu foil exhibited outstanding EMI shielding performance compared to the same thickness of dense copper and other materials, exhibiting EMI shielding effectiveness (SE) values of 100 and 60.7 dB at thicknesses of 15 and 1.6 μm, respectively. In addition, the EMI SE of the hierarchical porous Cu film was maintained up to 18 months under ambient conditions at room temperature and showed negligible changes after thermal annealing at 200 °C for 1 h. These findings suggest that Cu nanosheets and their layer-by-layer assembly are one of the promising EMI shielding technologies for practical electronic applications.

EMI Analysis of Multiscale Transmission Line Network Using a Hybrid FDTD Method

A hybrid time-domain numerical method based on the full wave finite-difference time-domain (FDTD) method combined with a modified 1-D FDTD method has been proposed to analyze the electromagnetic interference (EMI) of multiscale transmission line networks in a metallic cabin in this article. This method is implemented through two numerical solvers for full wave and transmission line simulations, respectively, by adopting a set of reasonable physical boundary conditions between external fields and transmission line network. By using Ampere's law, the external fields can be transferred to a voltage source that can be further used as the forcing terms in the telegraph equation of the transmission line network. To overcome the challenge introduced by the multiscale size of the transmission line network, we combine 1-D explicit and implicit FDTD methods together to solve the coaxial cables and interconnects in PCB, respectively. Thus, among different subdomains, the hybrid method can be carried with the same time step without the restriction of the stability condition. Numerical examples show the accuracy as well as efficiency of the proposed method compared with the HSPICE and traditional FDTD method. In addition, the method is used successfully in analyzing the EMI effects of a complex transmission line network inside a cabin illuminated by external electromagnetic wave.

PVDF/CNF/IL composite film for shielding of microwave radiation

In this work materials have been used in the form of conducting polymer composite film for covering of different electrical and electronic equipment to provide effective electromagnetic interference (EMI) shielding. Pre localized CNF (CNF) powder will be mixed with Poly (vinylidene fluoride) (PVDF) and Ionic Liquid (IL) using solvent blending method to form a series of PVDF/CNF/IL composite films with different concentration of CNF and IL. Obtained composite films were characterized with Scanning Electron Microscopy (SEM) and Differential scanning calorimetry (DSC) for surface morphology and thermal analysis. Fabricated films were also examined for their mechanical properties. The dielectric properties of the film were measured with the help of impedance analyser. After this using dielectric properties of the films shielding effectiveness are calculated in the range of 100 KHz to 10 MHz. The fabricated film with composition of 60/10/30 exhibits the shielding effectiveness of 32 dB to 40 dB in entire frequency range and also has the elongation of 31%. The key advantage of obtained composite films is there light weight and flexibility can be used to shield small electronic equipment.

Magnetization and thickness dependent microwave attenuation behaviour of Ferrite-PANI composites and embedded composite-fabrics prepared by in situ polymerization

Ultrahigh efficient and effective electromagnetic-interference (EMI) shielding composites have been fabricated with the combination of Polyaniline and zinc-cobalt ferrites (Co1-xZnxFe2O4, 0.1 ≤ x ≤ 0.4). Ferrite nanoparticles synthesized via the sol-gel method were functionalized to polyaniline via in situ polymerization. Average crystallite sizes of the nanoparticles were estimated using Debye–Scherrer and Rietveld method and found to be in between 20-30 nm. FTIR spectra revealed the formation of interactions between the PANI molecules and the ferrite nanoparticles. Substitution of the nonmagnetic Zn ions considerably changes the magnetic properties of cobalt ferrites as observed from the M-H loops recorded by VSM at room temperature. The EMI-shielding performance of the fabricated composites was examined at various thicknesses with the polymer filler ratio of 1:1 in X-band frequency region using a vector network analyser. The EMI shielding performance of composites was found to be increasing with the thickness of composites where a thickness of 3.0 mm achieved an SE of ∼ 100 dB for the Co0.7Zn0.3Fe2O4-PANI composite. Composite absorbers were deposited on cotton fabrics for protective clothing by in situ incorporation during the synthesis of composites which displayed relatively high EMI shielding effectiveness (SE) (40-45 dB) at a thickness of only 0.30 mm for the fabrics. The PANI-Ferrite nanocomposites can be established as promising high capacity electromagnetic shielding materials because of the dipole polarization and the magnetic losses with low cost, lightweight, high durability and good flexibility.