scholarly journals Transmission Attenuation Power Ratio Analysis of Flexible Electromagnetic Absorber Sheets Combined with a Metal Layer

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1612 ◽  
Author(s):  
Jorge Victoria ◽  
Adrian Suarez ◽  
Jose Torres ◽  
Pedro Martinez ◽  
Antonio Alcarria ◽  
...  
Keyword(s):  
Electromagnetic Interference ◽  
Eddy Currents ◽  
Metal Layer ◽  
Measurement Procedure ◽  
Complex Permeability ◽  
Power Ratio ◽  
Electromagnetic Noise ◽  
Test Fixture ◽  
Novel Structure ◽  
Transmission Attenuation

Electromagnetic noise absorber sheets have become a solution for solving complex electromagnetic interference (EMI) problems due to their high magnetic losses. This contribution is focused on characterizing a novel structure that is based on an absorber film with a metal layer attached on its top side. Two different absorber compositions were combined with Al and Cu metal layers in order to study the improvement on the performance of these structures, depending on the complex permeability, absorber film thickness, and type of metal. The transmission attenuation power ratio of the absorber films is analyzed and compared to the performance of absorber and metal structures. The measurement procedure is carried out attaching the films into a microstrip line that has been designed based on IEC standard (IEC 62333-2). This test fixture is employed as a transmission line to simulate a general noise path. The performance of absorber composites to filter electromagnetic noise is evaluated through analyzing S21 and S11 parameters. This is carried out with the aim of finding out in which conditions the absorption loss is improved when a metal layer is attached. In addition, the possible re-radiation effect, due to the magnetic field that is generated by the eddy currents induced in the metal layer, is examined.

Novel Miniature DMFC With Monolithic Si Electrodes

2009 ◽  
Author(s):  
Masanori Hayase ◽  
Yosuke Saito
Keyword(s):  
Metal Layer ◽  
Catalyst Layer ◽  
Pt Catalyst ◽  
Galvanic Replacement ◽  
Porous Si ◽  
Si Substrate ◽  
Catalyst Layers ◽  
Novel Structure ◽  
Si Wafer ◽  
Immersion Plating

A through-chip porous Ru-Pt catalyst layer was fabricated on a Si wafer and a novel miniature DMFC (Direct Methanol Fuel Cell) was realized. Recently, we found that porous noble metal layer can be synthesized on Si substrate by immersion plating on a porous Si. In order to realize a DMFC with our novel structure, a porous Ru layer was synthesized on the Si substrate using the immersion plating on the porous Si, then Pt was deposited by galvanic replacement reaction on the porous Ru. The porous Ru-Pt structure showed catalytic activity on methanol oxidization. A through-chip porous Ru-Pt layer was fabricated on a Si wafer by plasma etching and monolithic electrodes with catalyst layers and fuel channels were realized. A preliminary DMFC prototype successfully demonstrated power generation of 2mW/cm2.

Radio Frequency Interference Characteristics of Plate-Like Soft Magnetic Powders-Polymer Composites

2006 ◽  
Vol 510-511 ◽  
pp. 826-829
Author(s):  
Sang Woo Kim ◽  
Y.W. Yoon ◽  
G.Y. Kim ◽  
Kyung Sub Lee
Keyword(s):  
Radio Frequency ◽  
Polymer Composites ◽  
Electromagnetic Interference ◽  
Noise Suppression ◽  
Compaction Pressure ◽  
Complex Permeability ◽  
Al Alloy ◽  
Radio Frequency Interference ◽  
Soft Magnetic ◽  
Dielectric Resonance

Radio frequency interference characteristics of plate-like Fe-Si-Al alloy powders-polymer composites were investigated for effective noise suppression. Broadband reflection loss characteristics were exhibited in the composites below a critical compaction pressure of 1.56 x 108 N/m2, while narrowband characteristics were shown in the composites above the critical pressure. Although the composites at 2.34 x 108 N/m2 had the highest complex permeability and complex permittivity, the loss properties did not show the broadband characteristics. The peculiar broadband characteristics were obtained in the composites with wideband dependency of the imaginary part of permittivity and permeability. These findings led us to conclude that the broadband electromagnetic interference characteristics of the composites are caused by the coupling effects of magnetic and dielectric resonance in the radio frequency range.

Frequency Characterization of Ferrite Beads in the Microwave Range for Nonlinear Applications

2014 ◽  
Vol 802 ◽  
pp. 552-557
Author(s):  
Lauro Paulo Silva Neto ◽  
J.O. Rossi ◽  
P.A.G. Dias ◽  
J.J. Barroso
Keyword(s):  
Transmission Lines ◽  
Electromagnetic Interference ◽  
Nonlinear Behavior ◽  
Complex Permeability ◽  
Microwave Range ◽  
Limited Information ◽  
Low Frequencies ◽  
High Power Microwave ◽  
Low Pass ◽  
Low Pass Filters

Ferrite beads are ferromagnetic materials that exhibit a small inductance at low frequencies, becoming resistive at high frequencies. These devices are used as low pass filters for reducing electromagnetic interference (EMI) in communications and power electronics because the resistive losses attenuate the undesired frequencies. As ferrite beads have a nonlinear behavior with current and frequency they have been used in nonlinear transmission lines (NLTLs) for high power microwave generation in space and defense applications. In this work, high frequency ferrite beads are characterized in the frequency range up to 1 GHz by measuring S11 reflection parameter in order to calculate their complex permeability and losses, key parameters in the design of NLTLs. In addition, X-ray diffraction (XRD) is used to identify their chemical element composition. Finally, the motivation for this work is basically due to the limited information on ferrite materials provided by the manufacturers.

A model-based approach for inspection of aeronautical multi-layered structures by eddy currents

2019 ◽  
Vol 38 (1) ◽  
pp. 382-394 ◽  
Author(s):  
Long Thanh Cung ◽  
Nam Hoang Nguyen ◽  
Pierre Yves Joubert ◽  
Eric Vourch ◽  
Pascal Larzabal
Keyword(s):  
Least Squares ◽  
Layer Thickness ◽  
Eddy Current ◽  
Eddy Currents ◽  
Metal Layer ◽  
Estimation Error ◽  
Eddy Current Method ◽  
Content Type ◽  
Model Based ◽  
Inversion Technique

Purpose The purpose of this paper is to propose an approach, which is easy to implement, for estimating the thickness of the air layer that may separate metallic parts in some aeronautical assemblies, by using the eddy current method. Design/methodology/approach Based on an experimental study of the coupling of a magnetic cup core coil sensor with a metallic layered structure (consisting of first metal layer/air layer/second metal layer), which is confirmed by finite element modelling simulations, an inversion technique relying on a polynomial forward model of the coupling is proposed to estimate the air layer thickness. The least squares and the nonnegative least squares algorithms are applied and analysed to obtain the estimation results. Findings The choice of an appropriate inversion technique to optimize the estimation results is dependent on the signal-to-noise ratio of measured data. The obtained estimation error is smaller than a few percent, for both simulated and experimental data. The proposed approach can be used to estimate both the air layer thickness and the second metal layer thickness simultaneously/separately. Originality/value This model-based approach is easy to implement and available to all types of eddy current sensors.

Electromagnetic interference shielding materials: recent progress, structure design, and future perspective

2022 ◽  
Author(s):  
Xiao-Yun Wang ◽  
Si-Yuan Liao ◽  
Yan-Jun Wan ◽  
Peng-Li Zhu ◽  
You-Gen Hu ◽  
...  
Keyword(s):  
Electromagnetic Interference ◽  
Recent Progress ◽  
Near Field ◽  
Structure Design ◽  
Measurement Methods ◽  
Future Perspective ◽  
Far Field ◽  
Future Perspectives ◽  
Electromagnetic Interference Shielding ◽  
Novel Structure

Novel structure design and shielding mechanism of various shielding materials are critically reviewed. Measurement methods of far-field and near-field shielding are presented. Challenges and future perspectives for shielding materials are discussed.

scholarly journals A Review on Synthesis and Characterizations of Mixed Nickel-Zinc Ferrites

2021 ◽  
pp. 189-217
Author(s):  
A. Kaur
Keyword(s):  
Electromagnetic Interference ◽  
Eddy Currents ◽  
Medical Science ◽  
Low Frequency ◽  
Industrial Applications ◽  
Research Progress ◽  
Intelligent Transport System ◽  
Semiconductor Memory ◽  
Nickel Zinc ◽  
Communication Devices

Nanotechnology, when this word comes in mind, it gives deep thought of new development in communication, medical science, intelligent transport system and many more. Ferrites nanoparticles have great significance owing to their amazing chemical and physical properties. In modern era we are developing materials for microwave applications and communication devices. Before the discovery of semiconductor memory chips, ferrites were the major form for electronic memory used in computers. Scientist have been studying and working with nanoparticles in magnetically guided drug delivery. The reactivity of material increases by the use of nanoparticles of that material. The dielectric characteristics of ferrites lean on diverse factors for instance methods of preparations and chemical composition. In various studies it has been found that their conductivity has dependence on temperature, composition and frequency. Among the various kinds of ferrites, Ni–Zn ferrites are viewed as the most adaptable ferrites as a result of their novel characteristics for applications at high frequency. The Ni-Zn ferrites are exploited as core materials in a variety of EM devices as well as have broad range of industrial applications e.g. inductors, microwave devices, power supplies, high and low frequency transformer cores, electromagnetic interference (EMI) suppressions and antenna rods. These broad ranges of applications are owing to their high resistivity, low eddy currents, high saturation magnetization, chemical stability and high Curie temperature. In view of this, the present chapter deals with the research progress on nickel-zinc ferrites in the bulk as well as nano size.

High-voltage monitoring by the fiber-optic recirculating measuring system

2020 ◽  
pp. 38-44
Author(s):  
A. V. Polyakov ◽  
M. A. Ksenofontov
Keyword(s):  
Optical Fibers ◽  
High Voltage ◽  
Optical Sensors ◽  
Electromagnetic Interference ◽  
Fiber Optic ◽  
Electric Power Industry ◽  
Measuring System ◽  
Voltage Range ◽  
External Electromagnetic Fields ◽  
Optic Communication

Optical technologies for measuring electrical quantities attract great attention due to their unique properties and significant advantages over other technologies used in high-voltage electric power industry: the use of optical fibers ensures high stability of measuring equipment to electromagnetic interference and galvanic isolation of high-voltage sensors; external electromagnetic fields do not influence the data transmitted from optical sensors via fiber-optic communication lines; problems associated with ground loops are eliminated, there are no side electromagnetic radiation and crosstalk between the channels. The structure and operation principle of a quasi-distributed fiber-optic high-voltage monitoring system is presented. The sensitive element is a combination of a piezo-ceramic tube with an optical fiber wound around it. The device uses reverse transverse piezoelectric effect. The measurement principle is based on recording the change in the recirculation frequency under the applied voltage influence. When the measuring sections are arranged in ascending order of the measured effective voltages relative to the receiving-transmitting unit, a relative resolution of 0,3–0,45 % is achieved for the PZT-5H and 0,8–1,2 % for the PZT-4 in the voltage range 20–150 kV.

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