scholarly journals Optimized 3-D electromagnetic models of composite materials in microwave frequency range: application to EMC characterization of complex media by statistical means

2017 ◽  
Vol 6 (2) ◽  
pp. 46
Author(s):  
S. Lalléchère
Keyword(s):  
Composite Materials ◽  
Electromagnetic Compatibility ◽  
Microwave Frequency ◽  
Electromagnetic Modeling ◽  
Shielding Effectiveness ◽  
Frequency Range ◽  
Homogenization Model ◽  
Electromagnetic Models ◽  
Electromagnetic Mixing

The aim of this proposal is to demonstrate the ability of tridimensional (3-D) electromagnetic modeling tool for the characterization of composite materials in microwave frequency band range. Indeed, an automated procedure is proposed to generate random materials, proceed to 3-D simulations, and compute shielding effectiveness (SE) statistics with finite integration technique. In this context, 3-D electromagnetic models rely on random locations of conductive inclusions; results are compared with classical electromagnetic mixing theory (EMT) approaches (e.g. Maxwell-Garnett formalism), and dynamic homogenization model (DHM). The article aims to demonstrate the interest of the proposed approach in various domains such as propagation and electromagnetic compatibility (EMC).

scholarly journals Conductive textile structures and their contribution to electromagnetic shielding effectiveness

2020 ◽  
Vol 71 (05) ◽  
pp. 432-437
Author(s):  
Ion Razvan Radulescu ◽  
Lilioara Surdu ◽  
Bogdana Mitu ◽  
Cristian Morari ◽  
Marian Costea ◽  
...  
Keyword(s):  
Electromagnetic Compatibility ◽  
Modern Technology ◽  
Electromagnetic Shielding ◽  
Shielding Effectiveness ◽  
Frequency Range ◽  
Conductive Coatings ◽  
Tem Cell ◽  
Conductive Yarns ◽  
Conductive Textile ◽  
Electromagnetic Shielding Effectiveness

Fabrics for electromagnetic shielding are especially relevant in nowadays context, contributing to human’s protection and wellbeing and to proper functioning of electronic equipment, in relation to electromagnetic compatibility. Fabrics with electromagnetic shielding properties employ two main technologies, namely insertion of conductive yarns and application of conductive coatings. Magnetron sputtering is a modern technology to enable conductive coatings with thickness in the range of nanometers onto fabrics. This paper aims to analyze contribution of various conductive textile structures out of both fabrics with inserted conductive yarns and coatings to Electromagnetic shielding effectiveness (EMSE). EMSE was measured in the frequency range of 0.1–1000 MHz by using a TEM cell according to standard ASTM ES-07. Results show a gain of 10–25 dB when introducing silver yarns in warp/ weft direction, a variation of 5–35 dB between conductive yarns out of silver and stainless steel and an up to 12 dB gain out of thin copper coating by magnetron plasma onto the fabrics with inserted conductive yarns

Microwave Photoconductivity Measurements to Characterize Semiconductors

1990 ◽  
Vol 189 ◽  
Author(s):  
M. Kunst
Keyword(s):  
Semiconductor Devices ◽  
Microwave Frequency ◽  
Frequency Range ◽  
General Survey ◽  
Characterization Techniques ◽  
Transient Photoconductivity

ABSTRACTAfter a general survey of characterization techniques the use of transient photoconductivity measurements in the microwave frequency range for the characterization of semiconductors and semiconductor devices for (opto)electronic applications is treated. Experimental details and applications of these measurements are given.

scholarly journals An Inexpensive Route to Synthesize High-Purity CrO2 for EMI Shielding in X-Band Frequencies

2012 ◽  
Vol 2012 ◽  
pp. 1-4 ◽  
Author(s):  
Vivek Verma ◽  
Shahab Ahmad ◽  
Abdullah Dar ◽  
R. Kotnala
Keyword(s):  
High Purity ◽  
Microwave Frequency ◽  
External Pressure ◽  
Shielding Effectiveness ◽  
Emi Shielding ◽  
Frequency Range ◽  
Absorption Properties ◽  
Microwave Absorption Properties ◽  
X Band ◽  
Simplified Procedure

Rod-shaped high-purity samples of CrO2 have been synthesized by an inexpensive and simplified procedure. Here, we have prepared pure CrO2 without applying any external pressure or control it during synthesis. The sample prepared exhibited an improvement in saturation magnetization values, 68 emu/g at 300 K, 136 emu/g at 80 K, and uniform grained microstructure. The complex permittivity, permeability, and microwave absorption properties of high-purity CrO2 sample were investigated in the 8.2–12.2 GHz (X-band) microwave frequency range. Microwave measurements have shown the high shielding effectiveness due to absorption (SEA) of 20.3 dB. The high value of SEA suggests that CrO2 can be used as a promising electromagnetic shielding, EMI, material in 8.2–12.2 GHz (X-band) microwave frequency range.

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

2019 ◽  
Vol 33 (01n03) ◽  
pp. 1940020 ◽  
Author(s):  
Ming Gong ◽  
Shou-Guang Sun ◽  
Lin Sun ◽  
Ai-Qin Tian ◽  
Qiang Li
Keyword(s):  
Computer Simulation ◽  
Composite Materials ◽  
Carbon Fiber ◽  
Fiber Composite ◽  
Electromagnetic Shielding ◽  
Shielding Effectiveness ◽  
Frequency Range ◽  
Simulation Technology ◽  
Carbon Fiber Composite ◽  
Fiber Composite Materials

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.

Dielectric Studies of Admicelled Natural Rubber with Poly(3-Trimethoxysilylpropyl Methacrylate)

2013 ◽  
Vol 844 ◽  
pp. 373-376
Author(s):  
Suparat Nooma ◽  
Rathanawan Magaraphan
Keyword(s):  
Dielectric Constant ◽  
Composite Materials ◽  
Dielectric Properties ◽  
Chemical Modification ◽  
Natural Rubber ◽  
Microwave Frequency ◽  
Dielectric Studies ◽  
Frequency Range ◽  
Admicellar Polymerization ◽  
Methoxy Groups

In this work, 3-trimethoxysilylpropyl methacrylate (MPS) was used as a substrate for coating on natural rubber (NR) particles by admicellar polymerization. The incorporation of MPS monomer, consisting of silicon element and 3 reactive methoxy groups (R-Si(OCH3)), is expected to increase dielectric properties of NR. Under the admicellar polymerization, the R-Si(OCH3) groups can be hydrolyzed and condensed into polysiloxane existed on NR particles. This method aims to prepare composite materials from NR and MPS with various amounts of MPS. The effects of microwave frequency and chemical modification by admicellar polymerization were studied. The dielectric properties of admicelled natural rubber (adNR) with PMPS were investigated at 20 °C in a frequency range extended from MHz to GHz. The results showed that the dielectric constant of adNR increased with PMPS contents. To study the effect of crosslinking on the dielectric properties of adNR, the dielectric spectroscopy measurements were performed on prevulcanized and non-prevulcanized adNR. The investigation showed that the dielectric constant of non-prevulcanized adNR was less than prevulcanized adNR.

Characterization Of Thin Semiconductor Films For (Opto)Electronic Applications

1996 ◽  
Vol 430 ◽  
Author(s):  
J. R. Elmiger ◽  
H. Feist ◽  
M. Kunst
Keyword(s):  
Microwave Frequency ◽  
Semiconductor Films ◽  
Frequency Range ◽  
Transient Photoconductivity ◽  
Simple Set ◽  
Thin Semiconductor ◽  
Effective Mobility ◽  
Set Up

AbstractA simple set-up to measure the transient photoconductivity in the microwave frequency range is presented. The effective mobility is derived from the end of pulse transient photoconductivity. This can be used for the characterization of semiconductor films. Examples of measurements on a-Si:H films are given.

scholarly journals Analysis and Design of Absorbers for Electromagnetic Compatibility Applications

2021 ◽  
Author(s):  
Shiva Hayati Raad
Keyword(s):  
Electromagnetic Compatibility ◽  
Wave Spectrum ◽  
Low Frequency ◽  
Microwave Frequency ◽  
Frequency Range ◽  
Analysis And Design ◽  
Matching Layer ◽  
Pyramidal Absorbers ◽  
Graphene Material ◽  
Carbon Loading

Absorbers are one of the key components in the realm of electromagnetic compatibility. Depending on the frequency range of interest, different types of absorbers can be utilized for this purpose. This chapter introduces the analysis and modeling of ferrite-based absorbers for low-frequency applications (below 1 GHz) and discusses the issues encountered in their installation, resulting in air gaps. Later, different kinds of pyramidal absorbers, commonly used in the broadband microwave frequency range (above 1 GHz), are presented, and analytical and numerical approaches for predicting their performance are reviewed. The combination of the ferrite tile and pyramidal dielectric absorbers is also provided. Then, some practical aspects of designing hybrid absorbers, including the influence of carbon loading and matching layer on their performance, are mentioned. Finally, the absorber operating frequency extension to the millimeter-wave spectrum using metamaterial structures or graphene material is presented.

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