scholarly journals Shielding effectiveness measurement of cement-graphite block in between 3.8 GHz to 6 GHz

2020 ◽  
Vol 9 (2) ◽  
pp. 716-721
Author(s):  
S. L. Yeoh ◽  
S. K. Yee ◽  
N. T. J. Ong ◽  
S. H. Dahlan ◽  
C. K. Sia
Keyword(s):  
Electronic Devices ◽  
Graphite Powder ◽  
Shielding Effectiveness ◽  
Frequency Range ◽  
Graphite Block ◽  
Radiation Level ◽  
Cement Block ◽  
Effectiveness Measurement ◽  
Network Analyser

Due to proliferation of electronic devices, the electromagnetic field (EMF) exposure affect human health in long term. On the other hand the operation electronic devices will be affected if the radiation level is too high. To reduce the radiation exposure, shielding is always used. Instead of building a shielding enclosure inside a building, it is more practical to improve the shielding capability of the building itself. Hence, this project intend to investigate the shielding effectiveness (SE) of cement added with graphite. Eight cement-graphite specimens with different percentages (0%, 3%, 7%, 11%, 15%, 19%, 25% and 30%) are prepared. They have been casted into the waveguide mold with size of 4.75 cm x 1 cm x 2.22 cm and taken for measurement directly. The SE measurement setup involve a pair of waveguide with frequency range of 3.8 GHz to 6 GHz and vector network analyser (VNA). Throughout the study, it is found that the percentage of graphite powder will affect the SE of the specimens. The SE is independent on its curing duration. More than 11% of graphite is needed to improve the SE of cement block in between 3.8 GHz to 6 GHz. The highest SE of 33 dB is achieved when the sample contains 30% of graphite with thickness of 1cm.

scholarly journals Design of a Miniaturized Rectangular Multiturn Loop Antenna for Shielding Effectiveness Measurement

Sensors ◽  
2020 ◽  
Vol 20 (11) ◽  
pp. 3178
Author(s):  
Sangwoon Youn ◽  
Tae Heung Lim ◽  
Eunjung Kang ◽  
Dae Heon Lee ◽  
Ki Baek Kim ◽  
...  
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Loop Antenna ◽  
Shielding Effectiveness ◽  
Frequency Range ◽  
Ferrite Core ◽  
Very Low Frequency ◽  
Effectiveness Measurement ◽  
Antenna Factor ◽  
Plastic Case

This paper proposes a novel miniaturized rectangular loop antenna sensor consisting of a multiturn wire and a cuboid ferrite core. The lateral surface of the ferrite core is tightly wound by the multiturn wire. To verify its feasibility, the antenna sensor is fabricated, and the antenna factor (AF) levels are measured using the three-antenna method from the very low frequency (VLF) to the high-frequency (HF) bands. The measured AF levels are 31.8 dB (with a covering plastic case) and 33.1 dB (without a covering plastic case) at 30 kHz. In addition, the proposed antenna is employed in the shielding effectiveness measurement of a small commercial cabinet to observe its suitability for shielding effectiveness (SE) measurement of small shielding enclosures. The SE values averaged over the frequency range from 10 kHz to 3 MHz are 4.1 dB and 12 dB in the horizontal and vertical polarizations, respectively.

Effect of dielectric and magnetic nanofillers on electromagnetic interference shielding effectiveness of carbon/epoxy composites

2021 ◽  
pp. 002199832110526
Author(s):  
Hafiz Shehbaz Ahmad ◽  
Tanveer Hussain ◽  
Yasir Nawab ◽  
Shuaib Salamat
Keyword(s):  
Silicon Carbide ◽  
Zinc Oxide ◽  
Electromagnetic Interference ◽  
Electronic Devices ◽  
Skin Depth ◽  
Shielding Effectiveness ◽  
Emi Shielding ◽  
Frequency Range ◽  
Electromagnetic Pollution ◽  
Emi Se

Tremendous development in electronic devices and their indiscriminate use has created a severe problem of electromagnetic pollution. Different types of electromagnetic interference (EMI) shielding materials and structures are used to protect electronic devices from the harmful effect of electromagnetic pollution. A present study was conducted to compare the effect of dielectric and magnetic nanofillers on electromagnetic shielding effectiveness (EMI SE) of carbon fiber reinforced composite structures (CFRC). Composites structures were developed using different dielectric and magnetic nanofillers. Effect of nanofillers on microwave absorption properties and reduction in electromagnetic pollution was investigated. Relationship between electrical conductivity and EMI shielding effectiveness in L, S, C, and X-frequency range was also studied. Among the dielectric nanofillers, silicon carbide showed excellent EMI SE in X-frequency range, while among magnetic nanofillers, zinc oxide showed excellent EMI shielding characteristics in a broad frequency range of 100 MHz to 13.6 GHz. Among magnetic nanofillers, CFRC with zinc oxide nanofillers showed the lowest skin depth value of 3.32 × 10−4 mm and among dielectric nanofiller, CFRC with silicon carbide nanofillers gave the lowest skin depth value of 6.49 × 10−4 mm, implying their excellent potential in EMI shielding applications.

Improving the electromagnetic shielding of nickel/polyaniline coated polytrimethylene-terephthalate knitted fabric by optimizing the electroless plating conditions

2016 ◽  
Vol 87 (8) ◽  
pp. 902-912 ◽  
Author(s):  
Hu Jiyong ◽  
Li Guohao ◽  
Shi Junhui ◽  
Yang Xudong ◽  
Ding Xin
Keyword(s):  
Electroless Plating ◽  
Electromagnetic Interference ◽  
Electronic Devices ◽  
Electroless Nickel ◽  
Electromagnetic Shielding ◽  
Health Issues ◽  
Shielding Effectiveness ◽  
Frequency Range ◽  
Electromagnetic Shielding Effectiveness

To solve electromagnetic interference of electronic devices and health issues by the expansion of the electronic industry and the extensive use of electronic equipment, flexible and stretchable conductive elastic textiles are beneficial. This study prepared conductive Ni/polyaniline (PANi)/polytrimethylene-terephthalate (PTT) composite fabric by in situ chemical polymerization and electroless nickel plating. Their direct current electrical resistance and the shielding efficiency energy were tested. Furthermore, the effect of electroless plating conditions was investigated on surface resistivity and electromagnetic shielding effectiveness (EMSE) of the composite fabric, and the correlation between electrical resistivity and EMSE was explored. The results show that the shielding efficiency energy of Ni/PANi/PTT composite fabric optimized can reach more than 40 dB and at a given frequency it has an inverse parabolic relation with the electroless plating conditions. In addition, when the electroless plating conditions is the determinant, the SE has little change in the electromagnetic wave frequency, especially in the frequency range of 600 MHz or more. It is concluded that the EMSE of the Ni/PANi/PTT conductive fabrics could be tailored by modifying the chemical reagent contents in the electroless plating solution.

scholarly journals Ultrathin, Lightweight, and Flexible CNT Buckypaper Enhanced Using MXenes for Electromagnetic Interference Shielding

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Rongliang Yang ◽  
Xuchun Gui ◽  
Li Yao ◽  
Qingmei Hu ◽  
Leilei Yang ◽  
...  
Keyword(s):  
Electromagnetic Interference ◽  
High Performance ◽  
Electronic Devices ◽  
Deposition Process ◽  
Shielding Effectiveness ◽  
Emi Shielding ◽  
Emi Shielding Effectiveness ◽  
X Band ◽  
Wearable Electronic Devices ◽  
Emi Se

AbstractLightweight, flexibility, and low thickness are urgent requirements for next-generation high-performance electromagnetic interference (EMI) shielding materials for catering to the demand for smart and wearable electronic devices. Although several efforts have focused on constructing porous and flexible conductive films or aerogels, few studies have achieved a balance in terms of density, thickness, flexibility, and EMI shielding effectiveness (SE). Herein, an ultrathin, lightweight, and flexible carbon nanotube (CNT) buckypaper enhanced using MXenes (Ti3C2Tx) for high-performance EMI shielding is synthesized through a facile electrophoretic deposition process. The obtained Ti3C2Tx@CNT hybrid buckypaper exhibits an outstanding EMI SE of 60.5 dB in the X-band at 100 μm. The hybrid buckypaper with an MXene content of 49.4 wt% exhibits an EMI SE of 50.4 dB in the X-band with a thickness of only 15 μm, which is 105% higher than that of pristine CNT buckypaper. Furthermore, an average specific SE value of 5.7 × 104 dB cm2 g−1 is exhibited in the 5-μm hybrid buckypaper. Thus, this assembly process proves promising for the construction of ultrathin, flexible, and high-performance EMI shielding films for application in electronic devices and wireless communications.

APPLICATION OF MEASUREMENT METHODS FOR THE FREQUENCY RANGE 2-150 KHZ TO LONG-TERM MEASUREMENTS IN PUBLIC LOW VOLTAGE NETWORKS

2021 ◽  
Author(s):  
V. Khokhlov ◽  
J. Meyer ◽  
D. Ritzmann ◽  
S. Lodetti ◽  
P. S. Wright ◽  
...  
Keyword(s):  
Low Voltage ◽  
Measurement Methods ◽  
Frequency Range

Oscillations and Long-Lasting Correlations in a Model of the Lateral Geniculate Nucleus and Visual Cortex

2000 ◽  
Vol 84 (4) ◽  
pp. 1863-1868 ◽  
Author(s):  
Kyle L. Kirkland ◽  
Adam M. Sillito ◽  
Helen E. Jones ◽  
David C. West ◽  
George L. Gerstein
Keyword(s):  
Experimental Data ◽  
Visual Cortex ◽  
Cell Membrane ◽  
Lateral Geniculate Nucleus ◽  
Feedback Inhibition ◽  
Frequency Range ◽  
Lateral Geniculate ◽  
Low Threshold ◽  
Thalamocortical System

We have previously developed a model of the corticogeniculate system to explore cortically induced synchronization of lateral geniculate nucleus (LGN) neurons. Our model was based on the experiments of Sillito et al. Recently Brody discovered that the LGN events found by Sillito et al. correlate over a much longer period of time than expected from the stimulus-driven responses and proposed a cortically induced slow covariation in LGN cell membrane potentials to account for this phenomenon. We have examined the data from our model, and we found, to our surprise, that the model shows the same long-term correlation. The model's behavior was the result of a previously unsuspected oscillatory effect, not a slow covariation. The oscillations were in the same frequency range as the well-known spindle oscillations of the thalamocortical system. In the model, the strength of feedback inhibition from the cortex and the presence of low-threshold calcium channels in LGN cells were important. We also found that by making the oscillations more pronounced, we could get a better fit to the experimental data.

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

scholarly journals Practice and perspectives of using ultrasensitive magnetometers in biomedical research.

2021 ◽  
Author(s):  
Yu.V. Maslennikov ◽  
◽  
◽  
Keyword(s):  
Magnetic Field ◽  
Biomedical Research ◽  
Magnetic Measurements ◽  
Signal To Noise Ratio ◽  
Frequency Range ◽  
Optically Pumped ◽  
Technical Solutions ◽  
Further Development ◽  
The Magnetic Field

There are a large number of sensors for measuring the magnetic field of biological objects. They are characterized by the type of the measured physical parameter (magnetic field strength, magnetic flux, etc.), the level of intrinsic sensitivity, and the frequency range of the recorded signals. The long-term practice of studying biomagnetic signals shows that only SQUID-based magnetometers and optically pumped magnetometers have sensitivity levels sufficient for recording biomagnetic signals with the required signal-to-noise ratio. This chapter reflects the main directions of using such magnetometers and methods of magnetic measurements in biomedical research, gives examples of existing technical solutions, and shows possible ways of their further development.

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