scholarly journals Numerical Assessment of Electromagnetic Radiated Emissions from an UWB Radiators Located Inside Metallic Enclosures with Small Air-Flow Openings

2018 ◽  
Vol 15 (2) ◽  
pp. 155
Author(s):  
Mohammed M Bait-Suwailm ◽  
Boudelliou A Boudelliou ◽  
Naser Al-Tarhuni
Keyword(s):  
Electromagnetic Interference ◽  
Heat Dissipation ◽  
Air Flow ◽  
Electronic Devices ◽  
Wide Band ◽  
Ultra Wide Band ◽  
Shielding Effectiveness ◽  
Numerical Assessment ◽  
Radiated Emissions ◽  
Circular Holes

Shielding effectiveness of electronic devices and computing devices is  essential at design stages. Devices should pass electromagnetic interference/compatibility tests for certification purposes. In this paper, we investigate the electromagnetic radiation leakage from modern personal computers and mobile electronic devices due to an ultra-wide band source of noise. Openings and slots are always unavoidable in electronic devices, for instance openings in computers for air-flow and heat dissipation. Three different designs of enclosure’s covers with apertures are modeled for this purpose. The three covers cases comprise the use of rectangular arranged circular holes, hexagonal arranged circular holes, and square openings. For comparison purposes, a shielded enclosure with no openings is considered. The shielding effectiveness is numerically assessed here by capturing electric field strength that is modeled using probes located at two different distances, near- and far-away from the metallic enclosure.

scholarly journals Numerical Assessment of Electromagnetic Radiated Emissions from an UWB Radiators Located Inside Metallic Enclosures with Small Air-Flow Openings

2018 ◽  
Vol 15 (2) ◽  
pp. 55
Author(s):  
Mohammed M Bait-Suwailm ◽  
Boudelliou A Boudelliou ◽  
Naser Al-Tarhuni
Keyword(s):  
Electromagnetic Interference ◽  
Heat Dissipation ◽  
Air Flow ◽  
Electronic Devices ◽  
Wide Band ◽  
Ultra Wide Band ◽  
Shielding Effectiveness ◽  
Numerical Assessment ◽  
Radiated Emissions ◽  
Circular Holes

Shielding effectiveness of electronic devices and computing devices is  essential at design stages. Devices should pass electromagnetic interference/compatibility tests for certification purposes. In this paper, we investigate the electromagnetic radiation leakage from modern personal computers and mobile electronic devices due to an ultra-wide band source of noise. Openings and slots are always unavoidable in electronic devices, for instance openings in computers for air-flow and heat dissipation. Three different designs of enclosure’s covers with apertures are modeled for this purpose. The three covers cases comprise the use of rectangular arranged circular holes, hexagonal arranged circular holes, and square openings. For comparison purposes, a shielded enclosure with no openings is considered. The shielding effectiveness is numerically assessed here by capturing electric field strength that is modeled using probes located at two different distances, near- and far-away from the metallic enclosure.

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.

scholarly journals Effects of Aperture Size on <i>Q</i> factor and Shielding Effectiveness of a Cubic Resonator

2017 ◽  
Vol 15 ◽  
pp. 169-173 ◽  
Author(s):  
Stefan Parr ◽  
Stephan Chromy ◽  
Stefan Dickmann ◽  
Martin Schaarschmidt
Keyword(s):  
Time Domain ◽  
Electromagnetic Interference ◽  
Electronic Devices ◽  
Coupling Mechanism ◽  
Q Factor ◽  
Aperture Size ◽  
Shielding Effectiveness ◽  
Worst Case ◽  
Resonant Frequencies ◽  
Broadband Signal

Abstract. The EMC properties of a cubic metallic shield are highly affected by its resonances. At the resonant frequencies, the shielding effectiveness (SE) collapses, which results in high field strengths inside the cavity. This can cause failure or even breakdown of electronic devices inside the shield. The resonant behaviour is mainly determined by the quality or Q factor of the shield. In this paper, the effects of the aperture size on the Q factor and the SE of an electrically large, cubic shield are analysed. At first, a method is developed in order to determine the Q factor based on the resonance behaviour of the shield in time domain. Only the first resonance of the shield is considered therefore. The results are evaluated for different aperture diameters and compared with theory for the Q factor. The dominant coupling mechanism of electromagnetic energy into the shield is thus identified. Then the effect of aperture size on the SE is analysed. The excitation of resonances is very probable if the interfering signal is an ultrawideband (UWB) pulse, which constitutes a typical intentional electromagnetic interference (IEMI) scenario. Therefore, the relation between aperture size and SE is analysed using the theory of the transient SE for a broadband signal with a constant spectral density distribution. The results show, that a worst case aperture size exists, where the SE has its minimum.

Evaluation of PCB Shielding Characteristic in Near Field

2017 ◽  
Vol 5 (3) ◽  
pp. 542
Author(s):  
Yih Jian Chuah ◽  
Mohd Tafir Mustaffa
Keyword(s):  
Electromagnetic Interference ◽  
High Frequency ◽  
Near Field ◽  
Electronic Devices ◽  
The Other ◽  
Shielding Effectiveness ◽  
Electronic Industry ◽  
Common Solution ◽  
The Common ◽  
Simulation Results

Wireless electronic devices nowadays always operate in high frequency while having small and compact form factor which led to electromagnetic interference among traces and components. PCB shielding is the common solution applied in electronic industry to mitigate electromagnetic interference. In this paper, PCB shielding characteristics such as shield’s thickness, height, and ground via spacing in PCB boards were evaluated in near field. Test boards with various ground via spacing were fabricated and evaluated by using 3D Electromagnetic scanner. On the other hand, shields with various thickness and height were modeled and evaluated through simulation. Results suggested that shielding effectiveness could be improved by having greater shield’s height with smaller ground via spacing in shielding ground tracks. Shielding effectiveness can be improved by 1 dB with every step of 0.5 mm increase in shield’s height. Besides that, approximately 0.5 dB improvement in shielding effectiveness with every step of 1 mm decrease in ground via spacing. Furthermore, greater shield’s thickness can contribute better shielding effectiveness for operating frequency below 300 MHz.

scholarly journals Ultrathin flexible graphene films with high thermal conductivity and excellent EMI shielding performance using large-sized graphene oxide flakes

RSC Advances ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 1419-1427 ◽  
Author(s):  
Shaofeng Lin ◽  
Su Ju ◽  
Jianwei Zhang ◽  
Gang Shi ◽  
Yonglyu He ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Graphene Oxide ◽  
Electromagnetic Interference ◽  
Electronic Devices ◽  
High Thermal Conductivity ◽  
Shielding Effectiveness ◽  
Emi Shielding ◽  
Emi Shielding Effectiveness ◽  
Graphene Films ◽  
Thermal Conducting

As the demand for wearable and foldable electronic devices increases rapidly, ultrathin and flexible thermal conducting films with exceptional electromagnetic interference (EMI) shielding effectiveness (SE) are greatly needed.

Electromagnetic Field Shielding Fabrics with Increased Comfort Properties

2013 ◽  
Vol 677 ◽  
pp. 161-168 ◽  
Author(s):  
Veronika Safarova ◽  
Jiří Militký
Keyword(s):  
Electromagnetic Interference ◽  
Electronic Devices ◽  
Health Issues ◽  
Shielding Effectiveness ◽  
Electronic Industry ◽  
Metal Grid ◽  
Shielding Properties ◽  
Fabrication And Characterization ◽  
Electromagnetic Signals

The expansion of the electronic industry and the extensive use of electronic equipment in communications, computations, automations, biomedicine, space, and other purposes have led to problems such as electromagnetic interference of electronic devices and health issues. For reasons given above, a demand for protection of human being, sensitive electronic and electrotechnic appliances against undesirable influence electromagnetic signals and troublesome charges raised. This paper presents the present state of a fabrication and characterization of multifunctional metal hybrid fabrics with increased resistivity to electromagnetic smog at conserving basic properties of textile structures designated for clothing purposes. The parameters influencing electromagnetic (EM) shielding properties of the hybrid fabrics were investigated. It was shown that the EM shielding effectiveness of the fabrics could be tailored by modifying the metal content, metal grid size and geometry. Furthermore, correlation between electrical properties and EM shielding effectiveness and comfort properties was studied.

Wireless Corrosion Monitoring Sensors Based on Electromagnetic Interference Shielding of RFID Transponders

CORROSION ◽  
10.5006/3384 ◽  
2020 ◽  
Vol 76 (4) ◽  
pp. 411-423 ◽  
Author(s):  
Youliang He
Keyword(s):  
Radio Frequency Identification ◽  
Electromagnetic Interference ◽  
Electronic Devices ◽  
Signal Strength ◽  
Metal Sheet ◽  
Corrosion Monitoring ◽  
Shielding Effectiveness ◽  
Emi Shielding ◽  
Partial Restoration ◽  
Rf Signal

Electromagnetic interference (EMI) shielding is a common technology used to protect electronic devices from the interference of environmental noise or to prevent the radiation of electromagnetic waves from electronic devices to the environment. In this research, the EMI shielding principle was utilized to develop a simple and cost-effective wireless corrosion-monitoring sensor. A thin metal sheet (e.g., a steel foil) similar to the material to be monitored was attached onto the surface of a radio frequency identification (RFID) transponder and served as an RF shielding layer to block the communication between the RFID transponder and the transceiver. The shielded transponder (the sensor) was then subjected to corrosion exposure, which caused the corrosion of the shielding metal sheet and led to the degradation of the shielding effectiveness. By chronically recording the change of the RF signal strength and the amount of corrosion that occurred, a correlation could be established between the signal strength and the corrosion rate. In this way, a simple wireless corrosion-monitoring sensor was developed. Steel sheets with various thicknesses (50 μm to 250 μm) were used as shielding layers on ultra-high-frequency RFID transponders, and the sensors covered by these various sheets behaved differently during corrosion exposure. The microstructure change of the shielding material was characterized by optical microscopy and scanning electron microscopy, which revealed the uneven thinning and final damage of the shielding layer, leading to the (partial) restoration of the RF signal.

A highly stretchable, easily processed and robust metal wire-containing woven fabric with strain-enhanced electromagnetic shielding effectiveness

2021 ◽  
pp. 004051752199489 ◽  
Author(s):  
Yong Wang ◽  
Stuart Gordon ◽  
Weidong Yu ◽  
Zongqian Wang
Keyword(s):  
Electromagnetic Interference ◽  
Specular Reflection ◽  
Electronic Devices ◽  
Single Layer ◽  
Electromagnetic Shielding ◽  
Woven Fabric ◽  
Shielding Effectiveness ◽  
Fabric Structure ◽  
Highly Stretchable ◽  
Electromagnetic Shielding Effectiveness

Textiles that contain integrated conducting components are drawing attention for their ability to mitigate electromagnetic radiation pollution. Maintaining effective and robust electromagnetic shielding effectiveness (EMSE) under different modes, e.g. stretching, bending and washing, is of importance in protecting humans and information-sensitive electronic devices from exposure to electromagnetic interference. In this work, a weft-stretchable, conductive fabric (W-SCF) was specially manufactured for electromagnetic shielding characterization by integrating stainless steel filament (SSF) in the weft direction. The results demonstrate that our as-prepared W-SCF was effective for shielding purpose with its EMSE dependent on the orientation of the SSF within the fabric structure. Specular reflection caused by the close arrangement of the SSF and the lower electrical resistance of the fabric on per unit area basis were responsible for the enhanced shielding properties when the fabric was stretched. Furthermore, using the fabric in a 90°/90° laminated form improved the EMSE values compared with a single layer and a 0°/90° laminated versions. Importantly, the W-SCF exhibited resistance to 10 laundering cycles, 20 stretching cycles (at 25% extension), 50 bending cycles and 100 abrasion cycles, demonstrating its robustness and durability. This work is believed to take a new step in development of reliable and advance shielding materials for special protective application.

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