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Conjugated Polymers
Published in Narendra Pal Singh Chauhan, Functionalized Polymers, 2021
With the extensive use of wireless communication and network, the demand for electromagnetic shielding materials has been high. The first candidate for electromagnetic shielding was metal sheets, but metals have the disadvantages of corrosion, non-flexibility, high price and heavy weight (Gahlout and Choudhary 2019, Yan et al. 2017). Conducting polymers found many applications in various fields as soon as they were discovered. Conducting polymers as synthetic metals have been considered as alternatives for metals in many fields including electromagnetic shielding (Gahlout and Choudhary 2019, Hosseini et al. 2014, 2015).
Design of Frequency Selective Surface (FSS) Printed Antennas
Published in Binod Kumar Kanaujia, Surendra Kumar Gupta, Jugul Kishor, Deepak Gangwar, Printed Antennas, 2020
Kanishka Katoch, Naveen Jaglan, Samir Dev Gupta, Binod Kumar Kanaujia
To avoid the interference created by any other device which can degrade the performance of the antennas, electromagnetic shielding is necessary. FSS due to its good transmission and reflection properties are a suitable candidate for this application [99]. In [100], a FSS consisting of cross-dipoles and rings imprinted on the opposite sides of the substrate was presented and it exhibited a stopband of 7.5 GHz ranging from 6.5 to 14 GHz, as shown in Figure 12.22a. This FSS structure provided effective shielding in X-band and Ka-band with minimum attenuation of 20–35 dB. Electromagnetic shielding can also be achieved using reconfigurable frequency-selective surfaces (RFSS) [101], as shown in Figure 12.22b. In this, two pairs of squares were connected together to create an individual unit cell. Frequency tuning was obtained by varying the distance between the unit cells, mechanically. The frequency shifted toward the left with the increase in the distance between the FSS, and vice versa. This structure provided electromagnetic shielding for WiMAX (3.5 GHz), WLAN (5 GHz), and ISM/WiMAX bands (5.8 GHz). The reconfiguration range of 3.5–8.2 GHz was obtained by varying the space between the unit cells.
Estimation of shielding effectiveness of the lossy infinite plane with periodic circular apertures
Published in Rodolfo Dufo-López, Jaroslaw Krzywanski, Jai Singh, Emerging Developments in the Power and Energy Industry, 2019
L.L. Chen, W.X. Bai, C.Q. Jiao
Due to the widespread use of electronic equipment sensitive to space electromagnetic disturbances, electromagnetic shielding as an electromagnetic disturbance suppression technology has received extensive attention (Garcia-Perez. et al. 2017, Vieira Valente. et al. 2017). Electromagnetic shielding is a practice of reducing the electromagnetic field in space by blocking the field with a metal material. The shielding effectiveness (SE) used to measure shielding performance is defined as SE=20log10(1/T)
The influence of wave-absorbing functional particles on the electromagnetic properties and the mechanical properties of coated fabrics
Published in The Journal of The Textile Institute, 2025
Yuanjun Liu, Yongtao Yu, Xiaoming Zhao
The shielding effectiveness is one of the important indices characterizing electromagnetic shielding performance, which refers to the intensity of the electric field, the strength of the magnetic field or the ratio of power before and after placing shielding materials (Jia et al., 2018). The value of the shielding effectiveness is positive, the greater the value, the better the shielding effect. According to the practical application, the requirements for the shielding effectiveness of shielding materials are different, SE ≥ 20 dB is generally considered (namely the 90% of electromagnetic waves are shielded), the material has the good shielding effect. The device testing the shielding effectiveness is the vector network analyzer, the test method adopted the flange coaxial method with the higher accuracy in “the measuring methods of electromagnetic shielding materials” (Çat et al., 2018).
An investigation on electromagnetic shielding effectiveness of metallic enclosure depending on aperture position
Published in Journal of Microwave Power and Electromagnetic Energy, 2023
Electromagnetic shielding is one of the mandatory protections against external electromagnetic interference leakage onto electronic circuits besides suppressing the propagation of internal EMI to the outside (Bahadorzadeh and Moghaddasi 2006; Zhu et al. 2021; Güler 2022). Electronic circuits can be fully isolated against external EMI by putting them into an enclosure without any aperture on itself. However, this ideal circumstance cannot be achieved practically since aperture is strictly necessary in case of ventilation, heat dissipation or mounting a connector etc. which attenuates shielding performance of the enclosure. The shielding performance of an enclosure is measured with the shielding effectiveness (SE) which is expressed as the ratio of the electric or magnetic field magnitudes measured in the presence and absence of the enclosure (Robinson et al. 1998; Bahadorzadeh and Moghaddasi 2006; Güler 2022).
Analysing the shielding effectiveness of graphene sheet coated rectangular enclosure
Published in Electromagnetics, 2021
Electromagnetic shielding is one of the compulsory preventions to restrain external EMI leakage onto electronic devices and suppress the radiation of internal EMI to the environment. An ideal protection against EMI could be gained by placing electronic devices into a shielding enclosure made from high conductivity material without any aperture on itself. Yet, apertures are necessary practically for various reasons such as mounting connectors, power cables or heat dissipation. Those apertures reduce the shielding performance by permitting EMI to pass inside the enclosure. Shielding effectiveness (SE) indicates the EMI shielding performance of the enclosure, which is defined as a ratio of field strengths in the presence and absence of the enclosure (Mendez 1978; Robinson et al. 1998; Yenikaya 2009).