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The Double PEC Wedge Problem: Diffraction and Total Far Field
摘要： Complex scattering targets are often made by structures constituted of wedges that may interact at near field. In this paper, we examine the scattering of a plane electromagnetic wave by two separated arbitrarily oriented perfectly electrically conducting wedges with parallel axes. The procedure to obtain the solution is based on the recently developed semianalytical method known as generalized Wiener–Hopf technique that allows a comprehensive mathematical model of the problem in the spectral domain avoiding multiple steps of interaction among separated objects. The numerical results are presented to validate the procedure in terms of spectral quantities, GTD/uniform theory of diffraction coefficients and total far fields for engineering applications. The structure is of interest in electromagnetic applications, in particular, to accurately predict path loss in propagation with diffraction phenomena.
关键词： electromagnetic diffraction,radar applications,wedges,propagation,electromagnetic shielding,wireless communication,Wiener–Hopf (WH) method,integral equations,EMC,near-field interactions,Antenna technologies
更新于2025-09-23 15:21:01
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Electromagnetic and acoustic double-shielding graphene-based metastructures
摘要： Nowadays, acoustic and electromagnetic pollution problems are becoming increasingly serious. Thus, electromagnetic interference (EMI) shielding materials and high acoustic insulation materials are urgently needed. EMI shielding materials and high acoustic insulation materials or structures have been rapidly developed. However, electromagnetic yet acoustic shielding (double-shielding) structures have not been reported so far. Herein, we propose a novel metastructure based on a graphene paper and artificial honeycomb, which exhibits not only excellent electromagnetic interference shielding property but also robust acoustic shielding efficiency. The EMI shielding effectiveness of the metastructure is up to 74 dB in a broad range from 2.6 to 26.5 GHz. The acoustic shielding effectiveness reaches 25 dB from 200 to 1500 Hz. It is worth noting that the effectiveness of acoustic shielding reaches up to 40 dB at very low frequency of 200 Hz. A typical double-shielding application demo was assembled to prove the attenuation performance against electromagnetic waves and sound. Our unique metastructure is very promising for protecting from electromagnetic and acoustic pollution.
关键词： graphene,double-shielding,acoustic shielding,electromagnetic shielding,metastructure
更新于2025-09-19 17:15:36
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Novel conducting PVA/Carbon quantum dots (CQDs) nanocomposite for high anti-electromagnetic wave performance
摘要： Novel conductive PVA/CQDs nanocomposite films were synthesized through the casting technique for the electromagnetic (EM) wave protection at microwave band. The surface morphology, thermal and mechanical properties were briefly studied. The SEM micrograph showed an excellent distribution, dispersion and a high adhesion property of the CQDs in the PVA chains. Also, DSC analysis showed an increase in the glass temperature (Tglass) from 83.2 °C for fresh PVA to 95.4 °C for 8 wt% of CQD and the increase in melting temperature from 215 °C for fresh PVA to 227.7 °C for the same CQDs concentration. It was found that Young's modulus is directly proportional to CQD nano-particles concentration in the nano-composites from 0.14 GPa for fresh PVA to 4.48 GPa for 8 wt% of CQDs. It was found that the strength at break increases, but the elongation declines with the increase of CQDs nano-particles. The EM shielding effectiveness (SE) of (PVA/CQDs) nanocomposite is measured in the microwave frequency range, and it is found around 36.8 dB with the CQDs concentration (8 wt%). Finally, the PVA/CQDs nano-composite is of promising potential applications in electronics and microwave devices at an affordable cost.
关键词： PVA,Mechanical properties,Electromagnetic shielding,Thermal properties,CQDs nano-particles
更新于2025-09-19 17:13:59