Abstract-There is increasing interest in electromagnetic interference (EMI) shielding due to the serious electromagnetic environment pollution caused by the continuously increased use of the electrical products and electronic devices. Electrical conductivity and EMI shielding effectiveness (SE) of composite materials made from silicone rubber with carbon powder and ferrite powder have been studied in microwaves and terahertz frequency ranges and the results are presented in this paper. In microwaves range, samples with higher electrical conductivity show a small variation of shielding performance with frequency, whereas the performance of samples with lower conductivity falls away with increasing frequency. It is shown that the variation of attenuation with frequency relates to the conductivity of the material.
The character of the original paper is to provide electromagnetic radiation absorbing material that attenuation characteristics of the electromagnetic field very good, as compared to the absorbent materials studied to date. This paper presents results of research on processing, characterization and behavior of composite materials based on silicone rubber used for electromagnetic shielding. In this work silicone rubbers is reinforced with magnetic fillers (iron silicon). The obtaining of composite materials was with the aid of a doctor blade technique. Doctor blade technique is a coating technique widely used for producing thin films on large area surfaces. The samples were processed in the laboratory using a plated nettling (PN), that was impregnated with a silicone rubber based composite containing powder of iron silicon (SI). Were achieved measurements of the both parts of the materials obtaining. These have shown an electromagnetic shielding effectiveness the order of 3.35-41.62 dB (white face) and 3.53-41.42 dB (gray face), in 1-18 GHz frequency range according to SR EN 50 147-1:1999. The paper tries to identify an absorbent material with the ability to protect human beings of electromagnetic radiation that surround us every day and every moment. With the exponential increase in development of commercial, aerospace, military and scientific electronic devices in modern society, electromagnetic radiation is becoming the fourth public pollution after the air, water and noise ones.
The RF circuits are difficult to be miniaturized without compromises concerning the technical performances. The inductors and antennas are the major constraints for systems miniaturization, due to the lack of magnetic materials with adequate high frequency properties. The paper presents novel Co-based magnetic nanostructured materials, with improved characteristics which recommend them as potential candidates for transformers and inductors in electronic components: higher level for saturation magnetisation and electric resistivity in comparison with commercial ferrites. The magnetic nanocomposites are prepared by sol-gel route and consist on Co magnetic nanocrystallites, arranged in a crystalline matrix (silicates, for example). The main physical characteristics of the Co/SiO2 nanopowders are developed after appropriate calcination and annealing, being dependent on the SiO2 amount and on the thermal treatment parameters: saturation magnetisation Ms = 81.7 – 130.4 emu/g, coercivity Hc = 21.7 – 26.9 kA/m (273 - 338 Oe) and increased resistivities for the sintered samples, due to the presence of the SiO2 layers.
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