부산대학교 도서관

The advances in information communication have increased the usage of microwaves in the 0.5–5 GHz range because of the demand for the transmission of large amounts of data. Accordingly, the problem of electromagnetic interference has become increasingly serious, and therefore much attention has been paid to microwave absorbers to solve the problem. Thin microwave absorbers are required with high values of relative complex permeability (μr = μr′ + jμr″) and permittivity (ɛr = ɛr′ + jɛr″). In this study various permalloy alloys with high permeability were designed, melted in a high-frequency induction furnace in air, melt-dragged into flakes, crushed into powders by a vibration mill, and deformed into ultrathin flakes by an attrition mill. The flake powders were then mixed with silicone rubber and formed into a sheet. When the flakes were mixed with the silicone rubber and formed into a 1 mm thick sheet the complex permeability and complex permittivity were substantially increased and the reflection loss at 0.8 GHz was –2.13 dB. It is possible to make thin and high-performance microwave-absorbing sheets with a flake powder of 79Ni–Fe alloy. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)