Alnico Magnet 전파흡수체와 Al2 O3의 코팅에 의한 각종 전파흡수체의 전파흡수능 향상에 관한 연구

Abstract

By the progress of electronics and radio communication technology, humans enjoy greater freedom in communicating. However, EM(electromagnetic) wave environments have become complicated and more difficult to control. Accordingly, international organizations such as the ANSI (American National Standard Institution), FCC (Federal Communications Commission), and CISPR (the Comite Internationale Special des Perturbations Radio electrique), etc provided standard for the EM wave environments and for the countermeasure of the EM compatibility (EMC).

EM wave absorbers are used for countermeasure against EMC from electronic protect electronic devices, such as personal communications and wireless LAN systems from unwanted EM wave radiations. When we consider the problem of the natural environment and resources, it is a good way to use recycled magnet. In addition to develope a more advanced EM wave absorbers, it is important to develop new materials, while soft and hard magnetic materials, such as Mn-Zn, Ni-Zn, Ba, and Sr ferrites are well-known ones.

In this thesis, the EM wave absorption with Alnico magnets, and compared EM wave absorption properties were compared between cast Alnico magnets, which have different magnetic properties. Alnico magnet has magnetic properties of Br=0.65 T, Hc=45 kA/m, and (BH)max=11 kJ/m3, and Alnico magnet has magnetic properties of Br=0.87 T, Hc=125 kA/m, and (BH)max=45 kJ/m3. Furthermore, the coating effects were investigated AlO for MnZn ferrite, Ba ferrite, Sr ferrite, and Alnico magnets.