HIGH-FREQUENCY MAGNETIC CORE MATERIAL, ITS MANUFACTURING METHOD, AND ANTENNA WITH THE MAGNETIC CORE MATERIAL

摘要

[PROBLEMS] A magnetic core material having a high magnetic permeability in a specific direction, favorable in dimensional precision, and hard to break, especially a high-frequency magnetic core material operating in the VHF to UHF bands, its manufacturing method, and an RFID tag with the magnetic core material or an antenna for reader/writers. [MEANS FOR SOLVING PROBLEMS] A content of about 10 to 50%, preferably about 10 to 40%, by volume of a soft magnetic metal powder having a particle size below a predetermined particle size (about 1 mum) is kneaded with plastic or rubber. This material is subjected to expansion in one direction of a compound material such as extruding rolling, rolling after extruding, drawing after extruding, or rolling after injecting. Consequently, the magnetic permeability can be high and dependent on direction. The dimensional precision can be high and the material is hard to break. An RFID tag and an antenna for reader/writers can be fabricated by providing an antenna pattern on one side of this magnetic core material and a conductive material on the other. Thus, an antenna hardly leaking the magnetic flux and having a high performance can be fabricated.