ANTENNA FOR READER/WRITER AND READER/WRITER HAVING THE ANTENNA

摘要

An antenna comprises a soft magnetic member (5) and a conductive member (7). The soft magnetic member (5) is provided between an antenna coil (4) of one or more turns and a metal surface (6) of a conductive article such as a metal case on which the antenna is disposed, made of a composite material of an organic material and one of a metal granular powder, a metal flaky powder, and a granular powder of a ferrite, a ferrite, an amorphous foil, or a multilayer body of an amorphous foil, and having a thickness of 10 mm or less or a thickness satisfying a predetermined relation between the antenna area, the periphery length, and the permeability. The conductive member (7) has a resistivity of about 10 x 10-8 Ωm or less, preferably about 3 x 10-8 Ωm or less and a resistance of about 0.015 Ω or less, preferably about 0.005 Ω or less. The soft magnetic member (5) and the conductive member (7) block the magnetic flux entering the conductive article and suppress the influence. Thus an antenna used for a reader/writer of an RFID system and adapted to suppress the variation of the resonance frequency and the increase of the loss even if the antenna is disposed in contact with a conductive article such as a metal case.