process for the production of a flat, flexible antennenkerns for a chip transponder installed in a card or similar object and such a law antennenkern

摘要

An antenna core is of a material having a high quality factor, wherein an elongated strip of mutually insulated, longitudinally stretched chains of magnetic soft material of high mu is formed. In one aspect a powder of small particles of a magnetic soft material of high mu is mixed with a synthetic resin so that a high saturation of magnetic material in the mixture is formed in a vacuum. The mixture is cured in the shape of a block while being in a strong static magnetic field and the particles form persistent chains parallel to the applied magnetic field. The block is cut into thin strips following a longitudinal direction which corresponds to the direction of the previously applied magnetic field, each such strip making up an antenna core. In another aspect said chains are formed of thin wires of magnetic soft iron covered with an insulating layer. These wires are formed into a flat bundle-shaped strip, such strip making up an antenna core. In yet another aspect said elongated strips are formed of an amorphous alloy, in which the longitudinal direction coincides with the direction of magnetic field, said strips being mutually insulated. A stack is formed of one or more of these strips, such stack making up an antenna core. A flat flexible antenna is obtained by forming an electrical winding around one or more of the above mentioned strip- or stack-shaped antenna cores. IMAGE