Importance

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Abstract

An antenna circuit to be used in conjunction with a chip transponder such that the antenna circuit serves for both the reception of interrogative signals intended for the transponder as well as for response signals that ape to be transmitted by the transponder. The antenna circuit has at least one magnetic circuit of high .mu. material, and is formed of ceramic core means, that have been built into a depression in a thick-walled surface intended to receive the chip transponder. This thick-walled surface may be of metal. The ceramic core means comprise at least a ceramic core resonator and half a ceramic core that functions as an antenna with its open side facing outward. In one aspect, the ceramic core resonator and the half ceramic core antenna are coupled by means of one or more secondary coils of the closed ceramic core, which also form the coils of the half ceramic core antenna. In another aspect, the secondary coil forms a resonating circuit with at least one capacitive element in series. In yet another aspect, the ceramic core resonator and the half ceramic core antenna are formed by one and the same half ceramic core, which may be closed in part by a magnetic covering disk. In yet another aspect, the resonator may consist of a half ceramic core which is placed against the back of the half ceramic core antenna.

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First Claim