Importance

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Abstract

A transponder for, for example, domestic animals can receive high frequency energy and transmit information of an antenna (L.sub.x, L.sub.y, L.sub.z) and has a storage capacitor (C.sub.5) for storing received energy, which is used for transmitting on the antenna. In order to make the antenna less sensitive to the geometric direction of the received high frequency energy, it has a plurality of antenna coils (L.sub.x, L.sub.y, L.sub.z), that are arranged in an angle to each other, e.g. perpendicularly to each other. Monitoring circuits (LD.sub.x, LD.sub.y, LD.sub.z, 1) can detect the energy received on each coil and compare the detected values to each other and can, for issuing information, use that coil on which the largest energy has been received. Thereby, the transmission can be made in a direction which is considerably more optimal than a direction which otherwise would be obtained in a more random fashion. Each antenna portion is further included in an oscillatory circuit having two different natural frequencies. Thereby information of the transponder can be issued by modulating between these frequencies, what produces a transmission that is more free from interference compared to the case where only one frequency is used with on/off-modulation.

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First Claim