To provide a communication device, a communication terminal, and a communication system, capable of simultaneously performing power transmission together with data communication in the same frequency band, performing data communication such as RFID, even during power transmission, and performing power transmission, according to the power volume required for operating a communication terminal even when there are a plurality of communication terminals requiring power transmission.
The communication device 100 is equipped with a first antenna 1 to transmit/receive electro-magnetic wave; a transmission-controlling circuit 6 to command power reception to the communication terminal 101; a DC/AC circuit 5 to convert a DC power from a power supply 2 to an AC power; a reception-control circuit 4 for modulating the amplitude of an AC wave output from the DC/AC circuit 5, according to the information of the power volume required for the communication terminal 101 to reply; and an impedance-detecting circuit 3 to detect the impedance value of the first antenna 1. The power transmission is simultaneously performed together with the data communication in the same frequency band by performing frequency modulation using the signal of the data communication in the transfer wave of the power transmission, and the intensity of the electromagnetic wave in the first antenna 1 is controlled according to the impedance value.
ONO YUJI
WAKAO NAOKI
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