| 摘要 |
<P>PROBLEM TO BE SOLVED: To suitably receive and process a reflected wave signal by a reflected wave reader in a form of plural transmissions whose communication distances are different from each other, in spite of the distance attenuation of the reflection wave signal. <P>SOLUTION: According to a transmission form of a reflector; an angle, a position of an antenna, and a power amplification of a non-modulated carrier wave in a transmitter, are controlled. Either in a proximity communication or a short-range communication, a suitable communication environment is constructed by dynamically changing an antenna directivity and a transmission power level. Alternatively, antennas respectively specific for the vicinity communication and the close range communication may be provided, the antennas to be used may be switched over, and the transmission power level may be switched over according to the antenna to be used. <P>COPYRIGHT: (C)2007,JPO&INPIT |
