In detecting reception signals of RFID multi-tag,
reflection and intervention of signals may cause
errors seriously. As well, locations of tags should be
in straight line to polarization plane as possible as can
be and locations and directionality of tag antennas are
not free enough. To obtain high recognition rate that
minimizes errors that may be caused by multichannel
signals and is not affected by the direction of
tag antenna, this study designed UHF RFID reader
antenna using a circular polarization wave.