| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a radio tag reader which has good precision of direction detection of a radio tag. <P>SOLUTION: Correlation errors between electric power intensity patterns and a reference pattern are calculated respectively from radio waves from respective antennas 412, 414, and 416 of a radio tag 400 (S108). The reference pattern is an electric power intensity pattern when a vertical polarized wave is received in an ideal environment on sequential switching of directivity by an antenna part 1. Correlation errors Γ between the reference pattern and received electric power intensity patterns of the radio waves received from the respective antennas 412, 414, and 416 have large values when the received radio waves principally comprise horizontal polarized waves. An electric power intensity pattern having a minimum correlation error Γ is selected as a pattern for direction estimation, so the selected pattern may be a pattern when the radio wave principally comprising the vertical polarized waves are received with high possibility. Direction detection of the radio tag 400 can be therefore performed with high precision. <P>COPYRIGHT: (C)2013,JPO&INPIT |
