To facilitate maintenance work with less manufacture and installation costs and without taking an installation place by arranging an antenna means so that a prescribed communication possible area is formed on routes at an entrance and an exit by one antenna means.
A reader/writer 101 is arranged in the center of an entrance 106 and an exit 107 in a parking lot and the communication possible areas 103 and 104 of an antenna part 102 belonging to the reader/writer 101 are formed on the entering routes of the entrance 106 and the exit 107 by only one antenna. An antenna part 201 is formed of a solenoid coil and the solenoid coil forms a plane. Thus, electromagnetic fields (communication possible areas 103 and 104) that the solenoid coil generates are formed in right/left with the plane as a symmetrical face. Since the antenna part 201 is arranged in the center of the entrance 106 ad the exit 107, the right/left communication possible areas 103 and 104 are formed on the entering routes of the entrance 106 and the exit 107 and entering/leaving at the entrance/exit can be managed by using only one antenna part 102.
INOUE KOJI
KUSAKA TAKUYA
KOBAYASHI MINORU
