| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a variable directional antenna device which can obtain excellent directivity without being affected by surrounding walls. <P>SOLUTION: A storage part 65 of a direction detection device composed of variable directional antennas has stored therein a reactance value set per directivity consisting of reactance values respectively corresponding to each variable reactance element, at which time two kinds of sets, one for the case where there is a wall at the back and one for the case where there is no wall at the back, are stored as a per-directivity reactance value set. A variable reactance control unit 61, with directivity directed toward a rear surface direction, calculates a power ratio of transmitted power to received power. This power ratio is large when there is a wall at the back and small when there is no wall at the back. Therefore, the power ratio and a threshold value X are compared to determine whether there is a wall at the back. Then, based on the determination result, either one of two sets stored in the storage part 65 is selected to set a reactance value. <P>COPYRIGHT: (C)2012,JPO&INPIT</p> |
