| 摘要 |
<p>PURPOSE:To make it possible to adjust the detection range of a tag, by changing the antenna characteristics such as the directional pattern, and antenna gain of a characteristic variable antenna. CONSTITUTION:A tag detection apparatus A contains a horn antenna 3 and a receiving apparatus 4 and the antenna 3 is capable of adjusting the size of the aperture surface thereof and, therefore,the gain or directional pattern of the antenna 3 can be adjusted. The apparatus 3 detects the radio wave received by the antenna 3 to detect the presence of a tag 2. A moving body 1 is present in front of the antenna 3 and is transferred, for example, to a direction vertical to that of the apparatus A on a conveyer and the tag 2 is mounted to the surface of the moving body 1 in the side opposed to the apparatus A. This tag 2 oscillates a radio wave by the oscillator mounted therein or reflects the radio wave emitted from the apparatus A to emit the radio wave. By this method, the detection range of the tag can be adjusted.</p> |
