| 摘要 |
PURPOSE:To miniaturize the antenna itself and to reduce its cost by providing plural antenna elements, using plural antenna elements at the time when a frequency is low, and using one antenna element at the time when the frequency is high. CONSTITUTION:One frequency of a two frequency antenna and the other frequency are denoted as f1 and f2, respectively. An antenna element 1 has dimensions for resonating to f1 and with respect to f1, the impedance Z becomes the impedance which becomes large enough. Accordingly, in them case of f1, the device is not influenced by an antenna element 2 and in the case of f1, it executes the same operation as only the antenna element 1 is installed. Also, in the case of f2, when the impedance Z is set so as to become a sufficient low value, the device operates as the antenna element being in a state that the elements 1, 2 in f2 are added. That is, the impedance Z is set so that the elements 1, 2 are operated simultaneously by a lower frequency in two frequencies, and only the element 1 is operated by a higher frequency. In such a way, a multi-frequency can be obtained. |
