| 摘要 |
An antenna intended for portable radio devices, which comprises a radiating slot in the ground plane of the radio device. This slot (220) is a functional main part of the antenna. It is located so that a relatively narrow strip of the ground plane remains between it and an edge of the ground plane (210). At the end of this ground strip (212), beside the open end of the slot, there is connected an elongated auxiliary element (230), which elevates slightly from the ground plane and is then directed toward the closed end of the slot. The auxiliary element increases the electric length of the slot so that the basic resonance frequency of the slot occurs in the range of the lower operating band of the antenna intended as a dualband antenna. The slot (220) thus functions as a radiator in the lower operating band. The antenna is fed from a point (FP) that is advantageous with regard to the matching, near the closed end of the slot. In addition, the auxiliary element (230) is dimensioned so that when the antenna is fed by the frequencies of the upper operating band, oscillation of its own is excited in the auxiliary element, in which case it functions as a radiator in the upper operating band. By means of the invention, also the lower operating band of a dualband antenna can be implemented by a structure that takes a relatively small amount of space, the antenna can be located advantageously with regard to SAR, and the matching of the antenna does not require separate matching components. |
