| 摘要 |
<p>The invention relates to an adjustable planar antenna especially applicable to mobile terminals, and to a radio device provided with that kind of antenna. The basic structure of the antenna is PIFA. On a surface of a dielectric part (205) there is placed a strip conductor (230) so that this has a significant electromagnetic coupling to the radiating plane (220). The strip conductor can be connected by a switch (SW) to the ground plane. When the switch is closed, the electric length of the radiating plane is changed, measured from the short point (S). In which case also the antenna's resonance frequency is changed. The change depends on the place and the size of the strip conductor. In the case of a multi-band antenna the strip conductor can be placed so that it has a remarkable electromagnetic coupling to one or more radiating elements (B1, 226). The adjusting of planar antenna is performed by means of small additive components, which do not presume changes in the antenna's basic structure and do not enlarge the antenna. <IMAGE></p> |
