| 摘要 |
<p>A communications apparatus, such as a portable radiotelephone, comprises a housing (40) containing a printed circuit board (PCB) (12) having a ground plane (16) and electronic components in rf shields (18) thereon. A planar antenna (10), for example a planar inverted-L antenna (PILA), is mounted spaced from the ground plane and a dielectric (14), for example, air, is present in a space between the PCB and the planar antenna. A feed (36) couples the planar antenna (10) to the rf components. The feed comprises parallel L-C resonator circuit components (42), a transmission line, or any other predominantly reactive network for reactively tuning the antenna. In the case of a dual band antenna the components are selected so that a lower frequency is tuned inductively and a higher frequency is tuned capacitively. The components, which may be discrete or distributed, are mounted on the PCB or a part of the planar antenna structure which is not subject to detuning by the user in normal operation of the apparatus.</p> |
