| 摘要 |
The invention relates to double-action antenna structures. The structure comprises an antenna inside the covering of a mobile station, a switch (SW) and a whip element (240) movable in relation to the former two. The internal antenna comprises two elements the first of which (220) is connected to the feed conductor (202) of the whole antenna structure and the second to the signal ground (203, 210). When the whip element is retracted, the said switch galvanically interconnects the elements of the internal antenna. Thus only the internal antenna functions and the whip has no practical significance. When the whip element is extended, its lower end disconnects, by means of the switch, the elements of the internal antenna, and the whip element itself is connected in series with the first element. Thus, a radiating element is provided by the series connection (240, 220) of the whip and the first element, and the shorted element (230) of the internal antenna has no practical significance. The first element further provides for the matching of the whip element. The antenna structure may have one or more operating bands. In the structure according to the invention the length of the whip element may be chosen relatively freely because the electrical length of the structure can always be made suitable by means of the internal antenna element connected in series with the whip element. No mechanical parts or components are needed for the matching of the whip element.
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