| 摘要 |
A multiband antenna intended for small-sized radio devices, internal to the device. The antenna comprises a main element (320) connected to the antenna feed conductor (326) and a short-circuited parasitic element (330). The feed point (FP) is beside the short-circuit point (S1) of the parasitic element. The elements are typically elongated, and at least their parts, which correspond a certain operating band, are substantially perpendicular to each other. Two resonances, the frequencies of which fall on two different operating bands of the antenna, are excited also in the parasitic element. In order to implement the resonances of the parasitic element, the coupling between the elements takes place through a very narrow slot (309) near the feed point and the short-circuit point of the parasitic element. The coupling is then sufficiently strong in spite of the positions of the main and the parasitic element. Even the lower operating band of the antenna can be made so wide that it covers the frequency ranges of two different systems. |
