| 摘要 |
A communication device is presented that has an antenna structure with a relatively short length and covers multiple resonances including the UHF and the GPS bands. The antenna structure has a conductive base to which a whip antenna is connected through a helical radiating element. A cylindrical sheath capacitively connected to the helical element provides distributed impedance matching for the antenna structure. A monopole or another helical element provides higher resonance than that of the whip antenna or connected helical element. If the higher resonance is provided by a monopole, the monopole is disposed radially adjacent to the helical element and is capacitively connected with the helical element through an opening in the sheath. If the higher resonance is provided by a helical element, the helical element is capacitively or galvanically connected to the end of the whip antenna.
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