| 摘要 |
PROBLEM TO BE SOLVED: To provide an antenna device which is small and in which broad banding is possible, and to provide wireless communications equipment. SOLUTION: The antenna device 1 is provided with a radiation electrode 2, a radiation electrode 3, a switch 4 and a reactance circuit 5-1. The radiation electrode 2 has a U-shape and is connected to a power feeding part 110. The radiation electrode 3 is disposed inside the radiation electrode 2 and extends, in parallel with an opposite portion 22 of the radiation electrode 2 in close proximity. A distributed constant-type capacitance C is formed between the radiation electrodes 2 and 3 to capacitively couple the radiation electrodes 2 and 3. The switch 4 is an element for electrically connecting or disconnecting the radiation electrode 3 to/from the radiation electrode 2, and the reactance circuit 5-1 is loaded between the switch 4 and the radiation electrode 3, to change the electrical length of the antenna device 1 and consequently, the antenna device 1 resonates at a single-resonance frequency f0, when the switch 4 is off, and is in a double-resonance state of resonance frequencies f1 and f2, when the switch is switched on. COPYRIGHT: (C)2010,JPO&INPIT
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