Patent ID: 8339321

Claim:
An antenna device, comprising: a first antenna element that has a resonance characteristic in a first frequency; a second antenna element that has a resonance characteristic in a second frequency and is spaced from the first antenna element at a predetermined distance; a wireless circuit section that supplies or receives high-frequency power; and a switch section that selectively connects an output terminal or an input terminal of the wireless circuit section and a feeding point of the first antenna element or the second antenna element, so as to switch and connect the wireless circuit section and either one of the first antenna element and the second antenna element, wherein the second antenna element has an antenna effective length made shorter than an antenna effective length of the first antenna element, and when the switch section connects the wireless circuit section and the feeding point of the second antenna element and power is transmitted or received from the second antenna, the first antenna element operates as a passive element of the second antenna element, whereby the frequency characteristic of the second antenna element has a resonance characteristic in a vicinity of the second frequency and a third frequency higher than the second frequency.