| 摘要 |
A variable resonant circuit is inserted between a feeding point of a radiating element and a ground conductor. When the variable resonant circuit is not inserted, an input impedance of the radiating element is lower than about 50Ω and capacitive in a first low frequency band, lower than about 50Ω and inductive in a second low frequency band, and close to about 50Ω in a high frequency band. When the variable resonant circuit exhibits a first resonance characteristic, the variable resonant circuit is inductive in the first low frequency band, and its impedance in the high frequency band is higher than that in the first low frequency band. When the variable resonant circuit exhibits a second resonance characteristic, the variable resonant circuit is capacitive in the second low frequency band, and its impedance in the high frequency band is higher than that in the second low frequency band. |
| 主权项 |
1. An antenna device comprising:
a radiating element that operates in a first low frequency band, a second low frequency band higher than the first low frequency band, and a high frequency band higher than the second low frequency band; a ground conductor; and a variable resonant circuit inserted between a feeding point of the radiating element and the ground conductor, and that switches between at least two resonance characteristics, a first resonance characteristic and a second resonance characteristic; wherein in an open state in which the variable resonant circuit is not inserted between the feeding point and the ground conductor, an input impedance of the radiating element is lower than about 50Ω and capacitive in the first low frequency band, lower than about 50Ω and inductive in the second low frequency band, and closer to about 50Ω in the high frequency band than the input impedances in the first low frequency band and the second low frequency band are; when the variable resonant circuit exhibits the first resonance characteristic, the variable resonant circuit is inductive in the first low frequency band, and an impedance of the variable resonant circuit in the high frequency band is higher than an impedance of the variable resonant circuit in the first low frequency band; and when the variable resonant circuit exhibits the second resonance characteristic, the variable resonant circuit is capacitive in the second low frequency band, and an impedance of the variable resonant circuit in the high frequency band is higher than an impedance of the variable resonant circuit in the second low frequency band. |
