Antenna device
An antenna device includes a ground conductor; a ground conductor extension that is connected to the ground conductor; and an antenna element that is connected to the ground conductor and that operates in both a first frequency band and a second frequency band higher than the first frequency band, the ground conductor and the ground conductor extension having a length that is ¼ of a wavelength of a frequency included in a middle range between the first frequency band and the second frequency band and that is not a natural number multiple of ¼ of a wavelength of the first frequency band.
1. An antenna device comprising:
a ground conductor;
a ground conductor extension that is connected to the ground conductor; and
an antenna element that is connected to the ground conductor and that operates in both a first frequency band and a second frequency band higher than the first frequency band, wherein
a total length of the ground conductor and the ground conductor extension is within a range from −5% to +20% of a quarter wavelength of a first frequency, wherein the first frequency is included in a middle frequency range between the first frequency band and the second frequency band, and the total length of the ground conductor and the ground conductor extension is not a natural number multiple of a quarter wavelength of a second frequency included in the first frequency band.
2. The antenna device according to claim 1 , wherein
the total length of the ground conductor and the ground conductor extension is equal to the quarter wavelength of the first frequency.
3. The antenna device according to claim 1 , wherein
the ground conductor has a substantially rectangular shape;
the antenna device further comprises:
a feeder disposed at an end of a first side of the ground conductor; and
a connector disposed at an end closer to the feeder among ends of a second side of the ground conductor opposite to the first side; and
the ground conductor is connected to the ground conductor extension via the connector.
4. The antenna device according to claim 1 , wherein
the first frequency band is a 800 MHz band; and
the second frequency band is a 2 GHz band.
5. The antenna device according to claim 1 , wherein
the ground conductor is contained in a first portion;
the ground conductor extension is contained in a second portion; and
the antenna element is contained in a third portion;
wherein
the first portion, the second portion, and the third portion are defined as a portions of the antenna device.
6. The antenna device according to claim 1 , wherein
the antenna element has a first antenna element that operates in the first frequency band and a second antenna element that operates in the second frequency band;
the first antenna element is a meander-shaped element; and
the second antenna element is an inverted L-shaped element.
7. The antenna device according to claim 5 , further comprising:
a main body of a wristwatch-type terminal;
a first belt that is connected to the main body and that is made of a resin; and
a second belt that is connected to the main body on a side opposite to the first belt and that is made of a resin;
the first portion being the main body,
the second portion being the first belt, and
the third portion being the second belt.
8. The antenna device according to claim 7 wherein
the ground conductor extension in the first belt has a substantially triangular shape, wherein one side of the triangular-shaped ground conductor extension is arranged in a direction of extension of the first belt.