Antenna device
An antenna device which includes a plurality of antennas in a common case and is capable of achieving downsizing while suppressing a decrease of an antenna gain, is provided. An antenna device includes a TEL antenna and a capacity loaded element in a common case. The capacity loaded element is located above the TEL antenna. A length of the capacity loaded element is a positive integer multiple of one-half a wavelength of a PCS band. The TEL antenna is arranged so as to avoid a voltage maximum point of a standing wave, of the PCS band, generated in the capacity loaded element.
1. An antenna device for a vehicle comprising:
a common case; and
a first antenna and a second antenna which are provided in the common case,
wherein the second antenna has a plate shape and is located above the first antenna,
wherein a whole length of the second antenna is an odd multiple of one-half of a wavelength of a frequency band of the first antenna,
wherein a center position of the first antenna in a front-rear direction of the first antenna is located within one-eighth of a wavelength from a voltage minimum point of a standing wave that is generated in the second antenna between ends of the whole length of the second antenna by the frequency band of the first antenna,
wherein at least a part of the first antenna overlaps at least a part of the second antenna when viewed from a right-left direction of the antenna device, and
wherein the frequency band of the first antenna is higher than a frequency band of the second antenna.
2. The antenna device according to claim 1 , wherein the second antenna has a first plate-shaped part located above the first antenna,
wherein the first antenna is located below a center part of the first plate-shaped part,
wherein an electrical length of the first plate-shaped part is an odd multiple of one-half a wavelength of the frequency band of the first antenna.
3. The antenna device according to claim 1 , wherein the second antenna has a first plate-shaped part located above the first antenna, and a second plate-shaped part electrically connected to the first plate-shaped part through a filter part that cuts off the frequency band of the first antenna.
4. The antenna device according to claim 3 , wherein the first plate-shaped part and the second plate-shaped part are arranged with the first plate-shaped part separated from the second plate-shaped part in a above the first antenna, and a second plate-shaped part electrically connected to the first plate-shaped part through the filter part that cuts off the frequency band of the first antenna.
5. The antenna device according to claim 1 , wherein in the second antenna, at least a portion located above the first antenna is divided in a right-left direction.
6. The antenna device according to claim 1 , further comprising a helical element electrically connected to the second antenna.
7. The antenna device according to claim 6 , wherein the helical element is wound helically and elliptically when viewed from a winding axis direction of the helical element.
8. The antenna device according to claim 1 , further comprising a base that defines a storage space of the first and second antennas together with the case,
wherein the first antenna has a portion vertical to the base.
9. The antenna device according to claim 1 , wherein the first antenna is a TEL antenna, a TV antenna, a keyless entry antenna, an inter-vehicle communication antenna or a WiFi antenna, and the second antenna is an AM/FM antenna or a DAB receiving antenna.
10. The antenna device according to claim 1 , wherein the second antenna has a first plate-shaped part located above the first antenna, and
wherein the first antenna is located below a center part of the first plate-shaped part of the second antenna.
11. The antenna device according to claim 1 , wherein the second antenna has a first plate-shaped part located above the first antenna, and a second plate-shaped part electrically connected to the first plate-shaped part through a meander line.
12. The antenna device according to claim 11 , wherein the first plate-shaped part and the second plate-shaped part are arranged with the first plate-shaped part separated from the second plate-shaped part in a front-rear direction.