Antenna device for vehicle
An antenna device for vehicle ( 10 A) includes an antenna base ( 100 ), an antenna case ( 600 ) forming an accommodation space together with the antenna base ( 100 ), a first monopole antenna ( 210 ) accommodated in the accommodation space, and a first parasitic element ( 300 ) provided above the first monopole antenna ( 210 ).
1. An antenna device for a vehicle, the antenna device comprising:
an antenna base;
an antenna case forming an accommodation space together with the antenna base;
a monopole antenna accommodated in the accommodation space; and
a parasitic element provided above the monopole antenna,
wherein the monopole antenna has a self-similar shape, and
wherein the monopole antenna is one of a plurality of the monopole antennas.
2. The antenna device according to claim 1 , wherein the parasitic element functions as a secondary radiating element.
3. The antenna device according to claim 1 , wherein the monopole antenna is a telematics antenna.
4. The antenna device according to claim 1 , wherein the parasitic element is constituted by a plurality of element parts spaced apart from each other.
5. The antenna device according to claim 1 , wherein the parasitic element functions as a part of a radio broadcast antenna.
6. The antenna device according to claim 1 , wherein a distance between an end portion of the parasitic element on a side of the monopole antenna and an end portion of the monopole antenna on a side of the parasitic element is λ/2−λ/4 or more and λ/2+λ/4 or less, where λ is a wavelength of a frequency of operating frequencies of the monopole antenna at which a gain is enhanced by the parasitic element.
7. The antenna device according to claim 1 , wherein the monopole antenna has a U-shape.
8. The antenna device according to claim 1 , further comprising an antenna including a capacitively-loaded element.
9. The antenna device according to claim 8 , wherein the parasitic element functions as a part of the antenna.
10. The antenna device according to claim 9 , wherein the parasitic element and the capacitively-loaded element are electrically connected through a filter.
11. The antenna device according to claim 1 , wherein the plurality of the monopole antennas includes a first monopole antenna and a second monopole antenna disposed in a front-rear direction.
12. The antenna device according to claim 11 , wherein a first part of the parasitic element is provided above the first monopole antenna and a second part of the parasitic element is provided above the second monopole antenna.
13. An antenna device for a vehicle, the antenna device comprising:
an antenna base;
an antenna case forming an accommodation space together with the antenna base;
a monopole antenna accommodated in the accommodation space; and
a parasitic element provided above the monopole antenna,
wherein the monopole antenna has a self-similar shape, and
wherein the parasitic element is constituted by a plurality of element parts spaced apart from each other.
14. The antenna device according to claim 13 , wherein the parasitic element functions as a secondary radiating element.
15. The antenna device according to claim 13 , wherein a distance between an end portion of the parasitic element on a side of the monopole antenna and an end portion of the monopole antenna on a side of the parasitic element is λ/2−λ/4 or more and λ/2+λ/4 or less, where λ is a wavelength of a frequency of operating frequencies of the monopole antenna at which a gain is enhanced by the parasitic element.
16. The antenna device according to claim 13 , wherein the monopole antenna has a U-shape.
17. The antenna device according to claim 13 , further comprising an antenna including a capacitively-loaded element.
18. An antenna device for a vehicle, the antenna device comprising:
an antenna base;
an antenna case forming an accommodation space together with the antenna base;
a monopole antenna accommodated in the accommodation space; and
a parasitic element provided above the monopole antenna,
wherein the monopole antenna has a self-similar shape, and
wherein the monopole antenna has a U-shape.
19. The antenna device according to claim 18 , wherein the parasitic element functions as a secondary radiating element.
20. The antenna device according to claim 18 , wherein a distance between an end portion of the parasitic element on a side of the monopole antenna and an end portion of the monopole antenna on a side of the parasitic element is λ/2−λ/4 or more and λ/2+λ/4 or less, where λ is a wavelength of a frequency of operating frequencies of the monopole antenna at which a gain is enhanced by the parasitic element.