Antenna device
An antenna device includes a dual-band cross dipole antenna including four radiators each extending from an axis toward a plane and including a first radiating element and a second radiating element for transmitting or receiving radio signals of a first band and a second band, wherein a plane where each radiator is located is perpendicular to a plane where a neighboring radiator is located; and a reflecting board disposed on a side of the dual-band cross dipole antenna, wherein a location and a shape of the reflecting board relate to wavelengths corresponding to signals of the first band and the second band, such that the dual-band cross dipole antenna is directional in the first band and omnidirectional in the second band.
1. An antenna device, comprising:
a dual-band crossed-dipole antenna, comprising four radiators each extending from an axis toward a plane and comprising a first radiating element and a second radiating element for respectively transmitting or receiving radio signals of a first band and a second band, wherein a plane where each radiator is located is perpendicular to a plane where a neighboring radiator is located; and
a reflecting board, disposed on a side of the dual-band crossed-dipole antenna;
wherein a first projection result generated by projecting the reflecting board along the central axis on a reference plane is substantially a square, and a second projection result generated by projecting the dual-band crossed-dipole antenna along the central axis on the reference plane is substantially corresponding to two diagonals of the square, wherein the reference plane is perpendicular to the central axis;
wherein a center frequency of the first band is higher than a center frequency of the second band, a diagonal length of the square of the first projection result is greater than 0.6 times of a signal wavelength corresponding to the first band and smaller than 0.35 times of a signal wavelength corresponding to the second band, a nearest distance between the reflecting board and any first radiating element of the four radiators is between 0.15 to 0.25 times of the signal wavelength corresponding to the first band, and the dual-band crossed-dipole antenna is substantially directional in the first band and omnidirectional in the second band.
2. The antenna device of claim 1 , wherein a cross section of the reflecting board comprises at least a bending.
3. The antenna device of claim 1 , wherein a cross section of the reflecting board comprises at least an arc segment.
4. The antenna device of claim 1 , wherein the reflecting board forms a cavity and the dual-band crossed-dipole antenna is disposed inside the cavity.
5. The antenna device of claim 1 , wherein each radiating element of the dual-band cross antenna comprises a director, for enhancing directivity of the dual-band crossed-dipole antenna on the first band.
6. The antenna device of claim 5 , wherein the director of each radiator is parallel to the second radiating element, and a distance between the director and the second radiating element is smaller than a distance between the director and the first radiating element.
7. The antenna device of claim 5 , wherein the director of each radiator extends on a first plane, and the first plane is identical to the plane extended by each radiating element.
8. The antenna device of claim 5 , wherein the director of each radiator extends on a first plane, and the first plane is not identical to the plane extended by each radiating element.
9. The antenna device of claim 5 , wherein a length of the director of each radiator is related to the first band.