Communication device

1. A communication device, comprising:

an antenna system, comprising a first dual-polarized antenna and a first reflector, wherein the first reflector is configured to reflect radiation energy from the first dual-polarized antenna;

a metal base; and

a metal elevating pillar, coupled between the antenna system and the metal base, and configured to support the antenna system;

wherein a distance between the first reflector and the first dual-polarized antenna is slightly longer than 0.25 wavelength of an operation frequency band,

wherein a bottom surface of the antenna system has a circumscribed circle with a first radius, the metal base has a circular shape with a second radius, and a height of the metal elevating pillar is linearly related to a ratio of the second radius to the first radius;

wherein the height of the metal elevating pillar is calculated according to the following equation:

H

=

0.75

×

λ

0

×

(

RB

RA

-

1

)

wherein H represents the height of the metal elevating pillar, λ 0 represents a free-space wavelength of an operation frequency band of the antenna system, RA represents the first radius, and RB represents the second radius.

2. The communication device as claimed in claim 1 , wherein the first reflector has a pyramidal shape with a wide top opening and a narrow bottom plate, and the wide top opening of the first reflector faces the first dual-polarized antenna.

3. The communication device as claimed in claim 2 , wherein the wide top opening of the first reflector has a relatively large square shape, and the narrow bottom plate of the first reflector has a relatively small square shape.

4. The communication device as claimed in claim 1 , wherein the first dual-polarized antenna comprises a first dipole antenna element and a second dipole antenna element, and the first dipole antenna element and the second dipole antenna element are perpendicular to each other.

5. The communication device as claimed in claim 4 , wherein the first dipole antenna element and the second dipole antenna element are diamond-shaped dipole antenna elements.

6. The communication device as claimed in claim 1 , wherein the first dual-polarized antenna covers the operation frequency band from 1850 MHz to 2690 MHz.

7. The communication device as claimed in claim 4 , wherein the antenna system further comprises a first metal plate for balancing radiation gain of the first dipole antenna element and the second dipole antenna element, and the first dual-polarized antenna is positioned between the first metal plate and the first reflector.

8. The communication device as claimed in claim 7 , wherein the first metal plate has a square shape, a circular shape, or an equilateral triangular shape.

9. The communication device as claimed in claim 7 , wherein a length or a width of the first metal plate is shorter than 0.5 wavelength of an operation frequency band of the first dual-polarized antenna.

10. The communication device as claimed in claim 1 , wherein the antenna system further comprises a second dual-polarized antenna and a second reflector, the second reflector is configured to reflect radiation energy from the second dual-polarized antenna, and the second dual-polarized antenna is disposed opposite to or adjacent to the first dual-polarized antenna.

11. The communication device as claimed in claim 10 , wherein the antenna system further comprises a second metal plate, and the second dual-polarized antenna is positioned between the second metal plate and the second reflector.

12. The communication device as claimed in claim 10 , wherein the antenna system further comprises a third dual-polarized antenna, a fourth dual-polarized antenna, a third reflector, and a fourth reflector, the third reflector is configured to reflect radiation energy from the third dual-polarized antenna, and the fourth reflector is configured to reflect radiation energy from the fourth dual-polarized antenna.

13. The communication device as claimed in claim 12 , wherein the antenna system further comprises a third metal plate and a fourth metal plate, the third dual-polarized antenna is positioned between the third metal plate and the third reflector, and the fourth dual-polarized antenna is positioned between the fourth metal plate and the fourth reflector.

14. The communication device as claimed in claim 12 , wherein the first dual-polarized antenna, the second dual-polarized antenna, the third dual-polarized antenna, and the fourth dual-polarized antenna are arranged symmetrically with respect to their central point, and each of them covers a 90-degree spatial angle.

15. The communication device as claimed in claim 12 , wherein the antenna system is a beam switching antenna assembly for selectively using one of the first dual-polarized antenna, the second dual-polarized antenna, the third dual-polarized antenna, and the fourth dual-polarized antenna to perform signal reception and transmission.

16. The communication device as claimed in claim 1 , wherein a top area of the metal elevating pillar is the same as a bottom area of the antenna system.