Communication device

1. A communication device, comprising:

an antenna system, comprising:

a first dual-polarized antenna;

a first reflector, configured to reflect radiation energy from the first dual-polarized antenna;

a first PIFA (Planar Inverted F Antenna), separated from the first reflector; and

a first fork structure, positioned between the first reflector and the first PIFA, and coupled to the first reflector or the first PIFA.

2. The communication device as claimed in claim 1 , wherein the first PIFA covers a low-frequency band from 746 MHz to 894 MHz, and the first dual-polarized antenna covers a high-frequency band from 1710 MHz to 2360 MHz.

3. 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.

4. 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.

5. The communication device as claimed in claim 1 , wherein the first PIFA comprises a radiation element, a grounding element, and a feeding element, and wherein a slot is formed between the radiation element and the grounding element.

6. The communication device as claimed in claim 5 , wherein the feeding element extends across the slot and is coupled to the radiation element.

7. The communication device as claimed in claim 5 , wherein the slot substantially has an L-shape.

8. The communication device as claimed in claim 1 , wherein the first fork structure comprises a first branch element and a second branch element, and wherein both the first branch element and the second branch element are coupled to an edge of the first reflector or the first PIFA.

9. The communication device as claimed in claim 8 , wherein a length of the second branch element is equal to a length of the first branch element.

10. The communication device as claimed in claim 8 , wherein a combination of the first branch element and the second branch element substantially has an L-shape or an arc-shape.

11. The communication device as claimed in claim 8 , wherein an angle between the first branch element and the second branch element is from 70 to 110 degrees.

12. The communication device as claimed in claim 1 , wherein the first fork structure is a first double-fork structure which comprises a first portion and a second portion separated from each other, the first portion is coupled to an edge of the first reflector, and the second portion is coupled to the first PIFA.

13. The communication device as claimed in claim 1 , wherein the antenna system further comprises a second dual-polarized antenna, a second reflector, a second PIFA, and a second fork structure, the second reflector is configured to reflect radiation energy from the second dual-polarized antenna, the second PIFA is separated from the second reflector, and the second fork structure is positioned between the second reflector and the second PIFA, and is coupled to the second reflector or the second PIFA.

14. The communication device as claimed in claim 13 , wherein the antenna system further comprises a third dual-polarized antenna, a third reflector, a third PIFA, and a third fork structure, the third reflector is configured to reflect radiation energy from the third dual-polarized antenna, the third PIFA is separated from the third reflector, and the third fork structure is positioned between the third reflector and the third PIFA, and is coupled to the third reflector or the third PIFA.

15. The communication device as claimed in claim 14 , wherein the antenna system further comprises a fourth dual-polarized antenna, a fourth reflector, a fourth PIFA, and a fourth fork structure, the fourth reflector is configured to reflect radiation energy from the fourth dual-polarized antenna, the fourth PIFA is separated from the fourth reflector, and the fourth fork structure is positioned between the fourth reflector and the fourth PIFA, and is coupled to the fourth reflector or the fourth PIFA.

16. The communication device as claimed in claim 15 , 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.

17. The communication device as claimed in claim 15 , wherein the antenna system is a beam switching antenna assembly for selectively using any two 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.

18. The communication device as claimed in claim 15 , further comprising:

a metal elevating pillar, coupled to the first reflector, the second reflector, the third reflector, and the fourth reflector, wherein the metal elevating pillar is configured to support the antenna system.

19. The communication device as claimed in claim 15 , further comprising:

a top reflective plate, coupled to the first reflector, the second reflector, the third reflector, and the fourth reflector, wherein the top reflective plate is perpendicular to the first reflector, the second reflector, the third reflector, and the fourth reflector.

20. The communication device as claimed in claim 19 , further comprising:

a nonconductive antenna cover, having a hollow structure, wherein the antenna system and the top reflective plate are both disposed inside the nonconductive antenna cover.