Antenna system with planar dipole antennas and electronic apparatus having the same

1. An antenna system comprising:

an antenna module including

a substrate including opposite first and second surfaces, and

a plurality of planar dipole antennas disposed on said first surface of said substrate, each of said planar dipole antennas including

a short-circuit section that has a grounding segment and two sides,

a pair of first radiator sections that are operable in a first frequency band and that are connected electrically and respectively to said two sides of said short-circuit section, and

a pair of second radiator sections that are operable in a second frequency band, each of said second radiator sections having a feed-in portion and an extending portion, said feed-in portion being connected electrically to said short-circuit section and having a distal end distal from said short-circuit section, said extending portion extending from said distal end of said feed-in portion of the respective one of said second radiator sections, one of said second radiator sections of each of said planar dipole antennas having a feed-in segment, said planar dipole antennas being arranged such that geometric centers of said planar dipole antennas are respectively spaced apart from a center point bounded by said planar dipole antennas by a predetermined distance, such that each of said planar dipole antennas is spaced apart from an adjacent one of said planar dipole antennas by a predetermined minimum distance, and such that, for each of said planar dipole antennas, said feed-in segment, said grounding segment, and said center point are disposed on a same line; and

a system module having a grounding plane that faces toward and that is spaced apart from and parallel to said second surface of said substrate.

2. The antenna system as claimed in claim 1 , wherein, for each of said planar dipole antennas, said first radiator sections extend in an extending direction, said short-circuit section extends substantially parallel to the extending direction and is disposed on a first side of said first radiator sections, and said extending portions of said second radiator sections extend substantially parallel to the extending direction and are disposed on a second side of said first radiator sections opposite to said first side.

3. The antenna system as claimed in claim 2 , wherein, for each of said planar dipole antennas, said feed-in segment is disposed on said feed-in portion of said one of said second radiator sections.

4. The antenna system as claimed in claim 2 , wherein, for each of said planar dipole antennas, said short-circuit section further extends substantially perpendicular to the line on which said center point, said feed-in segment and said grounding segment are disposed.

5. The antenna system as claimed in claim 2 , wherein said short-circuit section of said planar dipole antenna has one side flush with said first side of said first radiator sections.

6. The antenna system as claimed in claim 1 , wherein said planar dipole antennas are symmetrically arranged about said center point and along respective peripheral sides of said substrate.

7. The antenna system as claimed in claim 6 , wherein each of extending lines extending respectively from said geometric centers of said planar dipole antennas to said center point forms a predetermined angle with an adjacent one of said extending lines.

8. The antenna system as claimed in claim 7 , wherein said antenna module includes three of said planar dipole antennas, and the predetermined angle is 120 degrees.

9. The antenna system as claimed in claim 1 , wherein, for each of said planar dipole antennas, said feed-in portions of said second radiator sections are spaced apart from each other by a first gap, said feed-in segment and said grounding segment are spaced apart from each other by a second gap, and said first and second gaps are in spatial communication with each other.

10. The antenna system as claimed in claim 1 , wherein, for each of said second radiator sections of each of said planar dipole antennas, said extending portion has a first end connected electrically to said distal end of said feed-in portion, and a second end distal from said distal end of said feed-in portion, said extending portion further having a width that increases gradually from one of said first and second ends to the other of said first and second ends.

11. The antenna system as claimed in claim 10 , wherein said second end of said extending portion is wider than said first end of said extending portion.

12. The antenna system as claimed in claim 1 , wherein said substrate is formed with a through hole that coincides with said center point so as to permit extension of signal-feed cables therethrough.

13. The antenna system as claimed in claim 1 , wherein said substrate occupies an area not larger than that occupied by said system module.

14. The antenna system as claimed in claim 1 , wherein said substrate is made of a dielectric material.

15. The antenna system as claimed in claim 1 , wherein said system module is a system circuit board.

16. The antenna system as claimed in claim 1 , wherein said grounding plane of said system module is disposed such that said grounding plane of said system module is able to reflect radiation from said antenna module.

17. An electronic apparatus comprising a housing, and an antenna module and a system module disposed in said housing,

said antenna module including

a substrate including opposite first and second surfaces, and

a plurality of planar dipole antennas disposed on said first surface of said substrate, each of said planar dipole antennas including

a short-circuit section that has a grounding segment and two sides,

a pair of first radiator sections that are operable in a first frequency band and that are connected electrically and respectively to said two sides of said short-circuit section, and

a pair of second radiator sections that are operable in a second frequency band, each of said second radiator sections having a feed-in portion and an extending portion, said feed-in portion being connected electrically to said short-circuit section and having a distal end distal from said short-circuit section, said extending portion extending from said distal end of said feed-in portion of the respective one of said second radiator sections, one of said second radiator sections of each of said planar dipole antennas having a feed-in segment, said planar dipole antennas being arranged such that geometric centers of said planar dipole antennas are respectively spaced apart from a center point bounded by said planar dipole antennas by a predetermined distance, such that each of said planar dipole antennas is spaced apart from an adjacent one of said planar dipole antennas by a predetermined minimum distance, and such that, for each of said planar dipole antennas, said feed-in segment, said grounding segment, and said center point are disposed on a same line,

said system module having a grounding plane that faces toward and that is spaced apart from and parallel to said second surface of said substrate.

18. The electronic apparatus as claimed in claim 17 , wherein said antenna module and said system module are spaced apart from each other so as to enable disposing of various electronic components therebetween.

19. The electronic apparatus as claimed in claim 17 , wherein said electronic apparatus is an access point.

20. The electronic apparatus as claimed in claim 17 , wherein said grounding plane of said system module is disposed such that said grounding plane of said system module is able to reflect radiation from said antenna module.