Multi-band antenna

1. A multi-band antenna, comprising:

a radiating portion;

a ground portion; and

a coaxial transmission line;

wherein the radiating portion, the ground portion and the coaxial transmission line cooperatively form a plurality of antennas meeting at a common junction, said plurality of antennas being coplanar with each other and being all fed by the same coaxial transmission line, the multi-band antenna is formed of a metallic sheet by defining a plurality of holes therein.

2. The multi-band antenna as claimed in claim 1 , wherein one of the plurality of holes is inverted-L shaped.

3. The multi-band antenna as claimed in claim 1 , wherein the radiating portion comprises a first radiating portion, a second radiating portion and a third radiating portion.

4. The multi-band antenna as claimed in claim 1 , wherein the radiating portion comprises a first section connecting the radiating portion with the ground portion.

5. The multi-band antenna as claimed in claim 1 , wherein the plurality of antennas comprises a first inverted-F antenna, a second inverted-F antenna and a loop antenna.

6. The multi-band antenna as claimed in claim 5 , wherein the first inverted-F antenna and the loop antenna are operated at a higher frequency band, while the second inverted-F antenna is operated at a lower frequency band, the first inverted-F antenna and the loop antenna operating at the same frequency band.

7. The multi-band antenna as claimed in claim 5 , wherein the first inverted-F antenna and the loop antenna are respectively operated at different higher frequency bands, while the second inverted-F antenna is operated at a lower frequency band.

8. A multi-band antenna, comprising:

a first antenna having a first radiating portion;

a second antenna having a second radiating portion;

a third antenna having a third radiating portion; and

a feeder;

wherein said first, second and third antennas have a common ground portion and a collective feeder, and said first, second and third radiating portions are connected with each other, the second and the third radiating portions define an inverted-L shaped slit therebetween.

9. The multi-band antenna as claimed in claim 8 , wherein the second and the third radiating portions are arranged above the first radiating portion.

10. The multi-band antenna as claimed in claim 8 , wherein the first antenna is a loop antenna.

11. The multi-band antenna as claimed in claim 8 , wherein the second antenna is an inverted-F antenna.

12. The multi-band antenna as claimed in claim 8 , wherein the third antenna is an inverted-F antenna.

13. The multi-band antenna as claimed in claim 8 , wherein the first radiating portion and the ground portion define an inverted-L shaped space therebetween.

14. The multi-band antenna as claimed in claim 8 , wherein the third radiating portion is L-shaped and defines a longer signal path than the second radiating portion.

15. The multi-band antenna as claimed in claim 8 , wherein the second and the third radiating portions essentially form as a rectangular shape in structure.

16. The multi-band antenna as claimed in claim 8 , wherein the first radiating portion comprises a first section connecting the second and the third radiating portions with the ground portion.

17. A multi-band antenna comprising:

a common ground portion;

a first radiation section extending from an upward edge of the ground portion;

essentially parallel spaced second and third radiation section joined at a distal end of the first radiation section, said radiation section being closer to the ground portion than the third radiation section; and

a feeder cable including an outer connected to the ground portion and an inner conductor connected to the second radiation section.

18. The multi-band antenna as claimed 17 , wherein said first radiation section is of a downwardly lying L-shaped configuration.