Antenna

1. An antenna, disposed on a first substrate and a second substrate, comprising:

a feeding portion disposed on a first surface of the first substrate for feeding electromagnetic signals; and

a radiating portion electronically connected to the feeding portion for transceiving the electromagnetic signals, comprising:

a first radiator disposed on the first surface of the first substrate and electronically connected to the feeding portion;

a second radiator disposed on a second surface of the second substrate; and

a third radiator comprising a first cylinder portion and a second cylinder portion electronically connected to the first cylinder portion, the first cylinder portion and the second cylinder portion being electronically connected to the first radiator and the second radiator, respectively, wherein a radius of the first cylinder portion is bigger than that of the second cylinder portion, and the first cylinder portion and the second cylinder portion co-form a metal spring thimble.

2. The antenna as recited in claim 1 , wherein the first surface of the first substrate faces the second surface of the second substrate.

3. The antenna as recited in claim 1 , wherein the first radiator comprises a first rectangle-shaped portion, an S-shaped portion, and an L-shaped portion connected in sequence, the rectangle-shaped portion is electronically connected to the first cylinder portion, and the L-shaped portion is electronically connected to the feeding portion.

4. The antenna as recited in claim 3 , wherein the second radiator comprises a second rectangle-shaped portion and an n-shaped portion connected to the second rectangle-shaped portion, and the rectangle-shaped portion is electronically connected to the second cylinder portion.

5. The antenna as recited in claim 1 , wherein the second radiator and the third radiator can be connected and disconnected flexibly.

6. A wireless local area network (WLAN) antenna, comprising:

a feeding portion disposed on a first plane for feeding electromagnetic signals; and

a radiating portion electronically connected to the feeding portion for transceiving electromagnetic signals, comprising:

a first radiator disposed on the first plane, and connected to the feeding portion;

a second radiator disposed on a second plane, wherein the first plane is paralleled to the second plane; and

a third radiator being a spring thimble formed by two cylinder portions with different radius, and resiliently connecting the first radiator to the second radiator.

7. The WLAN antenna as recited in claim 6 , wherein the second radiator and the third radiator are disconnectable.

8. An antenna assembly comprising:

a first substrate defining a first plane;

a second substrate spaced from said first substrate and at least one part of said second substrate overlapping said first substrate along a direction intersecting both of said first and second substrates, said second substrate defining a second plane facing said first plane; and

an antenna disposed on said first and second planes, said antenna comprising a feeding portion disposed on said first plane for feeding electromagnetic signals, and a radiating portion electrically connectable with said feeding portion for transceiving electromagnetic signals, said radiating portion comprising a first radiator disposed on said first plane to electrically connect with said feeding portion, a second radiator disposed on said second plane, and a third radiator disposed between said first and second planes to electrically connect with said first radiator and said second radiator respectively;

wherein said third radiator is a spring thimble formed by two cylinder portions with different radius.

9. The antenna assembly as recited in claim 8 , wherein said first and second radiators respectively comprise a rectangle-shaped portion wider than other portions thereof to electrically connect with said third radiator.