Mobile communication device and antenna thereof

1. A mobile communication device having a ground plane and an antenna, wherein the antenna is disposed on a dielectric substrate, wherein the dielectric substrate has a first surface and a second surface opposite to the first surface, with a thickness defined between the first and second surfaces, with the antenna comprising:

a radiating metal portion located on the first surface, with the radiating metal portion being in a rectangular shape having a width and a length, wherein the width is at least one-eighth of the length, wherein an edge of the radiating metal portion faces the ground plane and has a distance between the edge and the ground plane, wherein the edge has a shorting point, wherein a central line of the radiating metal portion intersects the center of the length and is substantially perpendicular to the length, and wherein the distance between the shorting point and the central line of the radiating metal portion is less than 15 mm;

a coupling metal portion located on the second surface, with the coupling metal portion overlapping the rectangular shape of the radiating metal portion and coupling electromagnetic energy to the radiating metal portion via a coupling gap defined by the thickness, wherein the coupling metal portion is electrically connected to a source via a connecting metal strip substantially parallel to the central line, and wherein the distance between the connecting metal strip and the central line of the radiating metal portion is less than 15 mm; and

a shorting metal portion having one end electrically connected to the radiating metal portion and another end electrically connected to the ground plane, wherein the length of the shorting metal portion is at least 2 times of the distance between the radiating metal portion and the ground plane.

2. The mobile communication device as claimed in claim 1 , wherein a line width of the shorting metal portion of the antenna is less than 1 mm.

3. The mobile communication device as claimed in claim 1 , wherein the radiating metal portion of the antenna is bent at least once to protrude from the first surface to form a three-dimensional structure.

4. The mobile communication device as claimed in claim 1 , wherein operating bandwidths of the antenna cover 698˜960 MHz and 1710˜2170 MHz.

5. The mobile communication device as claimed in claim 1 , wherein the radiating metal portion comprises at least one slot spaced from and inside edges of the rectangular shape.

6. An antenna used in a mobile communication device having a ground plane, wherein the antenna is disposed on a dielectric substrate, wherein the dielectric substrate has a first surface and a second surface opposite to the first surface, with a thickness defined between the first and second surfaces, with the antenna comprising:

a radiating metal portion located on the first surface, with the radiating metal portion being in a rectangular shape having a width and a length, wherein the width is at least one-eighth of the length, wherein one edge of the radiating metal portion faces the ground plane and has a distance between the edge and the ground plane, wherein the edge has a shorting point, wherein a central line of the radiating metal portion intersects the center of the length and is substantially perpendicular to the length, and wherein the distance between the shorting point and the central line of the radiating metal portion is less than 15 mm;

a coupling metal portion located on the second surface, with the coupling metal portion overlapping the rectangular shape of the radiating metal portion and coupling electromagnetic energy to the radiating metal portion via a coupling gap defined by the thickness, wherein the coupling metal portion is electrically connected to a source via a connecting metal strip substantially parallel to the central line, and wherein the distance between the connecting metal strip and the central line of the radiating metal portion is less than 15 mm; and

a shorting metal portion having one end electrically connected to the radiating metal portion and another end electrically connected to the ground plane, wherein the length of the shorting metal portion is at least 2 times the distance between the radiating metal portion and the ground plane.

7. A mobile communication device having a ground plane and an antenna, wherein the antenna is disposed on a dielectric substrate, wherein the dielectric substrate has a first surface and a second surface opposite to the first surface, with a thickness defined between the first and second surfaces, with the antenna comprising:

a radiating metal portion located on the first surface, with the radiating metal portion being in a rectangular shape having a width and a length, wherein the width is at least one-eighth of the length, wherein an edge of the radiating metal portion faces the ground plane and has a distance between the edge and the ground plane, wherein the edge has a shorting point, wherein a central line of the radiating metal portion intersects the center of the length and is substantially perpendicular to the length, and wherein the distance between the shorting point and the central line of the radiating metal portion is less than 15 mm;

a coupling metal portion located on the second surface, with the coupling metal portion overlapping the rectangular shape of the radiating metal portion and coupling electromagnetic energy to the radiating metal portion via a coupling gap defined by the thickness, wherein the coupling metal portion is electrically connected to a source via a connecting metal strip substantially parallel to the central line, and wherein the distance between the connecting metal strip and the central line of the radiating metal portion is less than 15 mm; and

a shorting metal portion having one end electrically connected to the radiating metal portion and another end electrically connected to the ground plane, wherein the shorting metal portion is connected in series with a chip inductor.