Mobile device

1. A mobile device, comprising:

a ground element;

a metal frame;

a feeding connection element, coupled to a positive feeding point;

a first radiation element, coupled to the feeding connection element;

a second radiation element, comprising a first portion and a second portion, wherein the feeding connection element is coupled through the second radiation element to a first connection point on the metal frame;

a capacitive element, coupled between the first portion and the second portion;

a first shorting element, wherein a second connection point on the metal frame is coupled through the first shorting element to a first grounding point on the ground element;

a second shorting element, wherein a third connection point on the metal frame is coupled through the second shorting element to a second grounding point on the ground element; and

a third shorting element, wherein a fourth connection point on the metal frame is coupled through the third shorting element to a third grounding point on the ground element;

wherein an antenna structure is formed by the ground element, the metal frame, the feeding connection element, the first radiation element, the second radiation element, the capacitive element, the first shorting element, and the second shorting element;

wherein a positive electrode of a signal source is coupled to the positive feeding point, and a negative electrode of the signal source is coupled to a negative feeding point on the ground element, so as to excite the antenna structure.

2. The mobile device as claimed in claim 1 , wherein at least a portion of the metal frame substantially has an L-shape.

3. The mobile device as claimed in claim 1 , wherein the first radiation element substantially has a straight-line shape.

4. The mobile device as claimed in claim 1 , wherein the second radiation element substantially has an L-shape.

5. The mobile device as claimed in claim 1 , further comprising:

a parasitic element, coupled to a fourth grounding point on the ground element, wherein the parasitic element is adjacent to the first radiation element.

6. The mobile device as claimed in claim 5 , wherein the parasitic element substantially has an L-shape.

7. The mobile device as claimed in claim 1 , wherein the antenna structure covers a first frequency band at 1575 MHz, a second frequency band from 2400 MHz to 2500 MHz, and a third frequency band from 5100 MHz to 5850 MHz.

8. The mobile device as claimed in claim 7 , wherein an inverted F-shaped resonant path is formed by the feeding connection element, the first radiation element, the second radiation element, the capacitive element, the metal frame, and the second shorting element, and wherein the inverted F-shaped resonant path is excited to generate the first frequency band.

9. The mobile device as claimed in claim 7 , wherein a first loop resonant path is formed by the feeding connection element, the second radiation element, the metal frame, the first shorting element, and the ground element, and wherein the first loop resonant path is excited to generate the second frequency band.

10. The mobile device as claimed in claim 7 , wherein a second loop resonant path is formed by the feeding connection element, the second radiation element, the metal frame, the second shorting element, and the ground element, and wherein the second loop resonant path is excited to generate the third frequency band.