A mobile device, comprising: a main radiation element, having a first notch and a second notch, wherein the main radiation element comprises a feeding region configured to be coupled to a signal source and a grounding region configured to be coupled to a ground voltage; a parasitic radiation element, configured to be coupled to the ground voltage, wherein the parasitic radiation element is adjacent to the feeding region; and an additional radiation element, coupled to the main radiation element, wherein the additional radiation element and the parasitic radiation element substantially extend in a same direction; wherein an antenna structure is formed by the main radiation element, the parasitic radiation element and the additional radiation element; the main radiation element has a substantially rectangular shape with a first corner, a second corner, a third corner, and a fourth corner; a first current path is formed from the feeding region through the second corner and the first notch to the third corner; a second current path is formed from a second end of the additional radiation element through the second corner and the first notch to the third corner; the antenna structure covers a first frequency band from 2400MHz to 2500MHz, a second frequency band from 5100MHz to 5600MHz, and a third frequency band from 5600MHz to 5900MHz; a length of the first current path is substantially equal to 0.25 wavelength of the first frequency band; a length of the second current path is substantially equal to 0.5 wavelength of the second frequency band; and both the first current path and the second current path extend around the first notch; the second notch is arranged adjacent to the fourth corner; a length of the first notch is from 2mm to 4mm, and a width of the first notch is from 3mm to 5mm; and a length of the second notch is shorter than or equal to 10mm, and a width of the second notch is shorter than or equal to 2mm. a main radiation element, having a first notch and a second notch, wherein the main radiation element comprises a feeding region configured to be coupled to a signal source and a grounding region configured to be coupled to a ground voltage; a parasitic radiation element, configured to be coupled to the ground voltage, wherein the parasitic radiation element is adjacent to the feeding region; and an additional radiation element, coupled to the main radiation element, wherein the additional radiation element and the parasitic radiation element substantially extend in a same direction; wherein an antenna structure is formed by the main radiation element, the parasitic radiation element and the additional radiation element; the main radiation element has a substantially rectangular shape with a first corner, a second corner, a third corner, and a fourth corner; a first current path is formed from the feeding region through the second corner and the first notch to the third corner; a second current path is formed from a second end of the additional radiation element through the second corner and the first notch to the third corner; the antenna structure covers a first frequency band from 2400MHz to 2500MHz, a second frequency band from 5100MHz to 5600MHz, and a third frequency band from 5600MHz to 5900MHz; a length of the first current path is substantially equal to 0.25 wavelength of the first frequency band; a length of the second current path is substantially equal to 0.5 wavelength of the second frequency band; and both the first current path and the second current path extend around the first notch; the second notch is arranged adjacent to the fourth corner; a length of the first notch is from 2mm to 4mm, and a width of the first notch is from 3mm to 5mm; and a length of the second notch is shorter than or equal to 10mm, and a width of the second notch is shorter than or equal to 2mm.