Mobile device

A mobile device, comprising:

• a metal back cover, having a slot;
• a dielectric substrate, having a first surface and a second surface opposite to the first surface, wherein the second surface of the dielectric substrate faces the slot;
• a grounding metal element, coupled to the metal back cover, and extending onto the first surface of the dielectric substrate;
• a first radiation element, having a feeding point, and disposed on the first surface of the dielectric substrate, wherein the first radiation element has a first vertical projection on the metal back cover, the first vertical projection at least partially overlaps the slot, and a coupling gap is formed between the first radiation element and the grounding metal element;
• and
• a second radiation element, disposed on the second surface of the dielectric substrate, wherein the second radiation element has a second vertical projection on the metal back cover, and the second vertical projection at least partially overlaps the slot;
• wherein an antenna structure is formed by the first radiation element, the second radiation element, and the slot of the metal back cover.