A mobile device, at least including a metal housing, being substantially a hollow structure, wherein the metal housing has a back region and at least one side region, a first slit, formed on the metal housing, a dielectric substrate, comprising at least a first protruded portion, a first connection element, positioned between the metal housing and the dielectric substrate, and electrically coupled to the metal housing and a first signal source, positioned inside and electrically coupled to the metal housing, wherein at least one portion of the metal housing is configured to receive and transmit at least one wireless signal.