Antenna device of mobile terminal

An antenna device of a mobile terminal, the antenna device comprising:

• an antenna module configured to radiate electric waves comprising:
• a body, which is an insulation material, and
• a radiation pattern functioning as a first radiator of electric waves, formed in the body toward a front surface of the mobile terminal to radiate electric waves toward the front surface in which a display screen of the mobile terminal is disposed;
• an internal case made of a first metal material, the internal case having a first slot in a portion of the first metal material and having a housing space for housing the antenna module;
• and
• an external case comprising a rear case formed at a rear surface of the mobile terminal opposite to the front surface of the mobile terminal in which the display screen of the mobile terminal is disposed, the external case made of a second metal material, having a housing space for housing the internal case, and having a second slot in a portion of the metal material,
• wherein the second slot is formed in the rear case, in alignment with the first slot of the internal case, and is electrically coupled to each of the radiation pattern of the antenna module and a ground of the mobile terminal such that the rear case is configured to function as a second radiator of electric waves resonating at frequency different of the radiation pattern of the antenna module and in a direction different from that of the radiation pattern of the antenna module.