A communication device, comprising: a ground element; and an antenna system, adjacent to the ground element, wherein the antenna system at least comprises: a first antenna (11, 41, 71); a second antenna (12, 42, 72), adjacent to the first antenna (11, 41, 71); a connection element (14, 44, 54, 64, 74), comprising a first portion (141, 441, 541, 641, 741) and a second portion (142, 442, 542, 642, 742), wherein the first portion (141, 441, 541, 641, 741) is coupled to the first antenna (11, 41, 71), and the second portion (142, 442, 542, 642, 742) is coupled to the second antenna (12, 42, 72); and a resistive element, coupled between the first portion (141, 441, 541, 641, 741) and the second portion (142, 442, 542, 642, 742) of the connection element (14, 44, 54, 64, 74), wherein the connection element (14, 44, 54, 64, 74) and the resistive element increase isolation between the first antenna (11, 41, 71) and the second antenna (12, 42, 72); wherein the first antenna (11, 41, 71) further comprises a first feeding element coupled to a first signal source, and a first shorted element coupled to the ground element, wherein the second antenna (12, 42, 72) further comprises a second feeding element coupled to a second signal source, and a second shorted element coupled to the ground element, and characterized in that the connection element (14, 44, 54, 64, 74) is coupled between the first feeding element and the second shorted element. a ground element; and an antenna system, adjacent to the ground element, wherein the antenna system at least comprises: a first antenna (11, 41, 71); a second antenna (12, 42, 72), adjacent to the first antenna (11, 41, 71); a connection element (14, 44, 54, 64, 74), comprising a first portion (141, 441, 541, 641, 741) and a second portion (142, 442, 542, 642, 742), wherein the first portion (141, 441, 541, 641, 741) is coupled to the first antenna (11, 41, 71), and the second portion (142, 442, 542, 642, 742) is coupled to the second antenna (12, 42, 72); and a resistive element, coupled between the first portion (141, 441, 541, 641, 741) and the second portion (142, 442, 542, 642, 742) of the connection element (14, 44, 54, 64, 74), wherein the connection element (14, 44, 54, 64, 74) and the resistive element increase isolation between the first antenna (11, 41, 71) and the second antenna (12, 42, 72); wherein the first antenna (11, 41, 71) further comprises a first feeding element coupled to a first signal source, and a first shorted element coupled to the ground element, wherein the second antenna (12, 42, 72) further comprises a second feeding element coupled to a second signal source, and a second shorted element coupled to the ground element, and characterized in that the connection element (14, 44, 54, 64, 74) is coupled between the first feeding element and the second shorted element. a first antenna (11, 41, 71); a second antenna (12, 42, 72), adjacent to the first antenna (11, 41, 71); a connection element (14, 44, 54, 64, 74), comprising a first portion (141, 441, 541, 641, 741) and a second portion (142, 442, 542, 642, 742), wherein the first portion (141, 441, 541, 641, 741) is coupled to the first antenna (11, 41, 71), and the second portion (142, 442, 542, 642, 742) is coupled to the second antenna (12, 42, 72); and a resistive element, coupled between the first portion (141, 441, 541, 641, 741) and the second portion (142, 442, 542, 642, 742) of the connection element (14, 44, 54, 64, 74), wherein the connection element (14, 44, 54, 64, 74) and the resistive element increase isolation between the first antenna (11, 41, 71) and the second antenna (12, 42, 72); wherein the first antenna (11, 41, 71) further comprises a first feeding element coupled to a first signal source, and a first shorted element coupled to the ground element, wherein the second antenna (12, 42, 72) further comprises a second feeding element coupled to a second signal source, and a second shorted element coupled to the ground element, and characterized in that the connection element (14, 44, 54, 64, 74) is coupled between the first feeding element and the second shorted element.