A three-dimensional slot antenna includes a loop conductor, a first conductor arm, a second conductor arm, and a third conductor arm. The first radiator section, the second radiator section and the third radiator section are disposed on a same plane. The second radiator section cooperates with the first and third radiator sections to form a first slot segment. The first radiator section further cooperates with the third radiator section to form a second slot segment. The first and second slot segments form a substantially T-shaped slot.