An antenna assembly of reduced size but with optimized radiation and reception capabilities through slanted connections between the parts includes a feed portion, a first ground portion, a second ground portion, a first radiating portion, and a second radiating portion. The first radiating portion is a loop antenna on at least three surfaces of a carrier, and is connected between the feed portion and the first ground portion on opposite ends. The first radiating portion feeds in electric current through the feed portion. The second radiating portion is spaced from the first radiating portion, the second radiating portion is arranged on at least two surfaces of the carrier. The second radiating portion is connected between the second ground portion, the second radiating portion couples electric current from the first radiating portion. A wireless communication device employing the antenna assembly is also provided.