An electronic device includes a display, and a housing at least partially surrounding the display and comprising a first housing member defining a first portion of an exterior surface of the electronic device and a second housing member defining a second portion of the exterior surface of the electronic device and configured to function as an antenna. The electronic device also includes a joining structure positioned between the first housing member and the second housing member including a reinforcement plate and a molded element at least partially encapsulating the reinforcement plate and engaged with the first housing member and the second housing member, thereby retaining the first housing member to the second housing member.