An electronic device and a method for manufacturing an outer housing of the electronic device are provided. The electronic device includes an outer housing including a portion including a base including a non-conductive material and a plurality of islands formed on or above the base, wherein the plurality of islands include metallic materials, wherein the plurality of islands are spaced apart from each other, and wherein the plurality of islands form a two-dimensional (2D) pattern. The method includes injection-molding a base and forming a plurality of islands on or above the base, wherein the plurality of islands include metallic materials, and wherein the plurality of islands are spaced apart from each other to form a 2D pattern.