A method of making a patch antenna includes the steps of: stamping a first metal plate to form a first plate body, a first aperture and a first protruding portion to thereby form a radiation metal layer; stamping a second metal plate to form a second plate body, a second aperture and a second protruding portion to thereby form a grounding metal layer; placing the metal layers in a mold to couple together the first and second protruding portions; and introducing an insulation material into the mold to form a dielectric layer between the metal layers.