Patent ID: 7256697

Claim:
A radio frequency IC tag including an IC chip for storing information and an antenna of a microstrip structure for transmitting wirelessly the information stored on the IC chip, the radio frequency IC tag comprising: an antenna substrate, on a first surface of which the IC chip is mounted at a substantial center of the first surface, and which has a ground pattern formed over a remainder of the first surface and electrically connected to a first electrode terminal of the IC chip, the antenna substrate having a predetermined dielectric constant; an antenna radiation portion mounted on a second surface of the antenna substrate and electrically connected to a second electrode terminal of the IC chip; and a metallic outer casing accommodating therein the antenna substrate and the antenna radiation portion, wherein a height of the antenna radiation portion is set to a value greater than a machining margin, and wherein said ground pattern is formed within the metallic outer casing, and separated from the metallic outer casing by a predetermined space.