Patent ID: 8059062
Filing Date: 2011-11-15
Classification: G06K,H01Q

Abstract:
1. An antenna circuit provided in a transponder that stores various readable and/or writable data and has a communication function, the antenna circuit comprising: a substrate; an antenna conductor including an antenna coil formed in a predetermined conductor pattern on a front surface of the substrate; a first sheet metal on a rear surface of the substrate opposed to the front surface of the substrate, the first sheet metal having a loop shape with a through hole, wherein a slit is provided in the first sheet metal that cuts off a part of the loop shape, the slit extending from the through hole to an outside edge of the first sheet metal, and the through hole is surrounded by the first sheet metal except where the slit is provided in the first sheet metal; and a second sheet metal disposed on an inner peripheral part of the first sheet metal with a minute gap between the first sheet metal and the second sheet metal, wherein the second sheet metal is electrically isolated from the first sheet metal.