This invention constructs an antenna matching circuit able to avoid a bad influence when a conductor, such as a metal, or tag, approaches a reader/writer, and dissolves a communication defect area on the reader/writer and stably maintains a communication distance. In this invention, in a RFID system,...http://www.google.com/patents/US20050092836?utm_source=gb-gplus-sharePatent US20050092836 - Loop coilantenna
