Radio frequency transponder with improved read distance

摘要

A radio frequency identification transponder (RFID tag) in accordance with the principles of the present invention includes a tag antenna and RFID circuitry having respective input impedances Za and ZL. In accordance with the principles of the invention, the read distance of the RFID tag is maximized by connecting an inductor in series between the antenna and the RFID tag circuitry. The inductor having an impedance ZL that maximizes the expression [(Ra)(Ga)]½|(ZL|/|Za+Zind+ZL|, where | | indicates the absolute value of the enclosed expression.