Multi-Resonator Structure for Small Size Chipless Radio Frequency Identification Tag

Abstract

The recent growth in identification, tracking, and sensing applications for the Internet of Things (IoT) has pushed the RFID technology to gain much attention due to its remarkable advantages compared to conventional identification techniques. New resonator structure for chipless RFID tags is proposed. The proposed tag consists of three resonators arranged in a compact form, vertically polarized receiving antenna and horizontally polarized transmitting antenna. Two resonators are based on spiral type and the third is a simple transmission line configured in compact shape. The two antennas are designed to be wide band and orthogonally polarized for realizing the cross polarization retransmission process. The tag provides eight different codes in the range from 2.2 to 2.5 GHz. The prototype resonator structure of the tag is designed and fabricated on RT Duroid 5880 substrate (with a dielectric constant 2.2, loss tangent 0.0009 and thickness 0.79 mm). Area saving in the order of 30% with respect to conventional spiral resonator can be achieved. Good agreement between simulated and measured results is observed.