Near-Field Chipless-RFID System Based on Hybrid Time/Frequency Domain Encoding and Power Splitter Reader
Amirhossein Karami‐Horestani, Ferran Paredes, Ferran Martı́n
Abstract
In this paper, a novel time/frequency domain near-field chipless-RFID system based on tags implemented by means of a set of linear strips, and a power splitter reader is proposed for the first time. The tags consist of two parallel chains of strips transversely oriented, and the size (length) of the strips varies between 4 different values, corresponding to 4 states and, hence, to 2 bits of information. Thus, each (predefined) strip position of the chain pair, provides 4 bits, and, consequently, the per-unit length data density, a relevant figure of merit in near-field chipless-RFID systems, can be enhanced significantly. For tag reading, the tag is displaced at short distance over the reader, a T-junction power splitter operating in stop-band configuration. The proposed system encodes the information in frequency, as far as the four different strips of the tag provide four different stop bands, centred at different frequencies, when such strips lie on top of the output arms of the splitter. However, the pair of bits of each chain corresponding to a predefined position of the strips is read sequentially, in a time-division multiplexing scheme, and, therefore, the proposed system is a hybrid time/frequency domain chipless-RFID system. For tag reading, the power splitter must be fed by four harmonic signals, corresponding to the central frequencies of the stop bands generated by the strips. In this paper, a proof-of concept demonstrator of this novel approach is presented.