High Data Capacity Chipless RFID Tag Based on Time-Domain Scattering Modulation

In this communication, we present a low-cost chipless radio frequency identification (RFID) tag with a high data capacity and a wide reading range based on time-domain scattering modulation. The proposed tag consists of a slotted square patch antenna with a switchable resistor and a mechanically driven slider etched with a barcode-like metallic wire array. Encoding is achieved by the presence and absence of the metallic wire on the slider, and tag identification is obtained by sequential bit reading. A special encoding strategy is applied to improve its insensitivity to the motion velocity of the slider. For a proof-of-concept demonstration, a prototype designed to operate at 2.1 GHz was fabricated and measured, and the experimental results verified the effectiveness. Compared with the methods based on time-domain reflectometry, spectral signature, and resonator-based sequential encoding, the proposed approach provides a substantially enhanced data capacity within a narrow spectrum without sacrificing its reading range and tag size, due to the design of nonresonant code cell. Such a mechanically triggered chipless RFID tag exhibits promising potentials in some practical applications, such as personal ID and credit cards.