Design of Chipless RFID Tag for Products Identification

Abstract

Chipless radio frequency identification (CRFID) is a rapidly growing technology in the RFID system that uses electromagnetic (EM) waves for its operation. The exclusion of expensive silicon IC chip from the tag results in a cost-effective, low-weight, conformable, and compact chipless RFID tag. The frequency-domain chipless tags work on the backscattering principle in which a transmitted wave reflects from a metallic chipless tag and its radar cross-section (RCS) computed. The RCS contains encoded information about the tag in question. Several CRFID tags have been proposed to cope with challenges such as bit capacity, code density, spectral efficiency, thickness, and angular stability. However, there isn‘t any thin tag to date that has all these features simultaneously. In this research work, two frequency domain-based chipless RFID tags are proposed to overcome the demands and requirements of the RFID market. The first design presents a unique 32-bit chipless RFID tag operating in a 4.5 - 10.9 GHz frequency band. The tag has a multiple-arc type shape consisting of closely packed wide arcs of different radii and lengths. The specific tag geometry provides multiple resonances in the frequency domain of an RCS plot. A frequency-domain coding technique has also been proposed to encode the tag‘s RCS signature into a digital identification code. The proposed tag is built on a thin substrate with an overall dimension of 17.5 × 17.5 mm 2 , resulting in a high code density of 10.44 bits/cm2 and spectral efficiency of 5 bits/GHz. The RCS response of the tag is stable for up to 70°. The second design presents a novel structural design methodology for miniaturized chipless RFID tags in the frequency domain. The tag geometry is developed by loading an open loop resonator with micro-metallic cells (MMC). The realization gives rise to a checkerboard resonator type with electromagnetic signatures in its radar cross-section that is extremely efficient to manipulate. The resonator‘s layout is distributed on either side of a substrate to double its coding density. The proposed chipless RFID tag has a memory of 8-bits. The operating frequency band of a tag is 6.5 - 10.5 GHz. The tag has a high code density of 10.94 bits/cm2 and spectral efficiency of 2 bits/GHz. The RCS response of the tag is stable for up to ±45°. The tag has a compact size of 17.4 × 4.2 mm2 and can thus be utilized in various modern identification scenarios