Study of a Multi-Loop Travelling Wave UHF RFID Near-Field Antenna

Zijian Xing,Ziliang Li,Chow-Yen-Desmond Sim,Haotian Li,Jianying Li

doi:10.1109/access.2020.2985992

Abstract

A multi-loop travelling-wave ultra-high frequency (UHF) radio frequency identification (RFID) near-field antenna (NFA) is proposed and investigated. To achieve strong and uniform magnetic field, as well as extendable reading range, multiple λ/2 rectangular loop structures printed on both sides of an FR4 substrate is adopted. Via the RFID system measurement for magnetic field distribution, the maximum reading range of the proposed NFA is 11 cm, and its corresponding 100% reading rate distance is 5 cm. Here, broad 10-dB impedance bandwidth of 18.7% (816-984 MHz) was measured, which can cover both ETSI (European Telecommunication Standards Institute) and FCC (Federal Communications Commission) bands. Parametric studies are further carried out to facilitate the design and optimization processes.

Highlights

Radio frequency identification (RFID) has been a widely used non-contact automatic recognition technology for wireless identification and tracking ability
Typical RFID system includes reader, tag and post-processing system, and it is conventionally divided into far-field system (FFS) and nearfield system (NFS) based on operating distance [1]
For NFS that operates in the ultra-high frequency (UHF), it can provide higher data-rate and read-rate than those in high frequency (HF) or low frequency (LF) [2]

Summary

INTRODUCTION

Radio frequency identification (RFID) has been a widely used non-contact automatic recognition technology for wireless identification and tracking ability. NFA for near-field UHF RFID applications can be divided into three types, namely, loop antenna, oppositely directed currents (ODCs) structure antenna and travellingwave antenna. Because of the above design features, the proposed NFA can demonstrate both strong and uniform magnetic field distribution and broadband characteristic. This reported work is an extended version of the one reported in [27], in which our modified version has shown better impedance matching (VSWR 1.5 or return loss ≥14 dB) across the desired Universal UHF RFID band (840-960 MHz), and we have explicitly explained the design process and methodology. Extensive parametric studies are carried out to explore the operating mechanism of the proposed NFA, which provide useful information for antenna optimization

ANTENNA CONFIGURATION AND DISCUSSION

RECTANGULAR LOOP PERIMETER L

Findings

ANTENNA PERFORMANCES