Novel UHF RFID Near-Field Reader Antenna with Uniform Vertical Electric Field Distribution

Yanbin Chen,Xin Chen,Xiaodong Chen,Jimin Zhao,Xiaojuan Ren,Yuan Yao,Junsheng Yu

doi:10.1155/2020/6078402

Abstract

This paper presents two novel UHF RFID near-field reader antennas with uniform vertical electric field distribution. The two antennas have the following common characteristics. First, the radiating parts of the two antennas are simulated and fabricated by the microstrip lines and work using the leakage wave principle of microstrip lines. Second, the end of microstrip lines match the load to form a traveling wave mode of operation, so the two antennas have broadband characteristics. Third, both antennas are fed in a coaxial manner at the center of the antenna. The simulation and measurement results can show that the proposed three-branch antenna and four-branch antenna achieve good impedance matching in the range of 883–960 MHz and 870–960 MHz, respectively, and achieve uniform distribution of the vertical electric field component in a certain area. The reading areas of the three-branch antenna and the four-branch antenna are 70 mm × 70 mm × 90 mm and 100 mm × 100 mm × 120 mm (length × width × height), respectively. Due to the introduction of the ground plate, the antenna gain is low, which meets the design requirements of near-field antennas.

Highlights

Radio frequency identification (RFID) is a wireless noncontact communication technology that uses radio frequency signals to identify specific targets and complete data exchange
One of the most important factors affecting the performance of an RFID system is the reader antenna, which determines its near-field or far-field application
In order to read linearly polarized tags arbitrarily placed in the reading area, it is required that the electric field generated by the reader antenna be uniform and controllable in three-dimensional space. e circularly polarized antenna [13, 14] can radiate and receive circularly polarized waves. e multipolarized near-field reader antenna [15] can provide a strong and uniform electric field distribution in the area to be read and has a low far-field gain

Summary

Introduction

Radio frequency identification (RFID) is a wireless noncontact communication technology that uses radio frequency signals to identify specific targets and complete data exchange. Large loop antennas can achieve uniform magnetic field distribution, they generally have high gain characteristics Another type of antenna with low gain characteristics can achieve the expandability of the reading area [12]. In order to read linearly polarized tags arbitrarily placed in the reading area, it is required that the electric field generated by the reader antenna be uniform and controllable in three-dimensional space. In order to achieve 100% reading of tags placed randomly in the reading area, the capacitively coupling RFID reader antenna needs to consider the uniformity of the electric field threedimensional component. We use the vertical space waves leaked by the microstrip lines to achieve uniform vertical electric field distribution of the two antennas. E current produces longitudinal space wave leakage along the symmetrical branches and achieves a uniform distribution of the electric field component perpendicular to the antenna surface The lateral leakage waves are cancelled out, weakening their influence on the longitudinal electric field distribution. e current produces longitudinal space wave leakage along the symmetrical branches and achieves a uniform distribution of the electric field component perpendicular to the antenna surface

Results and Discussion

Measured Simulated

Detected Undetected