A UHF near-field rfid reader antenna with reconfigurable recognition area

Abstract

The invention discloses a UHF near-field RFID reader antenna with reconfigurable identification area, which includes a medium plate and a metal layer. The metal layer is etched on the upper surface of the dielectric plate and consists of two dipole arrays with the same structure and arranged in a collinear manner. Dipole arrays are all composed of a feed unit and a parasitic unit, and the feed unit includes two arms of equal length; the parasitic unit is slightly shorter than the feed unit. Adjust the distance between the parasitic unit and the feeding unit to form a reverse current pair, generate a strong and relatively uniform magnetic field in a large area of ​​the near field of the antenna, and identify the near field label in this area. Based on the superposition principle, the two dipole arrays placed in collinear and fed in equal phase can enhance the near-field magnetic field strength in the middle area. By adjusting the spacing of the dipole arrays, the near-field magnetic field can be made uniform and the identification area of ​​the antenna can be expanded. ; By adjusting the feeding phase difference of the two dipole arrays, the reconfiguration of the identification area is realized.

Description

technical field [0001] The invention belongs to the technical field of electromagnetic fields and microwaves, and in particular relates to a UHF near-field RFID reader antenna with a reconfigurable identification area. Background technique [0002] The near-field radio frequency identification (RFID) system is based on magnetic field coupling and works in the low frequency (LF) or high frequency (HF) frequency band, which is not easily affected by the environment where the tag is located, but its identification distance is affected by The far-field RFID system generally adopts the ultra high frequency (Ultra High Frequency, UHF) or microwave (MicroWave, MW) frequency band, which has a high reading rate and a long recognition distance, but is easily affected by the environment of the reader tag. Combining the advantages of the near and far field, the researchers proposed the UHF near field RFID system, which is widely used in the retail industry, logistics warehousing and pha...

AI Technical Summary

Problems solved by technology

[0003] For the traditional loop reader antenna, when it works in the UHF frequency band, the current on the loop reverses, resulting in the generation of identification blind spots, which greatly reduces the identification area. Therefore, how to expand the identification area is a research in recent years. hotspot

Generally speaking, there are three methods as follows: one is to segment the electrically large-sized loop antenna, and load lumped or distributed capacitance between the segments to realize the same direction of loop surface current; the other is to use two or four even The poles are combined into a circular ring or a square ring, and the dipoles are fed with equal phases to achieve the same current direction; the above two methods can expand the area of ​​​​the identification area, but are still limited by the perimeter size of the loop antenna , it is difficult to further expand the identification area; the third is to construct reverse current pairs to enhance the near-field magnetic field between the reverse current pairs. This method has a simple structure, but the identification area is small

The identification area of ​​the reader antenna based on the above three methods is difficult to further expand, and the fixed area does not have reconfigurability

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