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Ultrahigh frequency band near field RFID reader-writer antenna

A technology of ultra-high frequency bands and readers, which is applied in the direction of antennas, antenna supports/mounting devices, electrical components, etc., can solve problems such as narrow bandwidth, and achieve the effect of strong magnetic field, lower precision requirements, and frequency bandwidth

Inactive Publication Date: 2010-12-15
NORTHWESTERN POLYTECHNICAL UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Impinj company proposed a lot of antennas based on coupling loop; Siemens company proposed a folded loop antenna; Daniel M.Dobkin et al. proposed a loop antenna that compensates phase by lumped capacitor; the common feature of these antennas is to adopt a certain This method keeps the current on the ring in the same phase, so that the induced magnetic field is the strongest, but the above-mentioned antennas are resonant antennas, and the phase compensation amount is related to frequency, so the bandwidth is generally narrow

Method used

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  • Ultrahigh frequency band near field RFID reader-writer antenna
  • Ultrahigh frequency band near field RFID reader-writer antenna
  • Ultrahigh frequency band near field RFID reader-writer antenna

Examples

Experimental program
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Effect test

Embodiment 1

[0015] The length and width of the PCB substrate 5 and the metal floor 8 are 110mm and 50mm respectively; the PCB substrate 5 adopts FR4 dielectric board with a thickness of 1.5mm and a relative dielectric constant of 4.4; the thickness of the air layer 7 is 5mm.

[0016] Select the center conduction strip width and the slot width of the coplanar waveguide 2 so that its characteristic impedance is 50Ω, so as to match with the coaxial connector 1 . A balun with an impedance ratio of 1:4 is used. The port impedance of the balun 3 on the side of the coplanar waveguide 2 is 50Ω, and the port impedance on the side of the coplanar stripline 4 is 200Ω. The width of the conduction band of the coplanar stripline 4 is selected as 5mm and the distance between the conduction bands is 10mm, so that the characteristic impedance thereof is 200Ω. The impedance of the resistor 6 is 200Ω, which matches the characteristic impedance of the coplanar stripline 4 .

[0017] From the coaxial connec...

Embodiment 2

[0023] Both the reduction of the characteristic impedance of the coplanar strip line 4 and the increase of the thickness of the air layer 7 will increase the magnetic field strength and further extend the operating distance of the antenna.

[0024] The length and width of the PCB substrate 5 and the metal floor 8 are 110mm and 80mm respectively; the PCB substrate 5 is made of FR4 dielectric board with a thickness of 1.5mm and a relative dielectric constant of 4.4; the thickness of the air layer 7 is 10mm.

[0025] Select the center conduction strip width and the slot width of the coplanar waveguide 2 so that its characteristic impedance is 50Ω, so as to match with the coaxial connector 1 . A balun with a 1:2 impedance ratio is used. The port impedance of the balun 3 on the side of the coplanar waveguide 2 is 50Ω, and the port impedance on the side of the coplanar stripline 4 is 100Ω. The width of the conduction band of the coplanar stripline 4 is selected as 35mm and the dist...

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Abstract

The invention discloses an ultrahigh frequency band near field RFID reader-writer antenna. A coaxial connector is connected with one end of a coplanar waveguide on a PCB base plate; the other end of the coplanar waveguide is connected to one end of a coplanar strip line by a balun; the other end of the coplanar strip line is connected with a resistor; the PCB base plate and a metal floor are supported by nylon columns on four corners of the PCB base plate; an air layer is formed between the PCB base plate and the metal floor; and a conduction band width, a gap width between conduction bands, the dielectric constant of the PCB base plate, the thickness of the air layer, the impedance of the balun and the parameters of a resistance value are subject to properly matching the impedance among the coplanar waveguide, the balun, the coplanar strip line and the resistor. The invention has relatively wide frequency band and relatively strong magnetic field, and the antennas with different lengths can be conveniently designed according to the application requirements under different circumstances.

Description

technical field [0001] The invention belongs to the technical field of antenna structure design and relates to an RFID reader-writer antenna. Background technique [0002] RFID (Radio Frequency Identification, radio frequency identification) technology is a non-contact automatic identification technology. Reader antennas play a key role in RFID systems. The operating frequency of the reader antenna may be low frequency (below 135kHz), high frequency (13.56MHz), ultra-high frequency (860-960MHz) and microwave frequency band (above 2.4GHz). Reader antennas are divided according to the operating distance, which can be divided into near-field antennas and far-field antennas. Near-field reader antennas operating at UHF are ideal for working in tight spaces. Because the near-field antenna only has a strong electromagnetic field at a short distance, and the strength of the electromagnetic field weakens sharply at a slightly further distance, the far-field gain of this antenna is...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01Q1/14H01Q13/00H01Q13/08
Inventor 吴昌英任安康王婷郑奎松
Owner NORTHWESTERN POLYTECHNICAL UNIV
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