A Compact Broadband Circularly Polarized Antenna with a Backed Cavity for UHF RFID Applications

Junlong Li, Hui Liu, Shuai Zhang, Yuan Zhang, Sailing He

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

A compact broadband circularly polarized antenna is designed with a novel method for universal ultra high frequency (UHF) radio frequency identification (RFID) readers. It is composed of a compact ring-shaped patch which aims to decrease the size of the antenna. A quadrature 3 dB coupler placed below the ground plane creates 90° phase differences to generate the circularly polarized radiation of the antenna. To improve the performance of the proposed antenna and minimize its size, we use a coupling feeding method, an FR4 dielectric slab, and a metal cavity. The coupled feeding is implemented to eliminate the mismatching between the long probe and ring-shaped patch, and to improve
the gain over the operating band. The introduction of an FR4 dielectric slab and a cavity can reduce the antenna size and improve the impedance matching and axial ratio (AR) bandwidth. The antenna with a backed cavity can increase the front to back ratio remarkably and improve CP performance further. The measured results show that the antenna with a low profile (0.45λ×0.45λ×0.06λ at 915 MHz) has the impedance bandwidth of 30.2 % (730-990MHz) and 3-dB AR bandwidth of 24.2% (760-970MHz). Both the impedance and the AR bandwidth cover the worldwide UHF RFID band.
Original languageEnglish
JournalIET Microwaves, Antennas & Propagation
Number of pages9
ISSN1751-8725
DOIs
Publication statusPublished - 2019

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Radio frequency identification (RFID)
Antennas
Bandwidth
Radiation
Metals

Cite this

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title = "A Compact Broadband Circularly Polarized Antenna with a Backed Cavity for UHF RFID Applications",
abstract = "A compact broadband circularly polarized antenna is designed with a novel method for universal ultra high frequency (UHF) radio frequency identification (RFID) readers. It is composed of a compact ring-shaped patch which aims to decrease the size of the antenna. A quadrature 3 dB coupler placed below the ground plane creates 90° phase differences to generate the circularly polarized radiation of the antenna. To improve the performance of the proposed antenna and minimize its size, we use a coupling feeding method, an FR4 dielectric slab, and a metal cavity. The coupled feeding is implemented to eliminate the mismatching between the long probe and ring-shaped patch, and to improvethe gain over the operating band. The introduction of an FR4 dielectric slab and a cavity can reduce the antenna size and improve the impedance matching and axial ratio (AR) bandwidth. The antenna with a backed cavity can increase the front to back ratio remarkably and improve CP performance further. The measured results show that the antenna with a low profile (0.45λ×0.45λ×0.06λ at 915 MHz) has the impedance bandwidth of 30.2 {\%} (730-990MHz) and 3-dB AR bandwidth of 24.2{\%} (760-970MHz). Both the impedance and the AR bandwidth cover the worldwide UHF RFID band.",
author = "Junlong Li and Hui Liu and Shuai Zhang and Yuan Zhang and Sailing He",
year = "2019",
doi = "10.1049/iet-map.2018.5321",
language = "English",
journal = "IET Microwaves, Antennas & Propagation",
issn = "1751-8725",
publisher = "Institution of Engineering and Technology",

}

A Compact Broadband Circularly Polarized Antenna with a Backed Cavity for UHF RFID Applications. / Li, Junlong; Liu, Hui; Zhang, Shuai; Zhang, Yuan; He, Sailing.

In: IET Microwaves, Antennas & Propagation, 2019.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - A Compact Broadband Circularly Polarized Antenna with a Backed Cavity for UHF RFID Applications

AU - Li, Junlong

AU - Liu, Hui

AU - Zhang, Shuai

AU - Zhang, Yuan

AU - He, Sailing

PY - 2019

Y1 - 2019

N2 - A compact broadband circularly polarized antenna is designed with a novel method for universal ultra high frequency (UHF) radio frequency identification (RFID) readers. It is composed of a compact ring-shaped patch which aims to decrease the size of the antenna. A quadrature 3 dB coupler placed below the ground plane creates 90° phase differences to generate the circularly polarized radiation of the antenna. To improve the performance of the proposed antenna and minimize its size, we use a coupling feeding method, an FR4 dielectric slab, and a metal cavity. The coupled feeding is implemented to eliminate the mismatching between the long probe and ring-shaped patch, and to improvethe gain over the operating band. The introduction of an FR4 dielectric slab and a cavity can reduce the antenna size and improve the impedance matching and axial ratio (AR) bandwidth. The antenna with a backed cavity can increase the front to back ratio remarkably and improve CP performance further. The measured results show that the antenna with a low profile (0.45λ×0.45λ×0.06λ at 915 MHz) has the impedance bandwidth of 30.2 % (730-990MHz) and 3-dB AR bandwidth of 24.2% (760-970MHz). Both the impedance and the AR bandwidth cover the worldwide UHF RFID band.

AB - A compact broadband circularly polarized antenna is designed with a novel method for universal ultra high frequency (UHF) radio frequency identification (RFID) readers. It is composed of a compact ring-shaped patch which aims to decrease the size of the antenna. A quadrature 3 dB coupler placed below the ground plane creates 90° phase differences to generate the circularly polarized radiation of the antenna. To improve the performance of the proposed antenna and minimize its size, we use a coupling feeding method, an FR4 dielectric slab, and a metal cavity. The coupled feeding is implemented to eliminate the mismatching between the long probe and ring-shaped patch, and to improvethe gain over the operating band. The introduction of an FR4 dielectric slab and a cavity can reduce the antenna size and improve the impedance matching and axial ratio (AR) bandwidth. The antenna with a backed cavity can increase the front to back ratio remarkably and improve CP performance further. The measured results show that the antenna with a low profile (0.45λ×0.45λ×0.06λ at 915 MHz) has the impedance bandwidth of 30.2 % (730-990MHz) and 3-dB AR bandwidth of 24.2% (760-970MHz). Both the impedance and the AR bandwidth cover the worldwide UHF RFID band.

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SN - 1751-8725

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