A Low-Profile Broadband Circularly Polarized Slot Antenna Loaded With Metasurface for UHF-RFID Readers

A low-profile broadband antenna with high-gain circularly polarized (CP) radiation is proposed for ultra-high frequency (UHF) radio frequency identification (RFID) readers. The design is a sequentially rotated <inline-formula> <tex-math notation="LaTeX">$2\times 2$ </tex-mat...

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Bibliographic Details
Main Authors: Thi Ngoc Hien Doan, Hai Dang Le, van Son Hoang, Khac Kiem Nguyen, Son Xuat Ta
Format: Article
Language:English
Published: IEEE 2025-01-01
Series:IEEE Access
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Online Access:https://ieeexplore.ieee.org/document/11015972/
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Summary:A low-profile broadband antenna with high-gain circularly polarized (CP) radiation is proposed for ultra-high frequency (UHF) radio frequency identification (RFID) readers. The design is a sequentially rotated <inline-formula> <tex-math notation="LaTeX">$2\times 2$ </tex-math></inline-formula> CP slot array. Each slot element utilizes two 45&#x00B0;-rotated stubs to introduce proper structural asymmetry, and consequently, achieve CP radiation. The array is fed by a sequential-phase feeding network for improving CP radiation in terms of gain and 3-dB axial ratio (AR) bandwidth. For a broadside radiation, the slot array is backed by a ground plane (GND). A metasurface, which is composed of <inline-formula> <tex-math notation="LaTeX">$6\times 6$ </tex-math></inline-formula> periodic metallic plates, is inserted between the array and GND to allow a low profile with high efficiency. The final design with overall size of <inline-formula> <tex-math notation="LaTeX">$210\times 210\times 32.4$ </tex-math></inline-formula> mm3 (<inline-formula> <tex-math notation="LaTeX">$0.6\lambda \times 0.6\lambda \times 0.09\lambda $ </tex-math></inline-formula> at 0.86 GHz) has been fabricated and measured. The measurements result in a 10-dB return-loss bandwidth of <inline-formula> <tex-math notation="LaTeX">$0.81-0.96$ </tex-math></inline-formula> GHz, a 3-dB AR bandwidth of <inline-formula> <tex-math notation="LaTeX">$0.86-0.93$ </tex-math></inline-formula> GHz, and broadside right-hand CP radiation with the peak gain of 8.7 dBic.
ISSN:2169-3536