A Directional, Closely Spaced Zero-Phase-Shift-Line Loop Array for UHF Near-Field RFID Reader Antennas

Yunjia Zeng, Zhi Ning Chen, Xianming Qing, Jian Ming Jin

Research output: Contribution to journalArticle

Abstract

A zero-phase-shift-line (ZPSL) loop array with two closely spaced elements is proposed to achieve a directional distribution for ultrahigh frequency (UHF) near-field radio frequency identification (RFID) applications. The proposed array consists of two coaxially positioned ZPSL loop antenna elements of the same size, with an aperiodic ZPSL loop acting as a driven element and a periodic ZPSL loop functioning as a parasitic element. A directional magnetic field distribution can be achieved when an out-of-phase current along the parasitic loop is induced. A ZPSL loop array prototype with an interelement spacing of 15 mm, or 0.046 of the operating wavelength at 915 MHz, achieves a desired directional magnetic field distribution over a circular interrogation zone with a diameter of 160 mm. As a UHF near-field RFID reader antenna, the proposed array is able to achieve a 100% detection rate of SAG tags up to 120 mm by using an Impinj Speedway reader with an output power of 30 dBm.

Original languageEnglish (US)
Article number8421640
Pages (from-to)5639-5642
Number of pages4
JournalIEEE Transactions on Antennas and Propagation
Volume66
Issue number10
DOIs
StatePublished - Oct 2018

Keywords

  • Antenna array
  • directional antenna
  • parasitic array
  • radio frequency identification (RFID)
  • zero-phase-shift-line (ZPSL) loop antenna

ASJC Scopus subject areas

  • Electrical and Electronic Engineering

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