A Two-Element Circularly-Polarized Antenna Array for UHF-Band RFID Reader Applications

Park, Joung-Min; Kim, Yun-Mi; Ahn, Bierng-Chearl; Park, Chan-Sik; Cha, Eun-Jong

Journal of the Korean Institute of Electromagnetic and Science 2006;6(1):36-46.

Joung-Min Park¹, Yun-Mi Kim¹, Bierng-Chearl Ahn¹, Chan-Sik Park¹, Eun-Jong Cha²

¹School of Electrical and Computer Engineering, Chungbuk University
²School of Medicine, Chungbuk University

Abstract

In this paper, we present a two-element circularly-polarized antenna array for UHF-band RFID reader applications. The antenna element in the array is a comer-truncated rectangular patch placed on a thick plastic-foam dielectric. The patch is fed on one of its edges by a microstrip line printed on a separate thin substrate. The array antenna is fed by a microstrip power divider. Parametric studies on the patch are carried out, from which an optimum design of a single antenna element is derived. The element spacing and the feed network of the array are investigated. A commercial electromagnetic software is employed in the analysis and design of the antenna. The designed array is fabricated and tested. Measurements show good performance characteristics of the fabricated antenna: a 11.2-dBi gain, a reflection coefficient of - 14 dB, an axial ratio less than 3 dB over 3-dB beamwidths of 40 and 60 degrees on two principal planes.

Key words: RFID Reader Antenna, Circularly-Polarized Antenna, Patch Array Antenna