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Design of Tag Antenna without Shadow Zone in Readable Pattern  

Cho, Chi-Hyun (School of Electronic and Electrical Engineering, Hongik University)
Choo, Ho-Sung (School of Electronic and Electrical Engineering, Hongik University)
Park, Ik-Mo (Department of Electrical and Computer Engineering, Ajou University)
Publication Information
The Journal of Korean Institute of Electromagnetic Engineering and Science / v.16, no.12, 2005 , pp. 1206-1212 More about this Journal
Abstract
In this paper, we propose a novel antenna structure which uses the electric and magnetic currents so as to eliminate nulls on their radiation pattern. The tag antenna was matched to the conjugate impedance of the commercial tag chip using the modified double T matching network. The radiation efficiency is about $90\%$, and the bandwidth($S_{11}< -10 dB$) is 848${\~}$926 MHz. Also it shows the gain deviation between the maximum and minimum gains about 4 dB at any direction of the tag antenna at the operating frequency. The readable range of the tag is 1.7${\~}$2.4 m for an arbitrary rotation angle of the tag with a commercial tag chip.
Keywords
RFID; Antenna; Tag; Isotropic Radiation Pattern; Genetic Algorithm;
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