Effects of a Metal Plane on a Meandered Slot Antenna for UHF RFID Applications

Kim, Ji-Kwon; Oh, Il-Young; Koo, Tae-Wan; Kim, Jun-Chul; Kim, Dong-Su; Yook, Jong-Gwan

doi:2012.12.2.176

J. Electromagn. Eng. Sci > Volume 12(2); 2012 > Article

Journal of Electromagnetic Engineering and Science 2012;12(2):176-184.
DOI: https://doi.org/10.5515/JKIEES.2012.12.2.176

Effects of a Metal Plane on a Meandered Slot Antenna for UHF RFID Applications

Ji-Kwon Kim¹, Il-Young Oh¹, Tae-Wan Koo¹, Jun-Chul Kim², Dong-Su Kim², Jong-Gwan Yook¹

¹Dept. of Electrical and Electronics Engineering, Yonsei University
²System Packaging Center of Korea Electronics Technology Institute

Abstract

In this paper, the effects of a metal plane on the performance of a meandered slot RFID antenna are evaluated in a real environment, and 3 metal plane cases are considered (the most likely scenarios in which metal conductive materials are placed near the tag antenna). The metal plane effects can be categorized as matching degradation and antenna gain variation. First, matching degradation due to the antenna's induced mutual impedance is experimentally investigated. In addition, the gain variation is investigated to figure out the change in the radiation characteristics. With the derived antenna parameters, the read range is calculated with the Friis transmission equation and measured to analyze the effects of a metal plane on RFID system performance. The calculated and measured read range varies from 9.3 m to 19.1 m as the distance between the RFID antenna and the metal plane changes.

Key words: RFID, Mutual Impedance, Metal Effects, Friis Transmission Equation, Slot Antenna