Development of Optically Transparent Ultrathin Microwave Absorber for Suppression of Misidentification Possibility of UHF-RFID System

Recently, wireless telecommunication devices have been used with the worldwide spread of the mobile phone, wireless local area networks WLAN, and UHF-radio frequency identification UHF-RFID. Therefore, EMI problems have also been serious. In the case of indoor use, the wireless telecommunication environment is degraded by multiple reflection interference. That interference must be controlled in order to improve wireless communication conditions. In particular, improvement of the multipath environment is regarded as indispensable for assuring reliability UHF-RFID systems. In this paper, an ultrathin microwave absorber is described as a technology for improving the multipath environment for UHF-RFID system. Additionally, provision is made for transparency of this absorber, because microwave absorbers should not increase the blind area of the observation camera in the region in which the UHF-RFID system is used around the entrance gate of offices or warehouses. Verification of tag identification probability improvement with this absorber in an actual warehouse is also presented.

[1]  A. Taflove,et al.  Numerical Solution of Steady-State Electromagnetic Scattering Problems Using the Time-Dependent Maxwell's Equations , 1975 .

[2]  R. Fante,et al.  Reflection properties of the Salisbury screen , 1988 .

[3]  Anders Karlsson,et al.  On the Absorption Mechanism of Ultra Thin Absorbers , 2010, IEEE Transactions on Antennas and Propagation.

[4]  G. Iannaccone,et al.  Design criteria for the RF section of UHF and microwave passive RFID transponders , 2005, IEEE Transactions on Microwave Theory and Techniques.

[5]  Yoshinobu Okano.  Development of Thin Electromagnetic Wave Absorption Wall using Patch Elements , 2009, 2009 20th International Zurich Symposium on Electromagnetic Compatibility.

[6]  A.A.M. Saleh,et al.  A Statistical Model for Indoor Multipath Propagation , 1987, IEEE J. Sel. Areas Commun..

[7]  K. Sarabandi,et al.  A one-layer ultra-thin meta-surface absorber , 2005, 2005 IEEE Antennas and Propagation Society International Symposium.

[8]  Henry L. Bertoni,et al.  UHF propagation prediction for wireless personal communications , 1994, Proc. IEEE.

[9]  S. Tretyakov,et al.  Simple and Accurate Analytical Model of Planar Grids and High-Impedance Surfaces Comprising Metal Strips or Patches , 2007, IEEE Transactions on Antennas and Propagation.

[10]  A. Lázaro,et al.  Radio Link Budgets for UHF RFID on Multipath Environments , 2009, IEEE Transactions on Antennas and Propagation.

[11]  W. C. Jakes,et al.  Microwave Mobile Communications , 1974 .

[12]  William C. Y. Lee,et al.  Mobile Communications Engineering , 1982 .

[13]  R. Luebbers,et al.  The Finite Difference Time Domain Method for Electromagnetics , 1993 .