Title: Characterisation of RF propagation in rectangular metal pipes for passive RFID systems

Authors: Darmindra D. Arumugam, Daniel W. Engels

Addresses: Department of Electrical Engineering, University of Texas, Arlington, TX 76019-0016, USA. ' Department of Electrical Engineering, University of Texas, Arlington, TX 76019-0016, USA

Abstract: In this paper, we collect and extend the theory of Radio Frequency (RF) propagation within rectangular metal pipes. This work is motivated by the need to understand the operation of UHF Radio Frequency Identification (RFID) systems when the tags are placed within rectangular metal pipes. The field components inside a rectangular metal pipe are derived to obtain the propagation and attenuation constants, modal cutoff frequency relationships, the different Transverse Electric (TE) and Transverse Magnetic (TM) modes. The cutoff frequencies, attenuation and angle of incidence are used within the theory to identify operating limitations of passive RFID systems in hollow rectangular metal pipes. This theory is combined with existing theories of propagation within cylindrical metal pipes to present a comprehensive general theory. Analytical evaluations are used to visualise the tags within the metal pipes and to validate the theory presented in this paper. It is shown that passive UHF RFID tags can be read even below the cutoff frequencies of these rectangular metal pipes when used under the guidance of the general theory.

Keywords: radio frequency identification; UHF RFID; passive RFID; electromagnetic propagation; EM; waveguide theory; rectangular metal pipes; radio frequency propagation; hollow metal pipes; cylindrical metal pipes.

DOI: 10.1504/IJRFITA.2007.017746

International Journal of Radio Frequency Identification Technology and Applications, 2007 Vol.1 No.4, pp.345 - 362

Published online: 29 Mar 2008 *

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