Variation of signal strength and electromagnetic field pattern in conveyor-based radio frequency identification systems
Source: International Journal of Radio Frequency Identification Technology and Applicat, Volume 3, Number 3, June 2011 , pp. 181-194(14)
Publisher: Inderscience Publishers
Abstract:In this paper, we study the characteristics and variation of RF signal strength and electromagnetic (EM) field pattern in a conveyor-based RFID application, and their impact on readability of passive UHF RFID tags. Read-rate (number of reads per second) and received signal strength indicator (RSSI) are employed as a measure of the signal strength within the EM field. It is shown that EM field patterns significantly change depending on the position of tagged case(s) containing metal products, and the number of cases within the read zone. The presence of metal can create read null points in proximity distance to the reader resulting from multipath reflections from objects in the conveyor system environment. Understanding how such significant factors affect the signal strength and EM field pattern is essential for designing an optimised RFID system to achieve a desired level of performance.
Document Type: Research article
Affiliations: 1: UW RFID Lab, Department of Industrial and Systems Engineering, University of Wisconsin-Madison, 4158 Mechanical Engineering Building, 1513 University Avenue, Madison, WI 53706-1572, USA. 2: Department of Industrial and Systems Engineering, University of Wisconsin-Madison, 4101 Mechanical Engineering Building, 1513 University Avenue, Madison, WI 53706-1572, USA
Publication date: 2011-06-01