Detection of Massive Numbers of Dvds by a Uhf Rfid System

This paper aims to provide an effective solution to the problem of detecting a large number of densely stacked DVDs. The number is in the range of 2000. In order to achieve that goal, firstly the structure and the properties of materials comprising a DVD disc and a DVD case are investigated. The effect of the metal layer in the disc on the interrogating wave is evaluated via theoretical analysis and simulation. Based on that analysis and simulation, and on numerous experiments on either a single labeled DVD in free space or multiple labeled DVD in a DVD stack, two solutions are proposed whereby over 95% DVDs in a great portion of a 2000 DVD stack could be detected. Eliminating the tags which have weak performance, the percentage can be 100%. This paper not only expands the range of categories detectable by UHF RFID systems but also provides a process and method for item-level tagging in which the number of the items is in the range of thousands.