Passive UHF-RFID tags for Blu-ray discs

Summary form only given. RFID technology allows identification of objects, animals and persons by using electromagnetic waves. In the last years, the use of such technology has experienced a rapid increase, whereas the cost of the tags has dropped down. Nevertheless, a major challenge is tagging metallic objects, since conventional UHF-RFID tags do not work properly over this kind of surface material. Optical discs, which are commonly used nowadays, are among these items due to the presence of a metal film under the disc surface. For this reason, optical discs cannot be tagged efficiently by using conventional UHF-RFID tags, and special solutions need to be developed. a UHF-RFID passive tag for Blu-ray discs (BDs) will be presented in this work.The tag design is based on the approach (proposed by Zuffanelli et al., IEEE Transactions on Antennas and Propagation, 61, 5860, 2013) where the sputtered metallic layer of the optical disc behaves as the main radiator. This strategy allows obtaining read ranges in the order of several meters, while providing worldwide operation. In the abovementioned work, a UHF-RFID tag for DVD discs was proposed as a proof of concept. Based on the NXP UCODE G2XM integrated circuit, a prototype was simulated and fabricated, and a peak read range of 5 m was measured, in very good agreement with simulations. The method can in principle be applied to all kind of optical discs, though some structural differences (e.g. thickness and composition of the metal layer, geometric arrangement of the disc layers) between the disc types could lead to changes in the radiation efficiency of the tag, which is related to its final read range. Moreover, the same differences could cause a variation of the antenna impedance, as seen from the ASIC, thus requiring the study of an impedance matching strategy. In this work, the authors explore the possibility of applying the abovementioned method to the design of UHF-RFID tags for Blu-ray discs. Firstly, in order - o study the performance of the tag in terms of read range, the antenna gain of the disc was evaluated by means of EM simulation. Then, following the design process established in the previous work, the tag geometry was adjusted. At this stage, in order to obtain good impedance matching between the antenna and the Alien Higgs3 ASIC, an additional matching element was introduced in this work. To validate the simulated results, a prototype of the tag was fabricated, and the read range was measured.