Effects of printed circuit board on the performance of tag antennas for passive RFID

This article presents a study of the effects that an UHF (Ultra High Frequency) Passive RFID (Radio Frequency Identification) tag suffers when inserted on a PCB (Printed Circuit Board). The normal tags when are glued to electronic boards, they suffer from degradation in performance due to the presence of the metals plans and the respective traces and vias present in the electronics projects. The objective of this study is to identify the main features that should be considered in RFID UHF tags projects designs on printed circuit boards and develop a method to insert UHF RFID tags on PCBs. It was used here a folded dipole. First of all, it is shown the designs performance out of the PCB, without metals planes, traces and vias interference. After the design modeling, it was carried out simulations on CST to optimize the projects for one and two layers PCBs, working with the thickness of the cooper and the PCBs dielectric, the tag position on the PCB and the antennas parameters to attain impedance matching with IC (Integrated Circuit). Finally, it was manufactured one and two layers PCBs with the RFID tags to test in anechoic RF chamber. The results show that if the antenna design was developed with the methods described on this study, the strong influence of the PCB metals parts on tags performance will be reduced significantly and the manufacture of RFID tags on electronics boards become possible.