Label-type 3D RFID tag mountable on metallic and non-metallic objects

A study for reducing the sensitivity of label-type UHF RFID tags to background materials is done in this paper. It is found that the capacitance in parallel to the feeding point of the tag is the most sensitive element in the circuit. The capacitance of the antenna body is also found to be an important element. The bigger antenna capacitance leads to less sensitive tag designs. Based on these findings a low profile and low cost label-type tag design is proposed. The feeding point is protected by a bottom conducting layer in a 3D design and the dipole antenna is loaded with large capacitive patches at both tips. The tag not only shows acceptable reading range on various dielectric materials but also is capable of working on challenging materials like liquid bottles and metallic objects.