Towards Array and Curve Analysis: Flexible Passive Chipless RFID Tags

This research is intended to characterize the performance of chipless RFID tags for curved surface utilizing array-based structures. Here in, paper covers design of tag, simulation results of proposed array tag, fabrication, and experimental results of bent/curved chipless RFID tags. Semi octagonal shape passive chipless RFID tags have been fabricated using polyethylene terephthalate (PET) substrate with silver nano particle-based ink as top layer both as single unit tag having 10-bit data and 5 x 5 array-based structures. Extensive simulation and experimental results detail out the response of array based chipless RFID tag along with bending effects. Complete analysis and study of folding effects provides an alteration in radar cross section (RCS) of chip-free tag along with variation in bending radius of the tag. A bend radius of (100mm to 3mm) for material under test (MUT) is analyzed. The original single unit tag has dimensions of 13mm x 7mm, whereas 5 x 5 array structure comes up to 75mm x 43.5mm size of tag. It has been analyzed that with increment of every unit in single unit tag, the RCS magnitude response increases but, RCS reaching greater than -10 dBsm, is not in detectable range, so that is cut-off limit for 5 x 5 array for proposed tag. Also, with decreasing bend radius, the RCS response of chipless RFID tag decreases from -43 dBsm to -65 dBsm, but after certain limit below 15mm, attenuation in response is not recoverable. The proposed research is intended to provide cost-effective solution towards flexible/bendable applications.