Microwave performance of flexo-printed chipless RFID tags

The chipless RFID tag is considered as a potential candidate to replace the expensive chip-based tags due to the possibility of high volume tag production by low-cost printing processes. In this paper, we report on the microwave performance of chipless tags printed by a benchtop flexographic printer using low-cost water-based silver ink obtained from NovaCentrix. The designed chipless RFID tags were based on the frequency-domain ‘Data Encoding’ due to its merit to encode a higher number of data bits compared to other domains of data encoding. The printed silver ink tracks were optimized for best printer settings in terms of the adjustments of the gap between the rollers, print speed and ink volume. The dependence of the RCS response on the actual tag area to be covered in metal ink, relative to the designed tag area, was investigated and a way to obtain an increased RCS response was studied. It was found that printing at least two copies of resonators can enhance the detected RCS response for any specific tag configuration. Tags printed on Mylar PET film gave the best RCS performance compared to tags printed on thermal paper and PVC film.