Compact Printable Orientation Independent Chipless RFID Tag

A novel design concept of a compact printable orientation independent chipless RFID tag is presented. The tag consists of a circular patch loaded with multiple slot ring resonators. This symmetric frequency domain based tag has the advantage to be read from any orientation with the reader antennas. The tag can be read in close proximity by chipless RFID tag reader with waveguide(s) and also can be read in both near field and far-field of the RFID tag reader with antennas. This tag does not have a ground plane and has higher data density compared to the existing printable chipless tags. The usability of this single sided tag in close proximity is verified by waveguide measurements for both proximity applications such as on ID access cards, item level tagging etc. and slot reading application such as on banknotes, credit cards etc.