• chipless
• Costa
• mm-wave
• rfid
• Soldi
• tag
• Zhao

A new chipless RFID tag configuration operating in mm-wave frequency region (26 GHz – 40 GHz) has been designed, fabricated and tested. The tags consist of a shallow resonant cavity comprising a multi-resonant frequency selective surface printed on top of a thin grounded substrate. The presence of the ground plane plays an important role in converting polarization over multiple frequencies and guarantees the immunity to interference with other objects. The tags have been fabricated both on low-loss substrates with conventional photolithographic process and on paper by using a low-cost thermal printer. In the latter case the tag is thin, flexible and low-cost and therefore highly promising for practical applications like packaging. The proposed design approach allowed to achieve miniaturized and thinner tags with respect to those available in literature. Moreover, improved detectability compared to the state of the art has been proved by demonstrating a reading range larger than 1 m even without the use of signal processing. The tags are detectable without optical visibility or bent differently from optical technologies like barcodes.