Phase modulation scheme for chipless RFID- and wireless sensor tags

Inspired by state of the art surface acoustic wave (SAW) technique an approach for the realization of chipless microwave RFID tags based on electrical circuits is proposed. For information coding of the retransmitted signal a passive QPSK coding scheme and for wireless monitoring of physical quantities an analog phase modulation scheme are investigated. Key elements for the realization of tags are lumped element delay lines. Therefore properties of left- and right-handed lines are discussed with the view on the special application. Finally, the proposed principles have been experimentally verified with a prototype.