Reconfigurable resonators for chipless RFID applications

Reconfigurable resonators for chipless RFID applications, comprising a resonator circuit having:

• a substrate;
• a plurality of microstrip resonators disposed on the substrate, each of the resonators including:
• a U-shaped spiral resonator frame having opposed parallel legs;
• and
• a plurality of parallel shorting elements extending between and spaced apart from the opposed parallel legs of the frame;
• and
• a transmission line extending parallel to one of the opposed parallel legs of the frame of each of the resonators, the transmission line being spaced from the frame leg a distance permitting coupling of microwave signals between the transmission line and each of the resonators, the transmission line having opposing ends, each of the ends being adapted for connection to a corresponding antenna for reception and transmission of an interrogation signal to and from an RFID reader in order to form a chipless passive RFID tag;
• wherein each of the resonators is configured to resonate in a separate and distinct frequency range from the other resonators forming a stopband filter having a resonant frequency within the separate and distinct frequency range;
• and
• wherein each of the resonators is adapted for reconfiguration of the stopband filter's resonant frequency by operation without a jumper or by installation of a conductive jumper between one of the shorting elements and the leg of the U-shaped resonator frame opposite the leg coupled to the transmission line.