Design and fabrication of ultra-low cost radio frequency identification antennas and tags exploiting paper substrates and inkjet printing technology

This work deals with the design and fabrication of antennas for radio frequency identification (RFID) tag devices operating in the low microwave frequency range. Paper substrate material and inkjet printing process have been used to guarantee mechanical flexibility and ultra-low production costs of the antenna. A new antenna design methodology has been developed with the purpose to minimise the amount of both substrate material and conductive ink. The first goal is achieved by reducing, for a given frequency, the antenna size. The second goal, instead, is pursued by studying the surface current density distribution along the antenna and removing the metal material where such a current density is negligible. The above methodology has been applied to several antennas designs ranging from a windshield sticker tag to an RFID-SAW antenna. Moreover a 3.5 GHz crossed-dipole tag, based on the frequency-doubling mechanism, is reported along with a possible modification to enable wireless sensing. The experimental characterisation of these prototypes validates the proposed design methodology opening, in the mean time, the possibility for ultra-low cost mass production of RFID tag devices based on paper materials.