Desptie its popularity, radio-frequency identification's (RFID's) progress could be hampered by cost, reliability, the need for environmentally friendly materials, and the requirements put on tags by worldwide regulatory efforts. Such challenges could be easily conquered by the inkjet printing of antennas and matching networks on low-cost, paper-based materials. At the Georgia Institute of Technology, Amin Rida, Li Yang, Rushi Vyas, and Manos M. Tentzeris have presented a compact, inkjet-printed, ultra-high-frequency (UHF) passive- RFID antenna as a demonstration prototype.
In using paper as a substrate for high-frequency applications, the researchers found that it had good electrical/dielectric performance to at least 1 GHz. Because of the wide variety of types of paper, it is essential to perform dielectric RF characterization of paper substrates before the RF on-paper designs. To measure the dielectric constant and loss tangent of paper to 2 GHz, a microstrip-ring resonator was designed. Typical SMA coaxial connectors were used to feed the ring-resonator structure. The through-reflect-lines (TRL) calibration method was employed to de-embed the effect of the feeding lines. Insertion-loss measurements were performed from 0.4 to 1.9 GHz using an 8530A vector network analyzer (VNA) from Agilent Technologies.
The researchers designed and fabricated a T-match folded-bowtie, half-wavelength dipole antenna on commercial photo paper using an inkjet printer. The antenna was designed using Ansoft's HFSS 3D electromagnetic (EM) solver. They also demonstrated the capabilities of inkjet printing technology in integrating wireless sensors on paper, thereby bridging RFID and sensing technology. See "Conductive Inkjet-Printed Antennas on Flexible Low-Cost Paper-Based Substrates for RFID and WSN Applications," IEEE Antennas And Propagation Magazine, June 2009, p. 13.
