Influence of the Non-Linear UHF-RFID IC Impedance on the Backscatter Abilities of a T-Match Tag Antenna Design

• Published in: IEEE transactions on magnetics Vol. 48; no. 2; pp. 755 - 758
• Main Authors: Bauernfeind, Thomas, Preis, Kurt, Koczka, Gergely, Maier, Stefan, Biro, Oszkar
• Format: Journal Article Conference Proceeding
• Language: English
• Published: New York, NY IEEE 01-02-2012; Institute of Electrical and Electronics Engineers
• Subjects: Antenna measurements; Cross-disciplinary physics: materials science; rheology; Dipole antennas; Exact sciences and technology; Impedance; Integrated circuits; Materials science; Other topics in materials science; Physics; Radar cross section; radio-frequency-identification (RFID) tag; Transponders; UHF antennas; ultra-high-frequency (UHF) antennas; Design; ultra-high-frequency (UHF) antennas; Radar cross section; Impedance; radio-frequency-identification (RFID) tag; Magnetic properties
• ISSN: 0018-9464; 1941-0069
• DOI: 10.1109/TMAG.2011.2174971

In ultra-high-frequency radio-frequency-identification (UHF-RFID) the conjugate complex matching of the packaged UHF-RFID transponder IC and the tag antenna structure is important to increase the reading range of the transponder tag. Quite often half-wavelength dipole-like antenna structures are used. Due to the fact that the impedances of the packaged IC and the dipole antenna structure are in different domains, a matching structure is needed to accomplish the conjugate complex matching. A common technique to carry out the matching is the so called T-match. Since the nominal input impedance of the IC depends on the applied antenna voltage (and in a strongly non-linear way), the backscatter abilities of the tag are also functions of the applied voltage. In the present work those dependencies are investigated in terms of full-wave finite element simulations and measurements.