NIST logo

Publication Citation: Reference Modulation for Calibrated Measurements of Tag Backscatter

NIST Authors in Bold

Author(s): Daniel G. Kuester; David R. Novotny; Jeffrey R. Guerrieri; Randy Direen; Zoya Popovic;
Title: Reference Modulation for Calibrated Measurements of Tag Backscatter
Published: April 14, 2011
Abstract: We present a model and reference backscatter device for calibrating measurements of 860-960 MHz Ultra-High Fre- quency (UHF) tag backscattering. The model relates transmission to and backscattering from the device with a modulation depth calculable from circuit parameters. Unlike the free-space far field approximations, the model is valid in arbitrary stationary linear environments, including the near field of a transmit or measurement antenna, via S-parameters. We use the model to demonstrate an inexpensive reference backscatter device with a common lab switch and loads. Validation measurements on a network analyzer with two expressions for modulation depth agree to within 0.1 dB at 915 MHz. Finally, we present some initial calibrated measurements of backscattered power from a tag at 915 MHz, with estimated uncertainty -0.7 dB to +0.6 dB.
Proceedings: 2011 IEEE International Conference on RFID
Pages: 8 pp.
Location: Orlando, FL
Dates: April 12-14, 2011
Keywords: RFID, UHF, backscatter, modulation
Research Areas: Wireless