MEASUREMENT OF BACKSCATTERING FROM RFID TAGS

This paper presents a method for measuring signal backscattering from an RFID tag and calculating tag radar cross-section (RCS), which depends on the chip input impedance. We present a derivation of a theoretical formula for RFID tag radar cross-section and an experimental RCS measurement method using a network analyzer connected to an antenna in an anechoic chamber where the tag is also located. The return loss of the antenna measured with and without the tag present in the chamber allows one to calculate the power backscattered from the tag and find tag RCS. Measurements were performed in anechoic chamber using RFID tag operating in UHF band. Tag RCS was also calculated theoretically using tag impedance and gain obtained with electromagnetic simulation software. Theoretical results were found to be in good agreement with experimental measurements.

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