Cost-effective electromagnetic characterization system for radiation pattern and sensitivity estimation of UHF RFID tags

The performance evaluation of radio-frequency identification (RFID) tags is an important task both for tag designers and final users. Approaches based on the use of Vector Network Analyzers rather than conventional RFID readers only provide partial characterizations. On the contrary, commercial solutions, although they are able to guarantee an accurate and complete performance evaluation, require significant investment. This work presents a cost-effective but accurate characterization system for the performance evaluation of UHF RFID tags. It is based on a programmable and GPIO-provided UHF RFID reader connected to a circularly polarized antenna and driving a stepper motor to modify the tag orientation. The system is able to determine the minimum power emitted by the interrogating reader capable to energize the tag under test, and to derive from it the most significant metrics characterizing the tags: maximum and angular tag sensitivity, maximum and angular working range, and tag antenna radiation pattern. The proposed UHF RFID tag characterization system is validated through comparison with a commercial solution in terms of tag sensitivity and radiation pattern which demonstrate the correctness of the proposed approach. © 2015 IEEE