UHF RFID Tag Response Measurements Using a Do-It-Yourself Platform and Components Off-the-Shelf

In this article, we present cost-effective techniques to assess UHF RFID performance for real world applications. This includes a positioner, based on stepper motors and braided fishing lines, which can position a tag in 3-D space. In combination with inventory meta data like RSSI and phase, we previously showed its use for a variety of measurements, e.g., the influence of tag-distance to materials and other tags. In this work, we extend its range of applications by the investigation of polarization sensitive ground reflections and as reference for tag localization estimations. For the measurements themselves, we use a commercial off-the-shelf R420 Impinj reader, which we control via LLRP commands, implemented in Python. Using a low-cost RTL-SDR, we observed the communication between reader and tag and found out that the tag is responding for lower powers than the reader was able to detect it.