Compact battery-free UHF RFID tag for temperature measurement in poultry egg incubators

This paper presents the design of a battery-free chip-based UHF RFID sensor tag appropriate for temperature measurement inside a poultry egg incubator. The tag employs an EM4325 UHF RFID sensor chip that has a built-in temperature sensor. The antenna was connected to the chip via an internal impedance-matching circuitry and they were etched on an FR4 substrate. Tuning the antenna configuration to match the impedance of the chip and miniaturization of the tag size were performed using parametric optimization. Simulations were performed in ANSYS High-Frequency Structure Simulator (HFSS). The RFID tag, with a compact size of 75 × 20 × 1.6 mm
³
, performs well in terms of impedance matching, bandwidth, and radiation efficiency. Further, the proposed UHF RFID sensor tag demonstrates both far-field and near-field characteristics due to the antenna's dipole topology and loop structure respectively.