RFID antenna humidity sensor co-design for USN applications

Abstract

We demonstrate for the first time an RFID tag antenna which itself is humidity sensor and also provides calibration functionality. The antenna is comprised of T-matching network and horizontally meandered lines for impedance matching and reliable near-field communication. The novel contour design provides humidity sensing, and calibration functions whilst concurrently acts as a radiating element along with quadrangular capacitive tip-loading with covered middle portion for far-field communication. The inkjet printed prototypes of the antenna provide effective ambient humidity sensing while demonstrating stable RFID communication. The antenna has a compact size of 1.1 × 10.2 cm for 902-928MHz band. © IEICE 2013.