Small 3D-Dipole Antenna for RFID Tag Mounted on a Full Container of Water

This study developed a novel 3D-dipole antenna for radio frequency identification (RFID) that mounted on a container of water. Conjugate matching of the resistance and inductive reactance of the antenna to the desired impedance of Alien Higgs-4 chip ($8.2-j148.5\Omega$ at 925 MHz) can be performed by simply tuning the C-arm length of the 3D-dipole. After analysis and optimization of the tag antenna has an overall size of $32\times 25\times 3.2\ \text{mm}^{3} (0.10\ \lambda_{0}\times 0.08\ \lambda_{0}\times 0.01\ \lambda_{0})$, the fabricated tag mounted on a container of water testing of an RFID reader with an effective isotropic radiated power (EIRP) of 4.0 W yield the maximum read ranges in an outdoor environment of 5.3 and 3.9 m, respectively. Measurement data agreed with simulation results.