A Hybrid UHF RFID Tag Robust to Host Material

A novel hybrid ultra-high frequency radio frequency identification tag is proposed in this paper. The tag offers the advantage of both dipole type and patch antenna depending on the object it is placed on. The label-type dipoles are not functional on metallic objects and patch antennas are not efficient on non-metallic objects, whereas the proposed tag is a dual port design thus it is capable of working in two different modes in off-metal and on-metal scenarios. In off-metal mode, the tag works as a dipole antenna designed on an FR-4 substrate with 3.2 mm thickness. The wide capacitive loaded dipole arms and optimum tuned impedance matching between the chip and the antenna increase the robustness and limit the detuning effect in off-metal mode. The metallic surface of the host material acts as the ground plane in on-metal mode and the tag transforms into a short-ended quarter wavelength patch antenna. The measurement result confirms a long read range between 8 and 12 m in off-metal mode depending on the host material and 5.6 m in on-metal mode.