A Compact Dual-Band RFID Tag Antenna Mountable on Metallic Objects

A compact (50 × 50 × 4 mm3) dual-band radio frequency identification (RFID) tag antenna mountable on metallic objects is proposed for the ultra-high frequency (UHF) band (917∼923.5 MHz) and the microwave (MW) band (2.4∼2.45 GHz). With the proximity-coupled feed loop, the proposed antenna consists of two symmetric planar inverted-F antenna (PIFA) elements for the UHF band passive tag and a meander microstrip patch antenna for the MW band active tag. The performance of the proposed antenna is verified by mounting it on the different sizes of the metallic object. Furthermore, the passive tag antenna in the UHF band furthermore may be used for energy harvesting techniques to improve the lifetime of the active tag in the MW band. The measured maximum read range is 5.50 m in the UHF band and 14.15 m in the MW band when the proposed tag antenna is mounted on the metallic objects. The total efficiency for all operating frequency bands is higher than 50%. High isolation (>12 dB) between tag antennas in the UHF band and the MW band is achieved.