Miniature PIFA-like Patch Antenna for UHF RFID Tag Design

A miniature metal-mountable UHF tag antenna with a geometrical dimension of 32 mm $\times$ 35 mm $\times$ 1.6 mm (0.097$\lambda$ $\times$0.106$\lambda$$\times$0.0049$\lambda$) is proposed. It is made of two planar inverted-F antennas (PIFAs) placing side-by-side. Two pairs of notches are created on the top surface of the patches for tuning the tag's resonant frequency. The antenna impedance can be easily matched with the chip impedance at different tag's resonances. It is found that the realized gain of the tag antenna can be improved by broadening the vertical arm width. With the use of 4W EIRP, the tag antenna is found to be able to achieve a measured read range of 8.7 m on metals, with little fluctuation in the tag's resonance for all cases.