A Miniaturized Via-Patch Loaded Dual-Layer RFID Tag Antenna for Metallic Object Applications

In this letter, a dual-layer radio frequency identification (RFID) tag antenna is proposed. By embedding a slotted via-patch in the middle layer, the proposed antenna is miniaturized to a total volume of 28 × 14 × 3.2 mm³. At the same time, the loaded via-patch makes the antenna input impedance be flexibly tuned in a large scale. Moreover, an equivalent circuit model is given out to explicate how this via-patch functions. The measured read ranges with and without a metallic plate were 1.8 and 2 m, respectively, which implies the proposed antenna is a good candidate in metallic object applications, especially in size-constrained scenarios.