Embedded Inductance Folded-Patch Antenna With Inclined Slots for On-Metal Tag Design

A novel radio frequency identification (RFID) folded-patch tag antenna that is designed using a double-layered configuration embedded with multiple inclined slots has been proposed for on-metal applications. The slots are functioning as a tuning mechanism for adjusting the operating frequency and antenna reactance. The operating frequency can be efficiently scaled down to the desired ultra-high frequency (UHF) band, while the reactance can be easily optimized to match with the chip reactance by adjusting the embedded inclined slots, without altering the antenna structure. The proposed tag antenna has a compact size of 32 mm
$\times $
40 mm
$\times 3$
.35 mm (
$0.097\lambda \times 0.122\lambda \times 0.010\lambda $
), and it can be fabricated on the single side of a thin polyimide substrate through chemical etching. The tag antenna has demonstrated a far-read distance of 16m when it is tested using an EIRP power of 4W. The stability of the tag operating frequency has been proven. It is unaffected by the size variation of the backing metal object.