Miniature Folded Dipolar Patch With Embedded AMC for Metal Mountable Tag Design

A miniature folded radio frequency identification (RFID) tag antenna which has an embedded artificial magnetic conductor (AMC) structure is proposed for the first time. The AMC occupies no footprint virtually as it is embedded inside the antenna itself. By incorporating an interlayer AMC in between a dipolar patch and its ground plane, the tag resonant frequency can be easily scaled down to the useful ultrahigh frequency (UHF) band with good realized gain and far read distance. The proposed tag antenna can be easily fabricated on a single piece of a thin flexible polyethylene terephthalate (PET) substrate by using the standard printed-circuit-board (PCB) processes. With a compact size of only 30 mm $\times50$ mm $\times3.35$ mm $(0.092 \lambda \times 0.153 \lambda \times 0.010\lambda)$ , the proposed tag is able to achieve a far read distance of 9.8 m when it is measured using an effective isotropic radiated power (EIRP) power of 4 W. The tag resonant frequency is proven to be very stable and insensitive to the variations of the backing metal.