Shorted Patch Antenna with Tuning Slit for RFID Tag Mounted on Metallic Plane

Shorted Patch Antenna With Multi Slots for a UHF RFID Tag Attached to a Metallic Object

“…Further, these antennas have a three-layer design with radiating aluminum plates, making it more difficult to achieve impedance matching with the microchip. The tag antenna developed in [25] achieved a higher realized gain of −0.78 dB and a radiation efficiency of 40; it also provided a long reading distance of 11 m. However, this antenna has a four-layer structure and uses the foldedpatch technique. Such designs have a complex fabrication process and are more difficult to tune optimally.…”

“…The proposed antenna was designed with a compact and lowcost structure, and it did not require multiple vias for the short circuit, extra ground layers, or inner radiation layers. Further, its fabrication procedure was simple and did not require the complicated techniques and multilayer structures of previously proposed antennas [21]- [25]. In addition, the proposed antenna structure could be adjusted easily through the coarse tuning of the width of the shorted inductive plate, I-slot 1, and open and closed slots of the I-shaped patch.…”

“…Studies have miniaturized tag antennas by using multiple shorting stubs in the center and a vertex on the top patch to form inner or ground layers [23] and [24]. However, the combination of multiple shorting stubs and meandered slot lines in the tag structure resulted in poor impedance matching between the antenna and the microchip; this, in turn, reduced the power transmission coefficient to less than 0.7 and the achievable reading range to less than 5 m. Another study [25] significantly improved the power transmission coefficient to approximately 99.7% and achieved a large read distance of at least 7 m. However, similar designs have been described in [21]- [24]. Further, these tags required more ground planes or inner radiating planes; this complicated the structure and increased the total size of the tag antennas.…”