A capacitively-loaded loop antenna for UHF near-field RFID reader applications

A capacitively-loaded loop antenna for UHF near-field RFID reader applications In this work, we present a compact capacitively-loaded loop antenna for Ultra-High Frequency (UHF) near-field radio frequency identification (RFID) reader applications. The antenna structure is composed by folded-dipole loop structure with two C-arms and miniaturized to small size of 40 × 36 × 1.6 mm3 forRFID applications. Our bandwidth measurement of antenna prototype is 10.5 MHz from 865-875.5 MHz with reflection coefficient less than 10 dB, which covers all of Europe RFID Band (865-868 MHz). Furthermore, a capacitive loading through two C-arms is created inside the loop antenna and has an effect of increasing the electrical length of the antenna structure. Therefore, the proposed antenna can be dedicated to different UHF RFID bands by varying the C-arm parameters. The measured reading capability of our antenna is up to 7 cm for near-field RFID Tag, and our measurements show this antenna is suitable for UHF near-field RFID reader applications.