Circular Polarized Antenna with Rotationally Positioned Microstrip Structures For UHF RFID Applications

With the use of wireless communication and the industry 4.0 revolution, RFID technology integration in production has increased. The large-scale preference of RFID systems is both cost-effective and significantly increasing production. It is an innovation that provides convenience for large production facilities such as product control, in-plant tracking, storage, inventory operations. In this paper, a compact circularly polarized (CP) reader antenna is presented for ultra-high frequency (UHF) radio frequency identification (RFID) applications. The proposed antenna consists of a circularly slotted ground plane and folded plus-shaped structures with vertical and horizontal positions. Microstrip line feeding technique is used in the vertically folded plus-shaped structure positioned on the front surface. The antenna has a 10 dB return loss bandwidth of 80 MHz (840-920) and a 3 dB axial ratio bandwidth of 20 MHz (855-875). Theproposed antenna has dimensions of 75 × 75 × 1.6 mm3 . The size advantage of the single-layer and singlefed structure enables its applicability in portable systems.