Miniaturized Circularly Polarized Vicsekcross-Shaped Slot Antenna for UHF-RFID Reader Handset Applications

In this research, a circularly polarized antenna employing fractal slot geometry is proposed for UHF-RFID handset reader application. The proposed antenna consists of vicsekcross-shaped slot etched at diagonal axis to achieve circular polarization with a coaxial feed placed 45 degrees with respect to the slot. The evolution of Vicsekcross shaped fractal slot is developed in different iteration stages for achieving wide impedance bandwidth covering U.S. UHF-RFID band with good axial ratio bandwidth performance. The single slotted reader antenna was investigated first followed by multi-slot antenna for size miniaturization, impedance bandwidth and axial ratio bandwidth performance. The impedance bandwidth and axial ratio bandwidth of the designed antenna were observed to be 25 MHz (903-927 MHz) and 7 MHz (911-917 MHz), respectively. Additionally, the designed antenna exhibited LHCP with a maximum measured gain of 2.9 dBic. The size of the final Vicsekcross-shaped four slot CP reader antenna is compact with dimensions of 57 x 57 x 1.6 mm(3).

Automated summary

In this study, a circularly polarized antenna employing fractal slot geometry is proposed for UHF-RFID handset reader application. The antenna achieves circular polarization by using a Vicsekcross-shaped slot etched at diagonal axis and a coaxial feed placed at 45 degrees. By evolving the Vicsekcross-shaped fractal slot in different iteration stages, wide impedance bandwidth and good axial ratio bandwidth performance for the U.S. UHF-RFID band are achieved. The designed antenna has an impedance bandwidth of 25 MHz (903-927 MHz) and an axial ratio bandwidth of 7 MHz (911-917 MHz). Additionally, the antenna exhibits left-hand circular polarization (LHCP) with a maximum measured gain of 2.9 dBic. The final Vicsekcross-shaped four slot CP reader antenna is compact in size, measuring 57 x 57 x 1.6 mm³.