Meandered cross-shaped slot circularly polarised antenna for handheld UHF RFID reader

Abstract

A compact meandered cross-shaped slot circularly polarized antenna for ultra high frequency (UHF) band radio frequency identification (RFID) reader applications is presented. Circularly polarized radiation is realized by introducing a slot on the diagonal axis of a square patch. Four different slot shapes are entrenched on one of the diagonal axes of the square patch for circularly polarized radiation and compared to the fixed overall volume of the antenna. The overall size of the antenna is reduced by increasing the perimeter of a slot within one quadrant of the patch. The meandered cross-shaped slot circularly polarized antenna is compact when compared with circular-, square- and cross-shaped slot circularly polarized antennas. Diagonally symmetric two- and four-meandered cross-shaped slot antennas are studied for further size miniaturization. Measured 3 dB axial ratio bandwidth of around 6 MHz with more than 2 dBic boresight gain and 10-dB reflection coefficient of 22 MHz is obtained with circularly polarized meandered cross-shaped four slot antenna. Size of the antenna is 0.189 λ 0 × 0.189 λ 0 , where λ 0 is the operating wavelength at 915 MHz. © 2018