Dual Band Circularly-Polarized Crossed-Dipole Antenna for RFID Applications

For handheld RFID scanner applications, a compact dual band antenna operating in 0.915-GHz and 2.45-GHz RFID bands with circular polarization is proposed. Two folded dipoles are designed to produce two bands. The circular polarization is attained by the ring delay lines and stubs. The antenna with an overall dimension of 80×80×1.6mm
³
possess an impedance bandwidth of 186 MHz (912-1098 MHz) and 952 MHz (2.17-3.12GHz) along with 3-dB axial ratio bandwidth of 47.5 MHz (905-952.5 MHz) and 227.5MHz (2.35-2.58 GHz) within two bands, respectively. The peak gain of 7.53 dBic within the CP bandwidth is achieved by the antenna.