Dual-Band Circularly Polarized Cavity-Backed Crossed-Dipole Antennas

In this letter, a novel dual-band circularly polarized cavity-backed crossed-dipole antenna is proposed. Complementary split-ring resonators (CSRRs) are loaded along both the arms of double-sided printed crossed dipoles along with vacant quarter-printed rings to achieve dual-band circularly polarized operation. Cavity-backed reflector is employed in the antenna to achieve unidirectional pattern with high front-to-back-lobe ratio ( > 25 dB), wide circularly polarized radiation beamwidth, and high gain in both frequency bands. The impedance and axial-ratio bandwidths in both bands are also considerably improved by the cavity backing. The proposed dual-band crossed-dipole antenna has two operating bands centered at 1.81 GHz (impedance bandwidth 22.4%, axial-ratio bandwidth 6.6%) and 2.67 GHz (impedance bandwidth 33%, axial-ratio bandwidth 10.1%), respectively .