A Millimeter-Wave Dual-Band Dual-Circularly Polarized Element Antenna

In this paper, a single-fed dual-band dual circularly polarized (CP) antenna element on account of the spiral antenna is designed. By employing two spiral structures of Archimedes rotating in different directions, dual-band dual CP character is achieved. This element produces left-hand circularly polarized (LHCP) and right-hand circularly polarized (RHCP) in low and high frequency bands, respectively. According to the simulation results, the antenna element achieves 16.6% and 14.4% impedance bandwidths in the lower and higher bands, respectively. The axial ratio (AR) bandwidths are 9% and 7.2% for the lower and higher bands, respectively.