A dual circularly polarized horn antenna, which employs a chiral metamaterial composed of two-layered periodic metallic arc structure, is presented. The whole antenna composite has functions of polarization transformation and band-pass filter. The designed antenna produces left-handed circularly polarized wave in the band from 12.4 GHz to 12.5 GHz, and realizes right-handed circularly polarized wave in the range of 14.2 GHz-14.4 GHz. Due to low loss characteristic of the chiral metamaterial, the measured gains are only reduced by about 0.6 dB at the above two operation frequencies, compared with single horn antenna. The axial ratios are 1.05 dB at 12.45 GHz and 0.95 dB at14.35 GHz.