In this paper, a novel dual-band circular polarization was proposed, which converts the incident linear polarization electromagnetic waves into left-handed and right-handed circularly polarized waves at 22. 1 ~ 24. 2 and 30. 1 ~ 33. 2 GHz, respectively. These two channels precisely cover the two observation channels of (23. 8 ± 0. 2) and (31. 4 ± 0. 1) GHz in atmospheric remote sensing. The insertion loss in the remote sensing observation channel is less than 1 dB, and the axial ratio is better than 1. 26. It fully meets the detection requirements of the existing atmospheric remote sensing in two observation channels of (23. 8 ± 0. 2) and (31. 4 ± 0. 1) GHz. For designing this circular polarizer, the circuit resonance theory was used to construct the passband, and preliminary analysis was conducted through equivalent circuits. It is optimized by the electromagnetic simulation software to complete the design.