A broadband circularly polarized (CP) S-band antenna array for CubeSat technology was proposed. The proposed CP antenna array comprised of 2 × 2 rectangular-shaped ring patches and sequentially rotated feeding structure. Besides, the sequentially rotated feeding structure is utilized to match impedance. This antenna is made of single-layered Roger RT5880 substrate. The simulation results at 2 GHz achieved IBW of 81% (1.3 - 2.92 GHz) and ARBW of 25% (1.85 - 2.35 GHz). The optimal RHCP gain is 4.69 dBic at 2.25 GHz. The half-power beamwidth at 2 GHz is 71.51°. The radiation patterns are RHCP characteristic. The proposed CP S-band antenna array with sequentially rotated feeding structure is deployed with the CubeSat platform, resulting in the proposed CP antenna array befitting CubeSat technology.
