In this paper, a high-gain circularly polarized (CP) antenna array is proposed for inter-satellite link (ISL) applications in low Earth orbit (LEO) satellite communication systems. The proposed CP antenna architecture enables high directivity while maintaining compatibility with beamforming integrated circuits (BFICs), making it a promising candidate for ISL payloads. Furthermore, the antenna design can be readily scaled to larger arrays by extending a 2×2 sub-array unit. Each sub-array consists of four multilayer antenna elements arranged in a sequentially rotated configuration, driven by a single 4-channel BFIC to realize robust CP radiation. The proposed structure adopts a low-profile air-gapped multilayer configuration to further enhance the CP gain, axial ratio (AR), and cross-polarization discrimination (XPD). To validate the performance of the active integrated antenna, a 4×4 left-hand circular polarization (LHCP) array was implemented with four 4-channel BFICs and tested within the 26.7–27.5 GHz ISL frequency band. The measured 10-dB impedance bandwidth of the fabricated 4×4 array were 6.3%. Additionally, normalized pattern confirmed stable CP with an XPD level achieved at a minimum of 33 dB at 27 GHz.
