Satellite communication (Satcom) services are used worldwide for voice, data, and video links due to various appealing features. Parabolic reflector antennas are typically used to serve a cost effective scheme for commercial applications. However, mount degradation, roof sag, and orbital decay motivate the need for beam steering. Limited scan range beam steering opens a third option for electronic beam steering with lower cost than full aperture phased arrays and higher tracking speed and accuracy than mechanical-only steering.Multiple high efficiency passive patch array feeds were designed, fabricated, and measured, including a 2x2 MSA array, a stacked shorted annular patch antenna, and an SIW-fed hexagonal array feed based on PTFE material, achieving performance comparable to a horn feed. For multiband dual polarization applications, passive MSA feed solutions are also provided. Multiple MSA array feeds with high isolation were designed for dual band dual polarization applications. More functionality can be realized with multi-layer PCB techniques for complex communication scenarios.Limited scan range electronic beam-steering with a parabolic reflector fed by an active array feed which only needs gain control was demonstrated experimentally, leading to a low cost and effective solution for active beam scanning. A cost-effective flat-panel phased array with limited scan range electronic beam-steering was proposed by tiling high efficiency 4x4 passive subarrays and performing beam scanning at the tile level. The sidelobe issue was also investigated to comply with the pattern mask requirement set by FCC.To enable better use of circularly polarized (CP) MSAs for electronically beam-formed antenna systems, the impact of mutual coupling on the performance of high-sensitivity dual-polarized receivers for satellite communications applications was analyzed. A new analysis method for intrinsically dual-CP MSAs based on an equivalent circuit model and Jones matrices was proposed and validated to overcome the port isolation challenge. The model provides accurate estimates of impedances and S-parameters, as well as field parameters such as axial ratio. The feasible region for XPI and impedance mismatch factor is found for dual CP antennas. The circuit model enables multiple useful applications. Effective decoupling and matching schemes was proposed and demonstrated, leading to a high isolation, good match, and wide AR bandwidth dual CP MSA for satellite communications.