The development of multibeam antenna technology has led to significant increases in the capacity of communications satellites. Conventionally, reflector antennas have been the primary candidates for such systems, and their designs have matured to meet increasing requirements. Recent advances in printed-circuit antennas, and the advent of gallium arsenide monolithic microwave integrated circuits (CaAs MMIC) have enhanced the feasibility of using active phased arrays as multibeam antennas on-board satellites, and as alternatives to (or feeds to) reflectors. These technologies will improve operational flexibility, increase overall capacity, and make better use of scarce mass and power resources of the satellite. The evolution of satellite antennas over the past quarter of a century is presented. Five major areas of advances in communications satellite antenna technology are reviewed: single offset reflectors with feed arrays, shaped reflector systems, active phased arrays, phased-array-fed dual reflector systems, and lightweight feed elements. Examples are given of existing systems and of the ongoing development of new technologies. © 1990 IEEE