Electrostatically figured reflecting membrane antennas for satellites

A design concept is described which may permit the construction of very large high-precision low-mass reflecting antennas for use in space. The concept utilizes electrostatic forces to actively shape a flexible membrane reflector, a method which appears to substantially reduce the number of reflector figure actuators required to achieve a specified reflector surface precision. The concept presents a challenging control problem, however, because the equilibrium reflector figure may exhibit several open-loop Rayleigh-Taylor modal instabilities. The origin and essential elements of this control problem are described and a control approach is proposed. A laboratory demonstration of three successfully stabilized modes on a meter-square membrane is also described which suggests that electrostatically figured satellite antennas with diameters reaching several hundred meters, and ratios of focal length to diameter as small as one, could achieve beamwidths of several arc seconds.