Inflatable membrane antennas for small satellites

CubeSats have been growing in capability and are being considered for more challenging mission objectives. A significant challenge towards this is limited data downlink rates available from CubeSat communication systems. This is due to volume and mass constraints imposed by CubeSat reference standards. The size of the platform also places constraints on the power system on-board. To maintain high transmit data-rates from CubeSats, high gain antennas (HGA) have emerged as a key technology. Conventional HGA technology for small satellites are restricted to reflect-arrays and mechanical linkage systems. Such systems do not package very efficiently into available payload volumes on CubeSats. Further, the complexity of the deployment mechanism introduces multiple points of potential failure. Hence such systems are not easily scalable to larger sizes needed for greater capability. FreeFall Aerospace along with the University of Arizona is focusing on the development of inflatable spherical antenna systems for small satellites. These systems are comprised of membrane spheres with a partially reflective surface inflated pneumatically from sizes ranging from half to 2 meters. The metallized portion of the sphere serves as a spherical reflector which, together with a custom line feed, forms a high gain, electronically steerable antenna system. In the present work, we describe our development of deployment and packaging systems for inflatable antennas from CubeSats ranging in size from 6U and above. The focus of our approach has been on mechanical simplicity of deployment and scalability over a range of antenna sizes. The inflation system has been designed to prevent over-pressurization of the membrane. Packaging of the membrane has been tested with multiple folding patterns aimed at maximizing packing efficiency and minimizing wrinkles on the membrane's reflective surface. Our work presents a mechanically simple membrane antenna system that can be scaled over varying small satellite sizes as a high gain, high bandwidth tele-communication system.