UCLA

The advent of low-cost and lightweight CubeSats has opened up new possibilities to realize the Internet of Space (IoS), a vision that aims to establish a constellation of CubeSats in space to provide global network access. A key challenge for IoS realization is the development of beam steerable antennas that can meet the gain, bandwidth, and polarization requirements for IoS while complying with the small form factor of CubeSats. This work addresses this challenge by proposing innovative synthesis and implementation methods for reflectarrays and transmitarrays to empower low-profile wideband circularly-polarized (CP) beam steerable antennas. Two unique steerable antenna architectures are presented. The first design is a K-band mechanically steerable Risley prism antenna (RPA) constructed by two co-axially placed panels, i.e., a gradient-phase feed array (GPFA), and a gradient-phase transmitarray (GPTA). The in-plane rotation of the two panels creates beam scan that covers 0� - 360� in azimuth and 0� - 60� in elevation. To improve the CP bandwidth, a hybrid-phasing method is applied to design the GPFA, and an S-ring element unit cell is designed for the GPTA. The second design is an electronically steerable reflectarray antenna. Each unit cell can implement switches to reconfigure the connections among multiple Archimedean spiral arms, creating ``element rotation'' that leads to geometrically dependent CP phase shift. This allows the reflectarray to achieve wideband CP beam steering without any moving parts. Both antennas have been validated through prototypes and measurements to demonstrate their beam scanning capability and bandwidth potentials for CubeSat applications. Besides, a generalized design methodology for switch-reconfigured unit cells (SRUC) to achieve the maximum phase resolution is established. It applies binary particle swarm optimization (BPSO) algorithm to optimize the topology of pixelated unit cells with embedded switches. Unconventional linearly-polarized (LP) and CP 2-switch 4-state SRUC for K-band beam steerable reflectarrays have been designed and thoroughly validated. Lastly, the novel charge-programmed multi-material (CPMM) additive manufacturing technology is applied to innovate antenna design and fabrication. Several ultra-lightweight CP transmitarrays achieving order-of-magnitude weight reduction and a compact CP horn antenna with uniquely designed 3D structures have been manufactured and measured. This dissertation addresses the cutting edges of CubeSat beam steerable antennas from several aspects, including the fundamental principles, synthesis methods, antenna architectures, and manufacturing methods.