Retrodirective phased array antenna for nanosatellites

Thesis (M.S.) University of Alaska Fairbanks, 2019This thesis presents a S-band phased array antenna for CubeSat applications. Existing state-of the-art high gain antenna systems are not well suited to the majority of CubeSats, those that fall within the 1U (10 cm x 10 cm x 10 cm) to 3U (10 cm x 10 cm x 30 cm) size ranges and in Low Earth Orbit (LEO). The system presented in this thesis is designed specifically to meet the needs of those satellites. This system is designed to fit on the 1U face (10 cm x 10 cm) of a CubeSat and requires no deployables. The use of beamforming and retrodirective algorithms reduces the pointing requirements of the antenna, easing the strict requirements that high gain antennas typically force on a CubeSat mission. Additionally, this design minimizes volume and uses low cost Commercial-off-the-Shelf (COTS) parts. This thesis discusses the theoretical background of phased array theory and retrodirective algorithms. Analysis are presented that show the characteristics and advantages of retrodirective phased antenna systems. Preliminary trade studies and design analyses show the feasibility and expected performance of a system utilizing existing COTS parts. The preliminary analysis shows that an antenna system can be achieved with ≥8.5 dBi of gain, 27dB of transmitted signal gain, 20% Power Added Efficiency (PAE) within a 1 W to 2 W power output, and an 80° effective beamwidth. Simulation results show an example antenna array that achieves 8.14 dBi of gain and an 82° effective beamwidth. Testing results on a prototype of the front-end electronics show that with minimal calibration, the beamforming and scanning error can be reduced to 5°. The power consumption and signal gain of the electronics is also verified through testing. The CubeSat Communications Platform, a CubeSat mission funded through the Air Force Research Laboratory is in Phase A design to demonstrate this antenna system, along with other experimental payloads. This thesis includes a discussion of interface control, mission requirements, operations, and a recommended experiment sequence to test and verify the antenna system on orbit.Alaska Space Grant Program, NASA Space Technology Research Fellowship (80NSSC170185

Against Certification

Certification is the process whereby federal courts, confronted by an open question of state law in federal litigation, ask the relevant state high court to decide the state law question. If the state high court chooses to answer, its statement of state law stands as the definitive declaration of the law on the disputed point. The case then returns to the certifying federal court, which resolves any remaining issues, including federal questions, and then issues a mandate. Although a wide range of academic commentators and jurists support certification as an example of respect for state autonomy, this Article shows that in both practice and theory certification does not reflect real comity. Rather, certification is an example of dual federalism, the view that state and federal law ought to be isolated into separate spheres of jurisprudence. For federal courts to show genuine respect for state law, they should stop treating it as foreign and decide open state law questions without certification