CubeSats provide the ability to conduct relatively inexpensive space missions. Over the past several years, technology and launch opportunities for CubeSats have exploded, enabling a wide variety of missions. However, as instruments become more complex and CubeSats travel deeper into space, data communication rates become an issue as highlighted by a recent NASA centennial challenge proposal. A Ka-band highgain antenna would provide a ≈100× increase of data communication rates over an S-band high-gain antenna, and a ≈10,000× increase over an X-band patch antenna of the same input power, enabling high-rate data communication from deep space or the use of dataintensive instruments from low Earth orbit (LEO).
A promising approach for providing a Ka-band high-gain antenna is the use of a parabolic deployable antenna (PDA). While a handful of PDA concepts for CubeSats have been developed, they all operate at a lower Sband data rate. Perhaps the most robust of the current concepts, and the only one to have flown, is the University of Southern California’s Information Science Institute’s (USC/ISI) ANEAS PDA. The design uses a folding rib architecture where ribs deploy like an umbrella. Mesh between each rib provides a reflective surface. It was determined to use the same deployment architecture for the Ka-band parabolic deployable antenna (KaPDA).
To design KaPDA, JPL first collaborated with USC/ISI to understand and characterize the ANEAS antenna flight spare. Characterization showed the antenna needed to be entirely redesigned for Ka-band operation, although the folding rib architecture could be maintained. A Cassegrainian dual reflector design with a smooth wall horn feed and telescoping waveguide was selected, instead of the prime focus single reflector that ANEAS utilized. To hold the surface accuracy required by Ka-band, the antenna was designed with deep ribs, precision hinges, and a denser, stiffer mesh. The ribs are deployed by cables, actuated by a slowly inflating bladder, and then latched into place. Using a bladder reduces the whiplash that occurs in many other antenna designs where strain energy or springs are used for deployment. The sub-reflector is supported by a composite structure that telescopes along the horn during a spring-powered deployment.
RF design and a complementary mechanical deployment mechanism design have been completed. The antenna is 0.5 meter in diameter and stows in 1.5U (10 × 10 × 15 cm3). RF simulations show that, after losses, the antenna will achieve over 42 dB gain, which is above 50% efficiency. At the time of writing, a prototype was under development and slated for completion in early 2015, and a flight-ready antenna was scheduled to be built by the end of 2015.
This work was done by Mark W. Thomson, Richard E. Hodges, Nacer E. Chahat, and Jonathan Sauder of Caltech; and Yahya Rahmat-Samii of the University of California, Los Angeles for NASA’s Jet Propulsion Laboratory.
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