  AcubeSAT is an open-source CubeSat mission aiming to explore the effects of
microgravity and radiation on eukaryotic cells using a compact microfluidic LoC
platform. It is developed by SpaceDot, a volunteer, interdisciplinary student
team at the Aristotle University of Thessaloniki and supported by the "Fly Your
Satellite! 3" program of the ESA Education Office. The scientific data of the
mission is comprised of microscope images captured through the on-board
integrated camera setup. As the total size of the payload data is expected to
be close to 2GB over 12 months, a fast and efficient downlink fulfilling the
restrictive power, cost and complexity budgets is required. Currently, there is
no open-source communications system design which fully supports these specific
constraints, so we opted to develop our own solutions. The antenna system
underwent multiple iterations as the design matured, a process highly aided by
the feedback received from the ESA experts. The final communications system
configuration consists of an S-band microstrip antenna operating at 2.4GHz and
a UHF deployable antenna, for the payload data and TM&TC respectively, both
in-house designed. In this paper, we will present AcubeSAT's antenna system
iterations that span over 3 years, as well as the rationale and analysis
results behind each. The development decisions will be highlighted throughout
the paper in an effort to aid in the future development of such a low-cost
CubeSat mission communications system.
