Lessons Learned from a Deployment Mechanism for a Ka-band Deployable  Antenna for CubeSats  Jonathan Sauder*, Nacer Chahat*, Richard Hodges*, Eva Peral* Yahya Rahmat-Samii**  and Mark Thomson+ Abstract  The Ka-band parabolic deployable antenna (KaPDA) is a 0.5-meter-diameter antenna that fits in a tiny,  CubeSat compatible 10 cm by 10 cm by 16 cm volume. The design evolved from a rough concept in an  R&D proposal to a fully flight-qualified design, scheduled for launch in May of 2018, in a timeframe of just  4 years. This paper focuses on key lessons learned on maintaining precision through structural depth, the  use of fixtures, additive manufacturing for fabrication, the design of robust, deterministic mechanisms, and  the dangers of friction and press fits.   Introduction  CubeSats have undergone an exciting evolution over the past decade. From being considered an academic  exercise, they have grown to the point of obtaining real science data and are providing commercially viable  business opportunities [1]. As the technology has increased in capability, so have the needs in the areas  of power, propulsion, and communications. One critical need in the area of communications is high gain  antennas, and specifically deployable antennas given the CubeSat’s small size. Deployable antennas  would enable communication at much higher data rates and radar instruments in small packages. Operating  at a high frequency, like Ka-band, further increases the amount of data that can be transmitted. However,  a deployable Ka-band parabolic antenna makes for a very challenging mechanism design problem. While  there have been individual aspects of the mechanical design published in a series of AIAA conference  papers [2], [3], and details on the radio-frequency design in a series of journal articles [4], [5], this paper  focuses on key mechanism lessons learned from the KaPDA development.  The seed inspiring this concept started with the Aneas parabolic deployable antenna (APDA) folding rib  parabolic mesh antenna used on the University of Southern California’s Information Sciences Institute  (USC/ISI) Aneas spacecraft [6]. The Aneas was launched in 2012, and the folding rib geometry illustrated  a robust deployment sequence that has been used on larger antennas, like some of Harris’s Unfurlable  Antennas [7]. However, the APDA was designed to operate at S-band, whereas Ka-band brings an entirely  new set of requirements. Therefore, while a similar general architecture was used, the RF design and each  the mechanisms were completely re-engineered.   Requirements for KaPDA and Design Overview  Requirements  The goal of KaPDA was to create a new capability for CubeSats, to enable high-speed data rates from  deep space. Data rates in a communications link budget depends on a number of things, including power  of the transmitter, receiver sensitivity, ground antenna configuration, frequency of operation, and satellite  antenna configuration. The goal for this task was to improve data rates through the satellite antenna,  specifically to achieve a gain of 42 dBi. The three ways of accomplishing this are to 1) have a high frequency  antenna 2) operate with high efficiency and 3) a large diameter.   *Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA ** University of California Los Angeles, Los Angeles, CA +Northrop Grumman Astro Aerospace, Carpenteria, CA Proceedings of the 44th Aerospace Mechanisms Symposium, NASA Glenn Research Center, May 16-18, 2018 © 2018 All Rights Reserved. Government sponsorship acknowledged. 

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