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Title:Pattern reconfigurable reflectarray for cubesat applications
Author(s):Srivastava, Sakshi
Director of Research:Bernhard, Jennifer T
Doctoral Committee Chair(s):Bernhard, Jennifer T
Doctoral Committee Member(s):Schutt-Aine, Jose E; Makela, Jonathan J; Gong, Songbin
Department / Program:Electrical & Computer Eng
Discipline:Electrical & Computer Engr
Degree Granting Institution:University of Illinois at Urbana-Champaign
Degree:Ph.D.
Genre:Dissertation
Subject(s):Reflectarray
Pattern Reconfiguration
CubeSat
Abstract:With an increasing presence among educational, commercial and governmental agencies, CubeSats are one of the more affordable options to explore space, especially in comparison to their larger counterparts. This has been enabled by their small form factor, cost-effective design and ability to be launched as secondary payloads. Since CubeSats typically reside in the Low Earth Orbit (LEO), they get a limited time to communicate with the ground station. This coupled with low data rates can restrict the amount of data shared from the CubeSat to the ground station. One potential solution to this problem is to employ high gain antennas. However, to have a sustained high data rate during a pass the antenna must have pattern reconfiguration so that a high gain beam can be maintained between the CubeSat and the ground station. A brief motivation for the use of high gain antennas for CubeSats is presented. It leads to a discussion about reflectarrays and their current use as CubeSat antennas. However, reflectarrays for CubeSats like Mars Cube One do not have pattern reconfiguration. A novel reflectarray design which implements pattern reconfiguration by mechanically manipulating the reflector aperture is proposed. A typical reflectarray consists of a feed antenna and an aperture. Aperture efficiency analysis was conducted to develop design specification for the feed as well as other aspects of the feed design process are discussed. Additionally, details about the aperture design are provided including a reflection phase analysis for aperture elements. With the baseline reflectarray design in place, two different techniques of aperture folding were studied for their impact on the radiation pattern. Using one of these two techniques a mapping between aperture fold angles and beam gain and location was generated. A composite radiation pattern is presented for such a reconfigurable antenna. Moreover, a discussion about circularly polarized wave from the reflectarray and its dependence on the size and the orientation of the feed is presented. Fabrication limitations were taken into account and the design was updated to achieve circular polarization and enable ease of fabrication. Considerations about the reflectarray being a CubeSat antenna were addressed and its behavior in the presence of a CubeSat chassis model was analyzed. Additionally, the speed of aperture reconfiguration was determined and the overall effect of pattern reconfiguration on net data exchanged was calculated. Lastly, the reflectarray was fabricated, measured and the results were analyzed in conjunction with the results from simulation.
Issue Date:2021-08-05
Type:Thesis
URI:http://hdl.handle.net/2142/114038
Rights Information:Copyright 2021 Sakshi Srivastava
Date Available in IDEALS:2022-04-29
Date Deposited:2021-12


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