Retrodirective Antenna Arrays

The followin sections are excerpted from Justin W. Long's NASA Science Technology Research Fellowship proposal, "IMPROVING COMMUNICATION THROUGHPUT WITH RETRODIRECTIVE ARRAYS FOR CUBESAT APPLICATIONS". The fellowship has been funded, and this document is not available online. Please contact SSEP for further information about the project.

Purpose

The purpose of this project is to investigate and propose solutions for the development of retrodirective arrays (RDA) for CubeSat applications. As an end result, this project aims to improve information throughput with the design of a RDA that meets the strict power and size requirements of CubeSats and other small satellites. This is directly related to the goal of Technology Area (TA) 5.2 of the NASA Technology Roadmaps:

Enable higher data rates and data throughput for near-Earth and deep-space to ground communications.

More specifically, this project aims to meet TA 5.2.6:

Develop deployable antennas or antenna arrays that are efficient and can be pointed.

The retrodirective antenna array provides autonomous steering of the beam pattern so that the antenna points itself in the direction of arrival (DOA) of a signal source. This will improve satellites antenna pointing abilities without requiring highly accurate attitude determination and control. The end result is an improved communication link without any additional power requirements. This technology has already been implemented on a larger magnitude, and so the purpose of this project will be to scale the technology down to meet the needs of smaller satellites.

Project Objectives

  1. Investigate current RDA architectures for implementation on a CubeSat platform.
  2. Investigate the use of digital signal processing for new RDA architectures.
  3. Investigate RDA implementation for Ka and Ku frequency bands.
  4. Design a RDA architecture that meets standard CubeSat design requirements.
  5. Prototype the RDA designed in objective 4.

Summary

The purpose of this project will be to investigate and propose solutions for the development of retrodirective arrays (RDA) for CubeSat applications. As an end result, this project aims to improve information throughput with the design of a RDA that meets the strict power and size requirements of CubeSats and other small satellites. This project is a part of a larger ongoing research and development program for advanced CubeSat communications systems involving multiple thesis projects at the University of Alaska Fairbanks.

The retrodirective antenna array provides autonomous steering of the beam pattern so that the antenna points itself in the direction of arrival (DOA) of a signal source. This will improve satellites antenna pointing abilities without requiring highly accurate attitude determination and control. The end result is an improvement in information throughput by optimizing the power received at the ground station. This technology has already been implemented on a larger scale, and so the purpose of this project will be to miniaturize the technology to meet the needs of smaller satellites. RDAs offer the potential for increasing received power during satellite downlink and improved information throughput. This is directly relevant to NASA technology area 5.2.6, and has widespread applications beyond the CubeSat platform.

Numerous challenges and limitations must be overcome before RDA technology is ready to be functionally implemented on a CubeSat. The primary objective of this project is to optimize the design and prototype a functional RDA architecture for CubeSat platforms.