DESIGN OF SPIRAL ANTENNA ARRAY AND COMMUNICATION SYSTEM FOR X-BAND CUBESAT IN LUNAR ORBIT by KATELYN ROSE ISBELL YANG-KI HONG, COMMITTEE CHAIR STEPHEN J. YAN SEVGI GURBUZ RICHARD D. BRANAM A THESIS Submitted in partial fulfillment of the requirements for the degree of Master of Science in the Department of Electrical and Computer Engineering in the Graduate School of The University of Alabama TUSCALOOSA, ALABAMA 2020 Copyright Katelyn Rose Isbell 2020 ALL RIGHTS RESERVED ABSTRACT Recent advancements in the design of CubeSats, a type of nanosatellite, have allowed missions to include lunar, asteroid, and planetary destinations. Communication for deep space CubeSats poses new challenges for researchers in terms of transmitting and receiving range capabilities, reliability, and power and size limitations. An X-band downlink communication system is designed to address link budget and CubeSat system requirements for a lunar orbit. An Archimedean spiral antenna array backed by a novel sloped wall cavity and fed with a Klopfenstein impedance taper and power splitter is designed and characterized. An X-band transmitter is designed to fulfill the link budget and is analyzed for RF performance. ii DEDICATION This thesis is dedicated to my parents for their endless support. iii LIST OF ABBREVIATIONS AND SYMBOLS ADS Advanced Design System AR Axial Ratio AR00 Axial Ratio at Boresight ARBW Axial Ratio Beam Width ASA Archimedean Spiral Antenna BER Bit Error Rate BPSK Binary Phase Shift Keying CBC Conventional Backing Cavity COTS Commercial Off-the-Shelf D Distance in Link Budget DAC Digital-to-Analog Converter DSN Deep Space Network DSP Digital Signal Processing Eb Energy Per Bit EM-1 Exploration Mission-1 ESA European Space Administration FCC Federal Communications Commission FPGA Field Programmable Gate Array FQPSK Feher Patented Quadrature Phase-Shift Keying iv FSPL Free Space Path Loss GMSK Gaussian Minimum Shift Keying GR Receiving Antenna Gain GT Transmitting Antenna Gain HFSS High Frequency Structure Simulator HGA High Gain Antenna HPBW Half Power Beam Width I In-Phase INSPIRE Interplanetary Nano-Spacecraft Pathfinder in Relevant Environment JPL Jet Propulsion Laboratory LEO Low Earth Orbit LGA Low Gain Antenna MarCO Mars Cube One MGA Medium Gain Antenna N0 Noise Spectral Density NASA National Air and Space Administration OQPSK Offset Quadrature Phase Shift Keying P-POD Poly-Picosatellite Orbital Deployer PR Receiving Power PSK Phase-Shift Keying PT Transmitting Power Q Quadrature QPSK Quadrature Phase Shifting Keying v R Data Rate RF Radio Frequency RG Realized Gain RG00 Realized Gain at Boresight RX Receive SCRAM Space Communication Rates At Multi-Gbps SFDR Spurious-Free Dynamic range SNR Signal to Noise Ratio SQPSK Staggered Quadrature Phase-Shift Keying SWBC Sloped-Wall Backing Cavity TS System Noise Temperature TX Transmit UHF Ultra-High Frequency VHF Very High Frequency VNA Vector Network Analyzer Z0 Initial Impedance Zin Input Impedance ZL Load Impedance εeff Effective Relative Permittivity εr Relative Permittivity Г Reflection Coefficient vi ACKNOWLEDGEMENTS I would like to thank my advisor and committee chair, Dr. Yang-Ki Hong for his guidance and support for my graduate and undergraduate research careers. I would also like to thank my committee members Dr. Stephen J. Yan, Dr. Sevgi Gurbuz, and Dr. Richard D. Branam for their help in my completion of this thesis. I am also grateful to my fellow researchers in the Magnetic Materials and Devices lab for their assistance: Dr. Woncheol Lee, Nikolaus Luhrs, Hoyun Won, Minyeong Choi, Briana Bryant, Jonathan Platt, and Leo Vanderburgh. vii CONTENTS ABSTRACT .................................................................................................................................... ii DEDICATION ............................................................................................................................... iii LIST OF ABBREVIATIONS AND SYMBOLS .......................................................................... iv ACKNOWLEDGEMENTS .......................................................................................................... vii LIST OF TABLES ......................................................................................................................... xi LIST OF FIGURES ...................................................................................................................... xii CHAPTER 1: INTRODUCTION ................................................................................................... 1 1.1 Motivation ............................................................................................................................. 1 1.2 Contributions ......................................................................................................................... 1 1.3 Organization .......................................................................................................................... 2 1.4 Publications ........................................................................................................................... 2 CHAPTER 2: LITERATURE REVIEW ........................................................................................ 5 2.1 History of CubeSats .............................................................................................................. 5 2.2 The CubeSat Standard ........................................................................................................... 7 2.3 CubeSats for Deep Space ...................................................................................................... 8 CHAPTER 3: SYSTEM OVERVIEW ......................................................................................... 12 3.1 Mission ................................................................................................................................ 12 viii 3.2 Proposed System ................................................................................................................. 12 3.3 Modulation Selection .......................................................................................................... 14 3.4 Frequency Band Selection ................................................................................................... 16 3.5 Link Budget ......................................................................................................................... 16 3.6 Bandwidth ........................................................................................................................... 19 CHAPTER 4: ANTENNA DESIGN ............................................................................................ 21 4.1 Antenna Characteristics....................................................................................................... 21 4.2 Archimedean Spiral ............................................................................................................. 22 4.2.1 Theory of Operation ..................................................................................................... 22 4.2.2 Design .......................................................................................................................... 24 4.3 Microstrip Balun ................................................................................................................. 26 4.3.1 Theory of Operation ..................................................................................................... 26 4.3.2 Design .......................................................................................................................... 27 4.3.3 Fabrication and Measurement ...................................................................................... 33 4.4 Backing Cavity .................................................................................................................... 36 4.4.1 Theory of Operation ..................................................................................................... 36 4.4.2 Design .......................................................................................................................... 37 4.5 Spiral Array ......................................................................................................................... 41 4.5.1 Design .......................................................................................................................... 41 4.5.2 Proposed 6x6 Spiral Array ........................................................................................... 43 ix 4.6 Power Splitter ...................................................................................................................... 43 4.6.1 Theory of Operation ..................................................................................................... 43 4.6.2 Design .......................................................................................................................... 44 4.7 Antenna Characterization .................................................................................................... 49 4.7.1 Fabrication Process ...................................................................................................... 49 4.7.2 Measurement Process................................................................................................... 49 4.7.3 Spiral Antennas ............................................................................................................ 51 4.7.4