Miniaturized Antenna and Wave Propagation Studies Enabling Compact Low-Power Mobile Radio Networks at Low VHF by Jihun Choi A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy (Electrical and Computer Engineering) in The University of Michigan 2017 Doctoral Committee: Professor Kamal Sarabandi, Chair Professor Anthony Grbic Professor Eric Michielssen Professor Christopher S. Ruf Jihun Choi [email protected] ORCID iD: 0000-0002-9105-9328 © Jihun Choi 2017 This dissertation is dedicated to my family and friends. ii ACKNOWLEDGMENTS It would not have been possible to complete this work without the help and support of the considerate people around me, to only some of whom it is possible to give particular mention here. I would first like to sincerely thank my advisor, Prof. Kamal Sarabandi who has supported me throughout this dissertation with his guidance and encouragement. His persistence and enthusiasm for scientific research serve as a deep source of inspiration in my PhD life. I would also like to take this opportunity to thank Prof. Anthony Grbic, Prof. Eric Michielssen, and Prof. Christopher S. Ruf for their support and advice while serving as my dissertation committee members. Special thanks are given to Dr. Brian M. Sadler and Dr. Fikadu T. Dagefu at the U.S. Army Research Laboratory for their collaboration and suggestions. I would like to extend my gratitude to the former and current members of the Radiation Laboratory and all the other friends I have made at the University of Michigan for their constructive discussions and friendship. I thank Dr. Adib Nashashibi, Dr. Leland Pierce, Dr. Jungsuek Oh, Dr. Young Jun Song, Dr. Meysam Moallem, Dr. Sangjo Choi, Dr. Hamid Nejati, Dr. Jiangfeng Wu, Dr. Hatim Bukhari, Dr. Seungku Lee, Dr. Taehee Jang, Dr. Victor Lee, Dr. Seyit Sis, Dr. Gurkan Gok, Dr. Waleed Alomar, Dr. Yang Liu, Dr. Xiaoyu Wang, Dr. Brian Tierney, Dr. Inyong Kwon, Michael Benson, Mani Kashanianfard, Armin Jam, Amr Ibrahim, Morteza Sheikhsofla, Xiuzhang Cai, Seyed Amjadi, Behzad Yektakhah, Mostafa Zaky, Navid Barani, Michael Giallorenzo, Abdulrahman Alaqeel, Lisa Smith, Milad Zolfagharloo Koohi, Omar iii Abdelatty, Fatemeh Akbar, Amanda Couch, Maryam Salim, Doowhan Jung, Hyeongseok Kim, Sunmin Jang, and Eunseong Moon. I would like to acknowledge the financial support that I have received from the U.S. Army Research Laboratory through collaborative participation in the Microelectronics Center of Micro Autonomous Systems and Technology (MAST) Collaborative Technology Alliance (CTA), National Science Foundation (NSF), Saudi Aramco, and Oak Ridge Associated Universities (ORAU), which made my PhD experience productive and stimulating. Lastly, and most importantly, I place on record, my sincere gratitude and appreciation to my family for their unconditional love, unceasing encouragement, and endless supports, all of which are always the central driving force of my life. To them, I dedicate this dissertation. Jihun Winter, 2017, Ann Arbor. iv TABLE OF CONTENTS DEDICATION. ........................................................................................................ ii ACKNOWLEDGMENTS ..................................................................................... iii LIST OF FIGURES ............................................................................................. viii LIST OF TABLES ............................................................................................... xiv LIST OF APPENDICES .......................................................................................xv ABSTRACT .......................................................................................................... xvi CHAPTER I. Introduction ........................................................................................................... 1 1.1 Motivation ................................................................................................................... 1 1.2 Research Contributions................................................................................................ 3 1.3 Dissertation Overview ................................................................................................. 6 II. Near-Ground Wave Propagation in Complex Environments ....................... 10 2.1 Introduction ............................................................................................................... 10 2.2 Measurement System ................................................................................................. 12 2.2.1 40 MHz Receiver Hardware ............................................................................. 12 2.2.2 Highly Miniaturized Antenna at 40 MHz ......................................................... 14 2.2.3 2.4 GHz Measurement System ......................................................................... 16 2.3 Measurement Scenarios ............................................................................................. 18 2.4 Analysis and Results .................................................................................................. 21 2.4.1 Path Loss Calculations ...................................................................................... 22 2.4.2 Indoor-to-Indoor Channels................................................................................ 22 2.4.3 Outdoor-to-Indoor and Non-Line-of-Sight Outdoor Channels ......................... 26 2.5 Summary .................................................................................................................... 27 v III. A Highly Miniaturized, Lightweight Low-VHF Antenna ............................ 29 3.1 Introduction ............................................................................................................. 29 3.2 Motivation and Design Approach............................................................................ 30 3.3 Simulation and Implementation............................................................................... 32 3.3.1 Design of Rectangular Air-Core Inductors Employed in the Phase Shifter ..... 32 3.3.2 Antenna Design Optimization and Fabrication ................................................. 35 3.4 Measurement and Characterization ......................................................................... 37 3.5 Summary .................................................................................................................. 40 IV. Bandwidth Enhancement of Miniature Low-VHF Antennas ...................... 42 4.1 Introduction ............................................................................................................. 42 4.2 Proposed Approach and Analysis ............................................................................ 43 4.2.1 Proposed Approach ........................................................................................... 43 4.2.2 Antenna Impedance Model ............................................................................... 45 4.2.3 Stability Analysis Based on System Sensitivity ............................................... 46 4.3 Implementation and Discussion ............................................................................... 50 4.4 Summary .................................................................................................................. 53 V. An Effective Characterization Technique for Low-VHF Antennas .............. 54 5.1 Introduction ............................................................................................................. 54 5.2 Electro-Optical Near-Field Measurement ............................................................... 57 5.3 3-D Near-Field to Far-Field Transformation ........................................................... 61 5.4 Measurement Calibration and Validation ................................................................ 66 5.5 Summary .................................................................................................................. 74 VI. Compact, Low-Power, Low-VHF Mobile Radio Networking ....................... 76 6.1 Introduction ............................................................................................................. 76 6.2 Frequency Conversion Circuit Design and Analysis ............................................... 77 6.3 Antenna Miniaturization and Compact Mobile Radio System ................................ 81 6.3.1 Miniaturized Low-VHF Antennas .................................................................... 81 6.3.2 Radio System Fabrication and Integration ........................................................ 84 vi 6.4 Performance Characterization ................................................................................. 87 6.4.1 Measurement Setup and Scenarios ................................................................... 87 6.4.2 Measurement Results and Discussion ............................................................... 91 6.5 Summary .................................................................................................................. 94 VII. Conclusion and Future Work ........................................................................ 95 7.1 Conclusion ............................................................................................................... 95 7.2 Future Work ............................................................................................................. 97 7.2.1 Electrically