Smart Base Station Antennas for MIMO and 5G Mobile Communications By Ahmed Alieldin Thesis submitted in accordance with the requirements for the award of the degree of Doctor of Philosophy of the University of Liverpool August 2019 P a g e | i To my dear wife, daughter, son and the soul of my parents. P a g e | ii Acknowledgements First, I thank GOD ALMIGHTY who has given me the mental and physical strength and confidence to do this work. This thesis would have not seen the light without the support and guidance of many people who are acknowledged here. I would like to express my deep gratitude to my supervisor, Professor Yi Huang for offering me this opportunity. His kind support, fruitful advice, critical discussions and vast experience have motivated me during the whole time of my studies. Special thanks to Mr. Mark Norman and Mr. Mark Burnley, who are technicians at electrical engineering workshop for their assistance in fabricating our designs. Thanks to Rogers Corporation for providing us with free samples of PCB boards. I would also like to thank Dr. Manoj Stanley at NPL, Dr. Jiafeng Zhou, Dr. Chaoyun Song, Dr. Stephen J. Boyes at DSTL, Dr. Qian Xu at Nanjing, Mr. Bahaa Al-Juboori and Mr. Sumin Joseph for their contributions and collaborations in editing the published papers of this research and for their friendly support. Special thanks to Dr Abed Poursohrab, Dr. Muaad Hussein and Dr. Ahmed Al-Tahmeesschi for their valuable advice and company during the PhD life. Thanks to all my friends and colleagues in the RF group for providing such a lovely and collaborative environment for research. Finally, thanks to my beloved wife, my daughter and my son for their invaluable support. This journey would not have been possible without their love and prayers. P a g e | iii Table of Contents Abstract ..................................................................................................................... vii List of Publications and Patents ............................................................................ viii Acronyms .................................................................................................................... x List of Figures .......................................................................................................... xiii List of Tables ........................................................................................................... xix Chapter 1. Introduction ............................................................................................. 1 1.1. Evolution of Mobile Communications .............................................................. 1 1.2. Evolution of the Base Station Antennas ............................................................ 3 1.2.1. Antenna Systems for 2G GSM .......................................................................... 5 1.2.2. Rolling out 3G UMTS ....................................................................................... 9 1.2.3. Moving to 4G LTE .......................................................................................... 10 1.3. Research Motivations ...................................................................................... 13 1.4. Organization of the Thesis ............................................................................... 14 Chapter 2. Base Station Antenna Parameters and Applications ......................... 16 2.1. Outdoor Base Station Antenna ........................................................................ 16 2.1.1. Azimuth Radiation Pattern .............................................................................. 16 2.1.2. Elevation Radiation Pattern ............................................................................. 18 2.1.3. Gain ................................................................................................................. 19 2.1.4. Diversity and Isolation .................................................................................... 20 2.1.5. Power Handling Capabilities ........................................................................... 21 2.2. Indoor Base Station Antennas.......................................................................... 22 2.3. Multiband Antenna Arrays ............................................................................... 23 2.3.1. Independent Antennas Mounted Side-by-Side under a Single Radome ......... 24 2.3.2. Interleaved Arrays ........................................................................................... 24 2.3.3. Wideband Arrays ............................................................................................ 25 2.4. 5G Base Station Antennas ............................................................................... 25 2.4.1. Analogue Static Multi-beam Antenna ............................................................. 26 2.4.2. Analogue Dynamic Multi-beam Antenna ....................................................... 27 2.4.3. Digital Dynamic Multi-Beam Antenna ........................................................... 28 2.5. Summary .......................................................................................................... 29 Chapter 3. MIMO Antenna Systems ...................................................................... 30 3.1. MIMO System ................................................................................................. 30 P a g e | iv 3.2. Antenna Diversity Techniques ......................................................................... 31 3.2.1. Spatial Diversity .............................................................................................. 32 3.2.2. Polarization Diversity ...................................................................................... 33 3.2.3. Pattern Diversity.............................................................................................. 34 3.3. MIMO Antennas and Key Parameters ............................................................. 35 3.3.1. Mutual Coupling ............................................................................................. 35 3.3.2. Envelope Correlation Coefficient (ECC) ........................................................ 36 3.3.3. Diversity Gain ................................................................................................. 36 3.4. MIMO Antenna for Base Stations ................................................................... 37 3.5. Summary .......................................................................................................... 39 Chapter 4. Reconfigurable Dual-Mode Antenna for Base Stations .................... 40 4.1. Introduction ..................................................................................................... 40 4.2. Dual-Polarized Antenna Element .................................................................... 42 4.2.1. Antenna Element Design ................................................................................. 42 4.2.2. Methodology and Principle of Operation ........................................................ 43 4.3. Three-Sector Antenna ...................................................................................... 45 4.3.1. Mode 1: Omnidirectional Radiation Mode ..................................................... 47 4.3.2. Mode 2: Sectoral Radiation Mode .................................................................. 53 4.4. Parametric Studies ........................................................................................... 55 4.4.1. Effect of the Elliptical Slotted Dipoles ........................................................... 55 4.4.2. Effect of the Triangular-Shaped Metallic Reflector ........................................ 56 4.5. Summary .......................................................................................................... 58 Chapter 5. Optimum Partitioning of a Phased –MIMO Antenna Array .......... 59 5.1. Introduction ..................................................................................................... 59 5.1.1. What is Phased-MIMO System? ..................................................................... 59 5.1.2. Partitioning of Phased-MIMO Antenna Array ................................................ 61 5.2. A New Formula for Optimum Partitioning of a Phased-MIMO Array............ 63 5.3. Summary .......................................................................................................... 70 Chapter 6. A Dual-Broadband MIMO Overlapped Antenna Subarrays ........... 71 6.1. Introduction ..................................................................................................... 72 6.2. Fylfot-Shaped Antenna Element ...................................................................... 73 6.2.1. Antenna Structure............................................................................................ 73 6.2.2. Methodology and Principles of Operation ...................................................... 75 6.2.3. Effect of Dipole Dimensions ........................................................................... 84 P a g e | v 6.2.4. Effect of the Small Metallic Reflector ............................................................ 87 6.3. MIMO Overlapped Antenna Subarrays ........................................................... 88 6.4. Summary .......................................................................................................... 99 Chapter 7. A Triple-Band Indoor