A PLANAR AND INTEGRATED RECTENNA FOR WIRELESS POWER RECEPTION by VINAY RAMACHANDRA GOWDA Presented to the Faculty of the Graduate School of The University of Texas at Arlington in Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCE IN ELECTRICAL ENGINEERING THE UNIVERSITY OF TEXAS AT ARLINGTON May 2011 Copyright © by VINAY RAMACHANDRA GOWDA 2011 All Rights Reserved ACKNOWLEDGEMENTS I would like to offer special thanks to my advisor Dr. Mingyu Lu for his continuous help, guidance and support throughout my thesis. His patience, experience, and knowledge have been invaluable throughout my research and I am truly grateful for this. I would like to thank him for giving me a opportunity to work in the Wave Scattering Research Centre which I truly loved working in. I would like to express my gratitude to Dr. Jonathan Bredow and Dr. Saibun Tjuatja for their encouragement and for reading the thesis. I would also like to thank Dr. W. Alan Davis and Dr. William E. Dillon, my graduate advisors for their advice and guidance throughout my Master of Science (M.S) degree. Also, I received academic guidance from Shaoshu Sha, Suman Kumar Gunnala and Vinay Vikram Magadi for which I will be truly obliged. I would also like to thank Dr. Huiqing Zhai for his help in HFSS simulaitions. I am indebted to my family, my Mother Radha C, my Father Ramachandra Gowda and my adorable sister Bindu Ramachandra for their unwavering love and support throughout my entire life. April 15, 2011 iii ABSTRACT A PLANAR AND INTEGRATED RECTENNA FOR WIRELESS POWER RECEPTION Vinay Ramachandra Gowda (M.S) The University of Texas at Arlington, 2011 Supervising Professor: Mingyu Lu In this thesis, a rectenna ("rectifier + antenna") for wireless power reception is designed and experimentally verified. The rectenna consists of two major components: one is a microstrip patch antenna and the other is a half-wave rectifier circuit. The microstrip antenna collects wireless power, and then, the received radio-frequency power is rectified to DC by the rectifier. The microstrip antenna and the rectifier circuit are simulated, fabricated, and tested separately. Before they are integrated, matching network is designed in between them to match the first harmonic. A few integrated rectenna’s are built around 2.4 GHz ISM band. The rectenna’s are entirely built over printed circuit boards, hence are planar and compact. Measurement results demonstrate 65% of power efficiency for the rectenna’s. iv TABLE OF CONTENTS ACKNOWLEDGEMENTS ................................................................................................................iii ABSTRACT ..................................................................................................................................... iv LIST OF ILLUSTRATIONS............................................................................................................. viii LIST OF TABLES ............................................................................................................................ xi Chapter Page 1. INTRODUCTION……………………………………..………..….. ..................................... 1 1.1 History of Wireless Power ................................................................................ 1 1.2 Application of Wireless Power .......................................................................... 2 1.3 Overview of Thesis ........................................................................................... 4 2. FUNDAMENTALS OF ANTENNNA ............................................................................... 6 2.1 Definition of an Antenna ................................................................................... 6 2.2 Antenna Parameters ........................................................................................ 6 2.2.1 Directivity .......................................................................................... 6 2.2.2 Gain .................................................................................................. 7 2.2.3 Input Impedance .............................................................................. 8 2.2.4 Antenna Efficiency ........................................................................... 8 2.2.5 Beamwidth ..................................................................................... 10 2.3 Frii’s Transmission Equation .......................................................................... 10 2.4 Microstrip ........................................................................................................ 11 2.4.1 Introduction ................................................................................... 11 v 2.4.2 Microstrip Patch Antenna ............................................................... 12 2.5 Feeding Methods ........................................................................................... 14 2.5.1 Microstrip Line Feed ....................................................................... 14 2.5.2 Coaxial Feed .................................................................................. 15 2.5.3 Aperture-Coupled Feed ................................................................. 16 2.5.4 Proximity-Coupled Feed ................................................................ 17 2.6 Rectangular Patch .......................................................................................... 18 2.6.1 Transmission Line Model ............................................................... 19 2.6.2 Cavity Model .................................................................................. 20 2.7 Design Procedure .......................................................................................... 21 2.7.1 Specification of the Design ............................................................ 21 2.7.2 Parameters of the Patch Antenna .................................................. 22 2.8 Fabrication Procedure for the Antenna .......................................................... 23 2.9 Results .......................................................................................................... 25 2.9.1 Verification of the Frii’s Transmission Equation ............................. 29 3. INTEGRATED RECTENNA ......................................................................................... 30 3.1 Rectifier .......................................................................................................... 30 3.1.1 Simulation ...................................................................................... 30 3.1.2 Input Impedance ............................................................................ 33 3.2 Integrated Rectenna ....................................................................................... 37 3.2.1 Impedance Matching ...................................................................... 38 3.2.2 Calculations for the Integrated Antenna......................................... 42 3.2.3 Efficiency of the Rectenna ............................................................. 45 4. CONCLUSION AND FUTURE WORK .......................................................................... 46 vi REFERENCES ............................................................................................................................... 47 BIOGRAPHICAL INFORMATION .................................................................................................. 51 vii LIST OF ILLUSTRATIONS Figure Page 1.1 Wireless Toothbrush .................................................................................................................. 3 1.2 Splashpower mat ........................................................................................................................ 3 1.3 Christmas tree lit without wires .................................................................................................. 4 1.4 Block Diagram of Wireless Power Transmission System ......................................................... 5 2.1 Thevenin Equivalent of an Antenna .......................................................................................... 8 2.2 Antenna reference terminals ..................................................................................................... 9 2.3 Reflection, conduction and dielectric losses ............................................................................. 9 2.4 Two dimensional representation of Beamwidth ...................................................................... 10 2.5 Microstrip Layer Structure ....................................................................................................... 12 2.6 Representative shapes of Microstrip patch elements ............................................................. 13 2.7 Microstrip Feed for Patch Antenna .......................................................................................... 15 2.8 Coaxial Feed ........................................................................................................................... 16 2.9 Aperture-Couple Feed ............................................................................................................. 17 2.10 Proximity-Coupled Feed ........................................................................................................ 18 2.11 Top View of Patch Antenna ................................................................................................... 19 2.12 Side/Horizontal view of Patch Antenna ................................................................................