UNIVERSITAT POLITECNICA´ DE CATALUNYA PONTIFICIA UNIVERSIDAD CATOLICA´ DEL PERU´ CENTRE TECNOLOGIC´ DE TELECOMUNICACIONS DE CATALUNYA Efficient Rectenna Design for Ambient Microwave Energy Recycling by Gianfranco And´ıaVera A thesis submitted in partial fulfillment for the degree of Engineer in the Escola T´ecnicaSuperior d'Enginyeria de Telecomunicaci´ode Barcelona Departament de Teoria del Senyal i Comunicacions July 2009 \Por nuestra ignorancia no sabemos las cosas necesarias; por el error las sabemos mal." A.A.R.G. UNIVERSITAT POLITECNICA´ DE CATALUNYA PONTIFICIA UNIVERSIDAD CATOLICA´ DEL PERU´ CENTRE TECNOLOGIC´ DE TELECOMUNICACIONS DE CATALUNYA Abstract Escola T´ecnicaSuperior d'Enginyeria de Telecomunicaci´ode Barcelona Departament de Teoria del Senyal i Comunicacions degree of Engineer by Gianfranco And´ıaVera The work focuses on designing, measuring and testing an antenna and rectifier circuit (RECTENNA) optimized for incoming signals of low power density. The rectenna is used to harvest electric energy from the RF signals that have been radiated by com- munication and broadcasting systems at ISM band centred in 2.45 GHz., This work contains methods to simulate rectennas with Harmonic Balance and electromagnetic full-wave Momemtum by Agilent Advanced Design Software, used of LPKF Milling machine for antenna fabrication , Vector Network Analyzer, spectral analyzer, digital generator, multimeter, and anechoic chamber for antenna and rectifier measurements. The work is motivated by two types of applications: (1) powering of low-power sensor and (2) RF energy recycling being aware of the energy consumption and effect to the natural environment. The goal of this work is to determine the usefulness of low-power rectification. Agradecimientos A mi familia: a mis padres, por su incondicional apoyo, y a mis hermanos, por su experiencia e inquietud, ustedes son la raz´ony el motivo de intentar hacerlo todo bien. Gracias a los momentos que compartimos, los que, y tal vez sin valorarlos a su tiempo, hicieron, sin duda alguna, que todos estos a~nossean espl´endidos. Muchas gracias, son una fuente inagotable de satisfacci´on. A los amigos que gan´een el transcurso de la carrera: Claudia, Alfredo, Gustavo, Alan y Lisset por escucharme, compartir experiencias e inspirar confianza; a los que me acompa~narondesde antes: Jos´eLuis, Bera Luc´ıa, Hugo Alexander; sin duda, de to- dos ellos y de nuestros problemas fue de lo que m´asaprend´ı. De esta etapa Barcelona, una m´asde cambios, y creo que determinante para poder hacer esta valoraci´ondesde otra perspectiva, hay algunos nombres en especial que no quiero dejar de mencionar por su amistad, amabilidad y colaboracion. Al trabajo m´as importante de mi carrera le puse tantas ganas porque alguien tuvo mucha f´een m´ı,sus ganas de trabajar y sobre todo de ayudar, gracias a ´ella dificultad se hizo interesante y el trabajo result´oentretenido, no s´oloen lo acad´emico,sino tambi´enpor el buen ambiente creado, gracias Apostolos, mi director de proyecto. Este buen ambiente se debe tambi´ena las buenas personas que conoc´ıen el CTTC, a David, por tu ayuda y por los buenos momentos que compartimos, las conversaciones, risas e historias hicieron que todo sea sencillo, a Selva, por su gran ayuda; a Ana, por el material brindado; gracias por su enorme simpat´ıa Debo agradecer tambi´ena mi director ponente Josep M. Torrents, por su gran ama- bilidad. en general, personas como las que menciono favorecer´ıancualquier escenario y har´ıandel trabajo el mejor ambiente. Gr`acies! iii Contents Abstract ii Acknowledgements iii List of Figures vi List of Tables ix 1 Introduction 1 1.1 Overview . 3 2 State Of The Art 4 2.1 History: Previous Power Transfer Technologies . 4 2.2 Recent Technologies of Rectenna . 6 2.3 Wireless Powering for Low-Power Distributed Sensors . 7 2.4 Electromagnetic Environment and Efficiency . 9 2.5 Example Rectenna Designs . 10 2.5.1 Feasibility and potential application of power scavenging from en- vironmental RF signals . 11 2.5.2 Linearly-polarized medium-power rectenna array . 12 2.5.3 Dual-polarized low-power rectenna element . 15 2.5.4 Broadband rectenna arrays for low-power arbitrarily polarized in- cident radiation with high power dynamic range . 16 3 Rectenna Design 22 3.1 A brief Background Information . 22 3.1.1 Harmonic Balance Simulation . 22 3.1.2 Square Patch Microstrip Antenna . 23 3.1.3 Microstrip Antenna Analytical Models . 24 3.1.4 Microstrip Antenna Feeding Techniques . 25 3.1.4.1 Aperture-coupled Feeding . 25 3.1.5 Basic Operation of the Aperture Coupled Microstrip Antenna . 26 3.1.6 Variations on the Aperture Coupled Microstrip Antenna . 28 3.1.7 RF to DC Rectifier . 29 3.2 Antena Design . 30 iv Contents v 3.2.1 Simulation Setup and Design Process . 31 3.3 Rectifier Design . 56 3.3.1 The Choice of the Diode . 57 3.4 Integrated Rectenna Design . 58 4 Fabrication and Measurements 70 4.1 Fabrication . 70 4.2 Measurements . 73 4.3 Measurement Setup and Limitations . 73 4.4 Measurements of the Optimized Size Antenna . 79 4.4.1 S11 Parameters . 79 4.4.2 Measurements on the Anechoic Chamber . 79 4.5 Measurements of the Optimized Size and Polarization Bandwidth Antenna 83 4.5.1 S11 Parameters . 83 4.5.2 Measurements on the Anechoic Chamber . 84 4.6 Measurements of the One Branch Rectifier Circuit . 84 4.6.1 S11 Parameters for the Matched one Branch Rectifier . 89 4.6.2 RF-DC Conversion Efficiency . 89 4.7 Measurements of the Integrated Rectenna . 93 4.7.1 Efficiency versus Incident Power . 93 4.7.2 Polarization . 95 5 Energy Storage and Management for Low-Power Applications 98 6 Conclusion and Future Work 100 Bibliography 101 List of Figures 2.1 RF to DC conversion efficiencies of rectennas . 7 2.2 Rectenna and associated power management circuit . 8 2.3 Microwave power sources and their typical power density levels . 8 2.4 Measurement Result of Major Place in Tokyo . 13 2.5 Measurement Results around Tokyo Tower . 14 2.6 Measured DC voltage as a function of the DC resistive load for three array sizes . 14 2.7 Measured DC power as a function of polarization mismatch between the transmitter and rectenna array . 15 2.8 Block diagram of rectenna and sensor system . 15 2.9 Dual-polarized 2.4 GHz. patch rectenna . 16 2.10 Circuit for source-pull simulation setup . 17 2.11 Harmonic balance for broadband rectenna array . 18 2.12 Measured reflected, rectified, and re-radiated harmonic power as a func- tion of incident power density . 19 2.13 Rectena arrays with different polarizations . 19 3.1 Rectangular microstrip antenna configuration . 24 3.2 Geometry of the basic aperture coupled microstrip antenna . 26 3.3 Smith chart plot of the impedance locus versus frequency for an aperture coupled microstrip antenna . 27 3.4 Villard voltage double and cascaded Villard voltage doublers . 29 3.5 Layers setup for microstrip aperture coupled antenna in ADS . 32 3.6 Calculating dimensions of an antenna by Line Calc tool, in Agilent ADS . 33 3.7 2D views of the two single feed aperture-coupled square patch microstrip antennas designed in Agilent ADS . 36 3.8 3D views of the first two single feed aperture-coupled square patch mi- crostrip antennas designed in Agilent ADS . 37 3.9 2D and 3D views of the optimized design, dual feed aperture-coupled square patch microstrip antenna (Agilent ADS) . 38 3.10 Simulated return loss of the first two designed antennas measured at the input port (Agilent ADS) . 39 3.11 Simulated return loss in first port in the dual feed line optimized size and bandwidth antenna's design (Agilent ADS) . 40 3.12 Simulated return loss in second port in the dual feed line optimized size and bandwidth antenna's design (Agilent ADS) . 40 3.13 Simulated impedance locus of firsts two designsof the antennas (Agilent ADS) . 41 vi List of Figures vii 3.14 Simulated impedance locus of first port in the dual feed optimized size and polarization bandwidth antenna's design (Agilent ADS) . 42 3.15 Simulated impedance locus of the second port in the dual feed optimized size and polarization bandwidth antenna's design(Agilent ADS) . 43 3.16 Absolute fields E and H for the first antenna designed (Agilent ADS) . 44 3.17 Absolute fields E and H for the second antenna designed (Agilent ADS) . 45 3.18 Absolute fields E and H per port in the dual feed optimized size and bandwidth antenna's design (Agilent ADS) . 46 3.19 Simulated 2D radiation pattern, gain and directivity for both antennas designed (Agilent ADS) . 48 3.20 Simulated 2D radiation pattern, gain and directivity for the dual feed optimized size and bandwidth antenna designed (Agilent ADS) . 49 3.21 Simulated 3D radiation pattern of the largest antenna (Agilent ADS) . 50 3.22 Simulated 3D radiation pattern of the optimized size antenna (Agilent ADS) . 51 3.23 Simulated 3D radiation pattern of the dual feed optimized size and band- width antenna (Agilent ADS) . 52 3.24 Simulated polarization in magnitude and phase for the largest antenna (Agilent ADS) . 53 3.25 Simulated polarization in magnitude and phase for the optimized size antenna (Agilent ADS) . 54 3.26 Simulated polarization in magnitude and phase for the dual feed opti- mized size and bandwidth antenna (Agilent ADS) . 55 3.27 Efficiency of a diode vs. various parameters . 58 3.28 Comparison of the Schottky Diodes . 59 3.29 Basic topology of one branch rectifier circuit (Agilent ADS) . 59 3.30 Inserting the matching network with Smith Chart Matching tool (Agilent ADS) . 60 3.31 Working with Smith Chart Matching tool (Agilent ADS) .