Title Page
Abstract
Contents
Chapter 1. Introduction 17
1.1. Study Background 17
1.2. Purpose of Research 19
1.3. Technical Characteristics applied in this Study 21
1.4. Research Trends 25
1.4.1. Thin Film Fiber Resonator 25
1.4.2. flexible antenna 27
Reference 29
Chapter 2. New Design Topology of High-Q Factor Printed base Antenna having Unequal Width and Pitch used for Near-field Wireless Power Transmission 33
2.1. Introduction 33
2.2. Modelling of Resonator Parasitic Components 37
2.2.1. Inductance 38
2.2.2. Resistance 39
2.2.3. Capacitance 40
2.3. Analysis of the Relationship between the Quality Factor and Each Variable that Determines the Form Factor 41
2.3.1. Relationship between Quality-factor and width & pitch 42
2.3.2. Relation ship between Quality-factor and diameter 45
2.3.3. Proposed Antenna 47
2.4. Wireless Power Transmission Test 51
2.4.1. Efficiency Test 51
2.4.2. Comparison with conventional coil antenna 53
2.5. Actual Cell Phone Charging Experiment 59
2.6. Chapter Summary 61
Reference 62
Chapter 3. E-textile based Wavy Surface WPT Flexible Antenna with Frequency Self-reconfiguration Function for Battery-less Sensor Platform 64
3.1. Introduction 64
3.2. Antenna Design using Gridded Substrate 66
3.2.1. Waveguide Design to Obtain Dielectric Constant of Gridded Substrate 67
3.2.2. Gridded Substrate Antenna Design 69
3.3. Wavy Surface Antenna 72
3.3.1. Wavy Structure Analysis - Parasitic Capacitance 72
3.3.2. Wavy Structure Analysis - Parasitic Inductance 77
3.3.3. Wavy Surface Antenna Design 77
3.3.4. Fabrication & Test of Wavy Surface Antenna 82
3.3.5. Application of Wavy Surface Antenna 85
3.3.6. Stability Test of Wavy Surface Antenna 87
3.4. Chapter Summary 88
Reference 90
Chapter 4. Q-Factor Improvement of Embroidered WPT Resonator with Low Resistive Structure for Driving Wearable Sensor Platform 93
4.1. Introduction 93
4.2. Printed 2D Resonator Modelling & Analysis 98
4.2.1. Inductance 100
4.2.2. Resistance 101
4.2.3. Relationship between Quality-factor and Width & Radius 102
4.3. Fabrication of Enhanced Fiber Resonators for Wireless Power Transmission 104
4.3.1. Properties of Conductive Yarns 104
4.3.2. Structural Improvement Method for Reducing Resonator Resistance 106
4.3.3. Electrical Properties of Double-sided Sewn Resonator with Conductive Cloth 107
4.4. Electrical Performance of Manufactured Resonator and Applied to Smart Clothing 109
4.4.1. Comparison with previous work 109
4.4.2. System demonstration on Smart Clothing 109
4.5. Chapter Summary 110
Reference 112
Publication List 114
Abstract in Korean 116
Table 1.1. Types of Energy Harvesting Technology and Electrical Characteristics. 19
Table 1.2. Types of wireless power transmission and its characteristics. 23
Table 2.1. Design constraints 37
Table 2.2. Figure 2.17 (a)~(f) Antenna Test Result (Actual Measurement) 53
Table 2.3. Figure 2.18 (a)~(d) Antenna Test Result (Actual Measurement) 55
Table 3.1. Comparison with Existing Papers 80
Table 4.1. Comparison of Conductive Yarn and Metal Yarn 94
Table 4.2. Design Constraints 96
Table 4.3. Conductive Yarn Investigation 104
Table 4.4. Comparison of Electrical Characteristics of Fabric Resonators 106
Table 4.5. Comparison with Existing Papers 109
Figure 1.1. Limits on sensor platform power consumption and battery capacity. 18
Figure 1.2. Types of wireless power transmission and its characteristics. 23
Figure 1.3. 2.4GHz wireless power transmission system. 25
Figure 1.4. 6.78MHz wireless power transmission system. 25
Figure 2.1. Top view of resonator for WPT. 33
Figure 2.2. Cross-sectional diagram of (a) circular coil antenna, (b) print based antenna. 34
Figure 2.3. (a) The original schematic for inductive coupled, (b) Parallel to series approximated Schematic. 35
Figure 2.4. Top view of 2-turns antenna for mutual inductance. 38
Figure 2.5. The parasitic component of printed base antenna according to (a) change of width and pitch. (b) Quality factor... 41
Figure 2.6. (a) Top view of conventional type resonator, (b) Comparison of result using commercial simulation tools and actual... 42
Figure 2.7. A model to explain Neumann's formula. 43
Figure 2.8. Coupling coefficient according to width and pitch length. 44
Figure 2.9. The parasitic component of printed base antenna according to (a) change of radius. (b) Quality factor simulated using... 46
Figure 2.10. (a) Top view of unequal antenna and (b) it's parasitic component. 46
Figure 2.11. H-field distribution of the printed base antenna. (6.78MHz, 1W) 47
Figure 2.12. Quality factor simulation result according to innermost radius and unequal factor. 48
Figure 2.13. Coupling coefficient according to power transmission distance. 49
Figure 2.14. Proposed unequal resonator design process. 50
Figure 2.15. (a) Test bed using Styrofoam to minimize external influence, (b) Equal printed based antenna, (c) Unequal printed base antenna. 51
Figure 2.16. Wireless power transmission efficiency to show the performance improvement of the proposed antenna. 52
Figure 2.17. (a) Coil antenna (turn number: 14, pitch: 4mm), (b) Coil antenna (turn number: 23, pitch: 1.5mm), (c) Coil antenna (turn... 53
Figure 2.18. (a) Printed antenna (turn number: 13, pitch: unequal), (b) Coil antenna (turn number: 8, pitch: 7.5mm), (c) Coil antenna... 54
Figure 2.19. (a) Experiment environment. A rectangular antenna (t1, t2, t2) was used as a transmission (Tx) antenna, and a circular... 55
Figure 2.20. Comparison of transmit efficiency according to z-axis change. 56
Figure 2.21. Comparison of transmit latent efficiency according to z-axis change. 56
Figure 2.22. Comparison of transmit efficiency according to x,y-axis change. 57
Figure 2.23. Cell phone charging experiment block diagram and distribution of losses. 59
Figure 2.24. (a) Cell phone charging testbed, (b) Receiving part. 59
Figure 2.25. (a) Power meter measurement result, (b) Oscilloscope measurement result. 60
Figure 2.26. Side view of field distribution (a) E-field, (b) H-field. 60
Figure 3.1. Side view of wavy surface antenna with gridded air-gap substrate. 66
Figure 3.2. Form factor of 2.4GHz wave guide for calculating permittivity. 66
Figure 3.3. Changes in s11 magnitude and phase angle according to the ratio of PDMS and air within the operating frequency range of waveguide. 67
Figure 3.4. Changes in permittivity and loss tangent according to PDMS and air ratio within the waveguide's operating frequency range. 68
Figure 3.5. Changes in permittivity and loss tangent according to PDMS and air ratio. 68
Figure 3.6. Comparison of conventional antenna and gridded antenna design results. monopole: (a) conventional antenna, (b) gridded... 71
Figure 3.7. Conceptual diagram for explaining the parasitic capacitance of the wavy surface antenna. 71
Figure 3.8. Equivalent circuit with wavy surface structure in terms of transmission line. 71
Figure 3.9. Mathematical modelling method of wavy surface structure. (a) Setting a variable to mathematicalize a single wavy surface. (b)... 73
Figure 3.10. Comparison of capacitance on a flat surface and on a wavy surface. 73
Figure 3.11. Wavy surface antenna design results. monopole: (a) wavy surface antenna, (b) S11 comparison result, patch: (c) wavy... 76
Figure 3.12. Center frequency shift and magnetic change according to the degree of antenna bending. 76
Figure 3.13. Conceptual diagram for explaining the parasitic inductance of the wavy surface antenna. 77
Figure 3.14. Equivalent circuit and Smith chart changes when a wavy structure is added. 78
Figure 3.15. Bended wavy surface antenna design results. monopole: (a) bended wavy surface antenna (40R), (b) S11 comparison result,... 78
Figure 3.16. Frequency reconfiguration circuit simulation (a) Antenna equivalent circuit and passive reconfiguration element, (b)... 79
Figure 3.17. Conventional patch antenna (a) production sequence, (b) configuration and Wavy surface antenna (c) production sequence, (b) configuration. 82
Figure 3.18. Fabrication result of monopole wavy surface antenna and patch wavy surface antenna. 83
Figure 3.19. Power transfer experiment of wavy surface antenna (a) block diagram, (b) experiment in flat, 60R, 30R, (c) result 84
Figure 3.20. System configuration for implementing a batteryless sensor platform. 85
Figure 3.21. (a) Wireless power transfer experiment of wavy surface antenna and batteryless sensor platform, (b) Result in flat (c) Result... 86
Figure 3.22. (a) Wireless power transfer experiment of wavy surface antenna and batteryless sensor platform, (b) Antenna bending test... 87
Figure 3.23. Center frequency repetition test according to bending degree of Wavy surface antenna 88
Figure 4.1. The most representative form among manufactured yarns (filament yarns & spun yarns). 94
Figure 4.2. Mock-up of smart clothing with resonator for wireless power transmission. 95
Figure 4.3. Top view(left) of resonator for WPT. Cross-sectional diagram(right) of (a) circular coil resonator, (b) print 2D resonator. 97
Figure 4.4. Equivalent circuit of Wireless power transfer (WPT) system. 98
Figure 4.5. Top view of 2-turns antenna for L_M calculation. 100
Figure 4.6. Q_factor change according to the radius and width of the resonator. 102
Figure 4.7. Print-based 2d resonator made of copper on fr_4 substrates. And a fiber resonator made in the same form factor. 103
Figure 4.8. An Enlarged view of the zigzag structure used in previous studies. 104
Figure 4.9. Manufacturing process of double-sided sewn resonator with conductive cloth. 105
Figure 4.10. Top view & side view of three types (single-sided, single-sided with cloth, double-sided with cloth) of embroidered... 105
Figure 4.11. (a) System configuration of wireless power transfer and (b) its fabricated draft on clothing. 108
Figure 4.12. Comparison in wireless power transfer efficiency between using a single-sided sewn resonator and using a double-... 108