WWW.ABSTRACT.XLIBX.INFO
FREE ELECTRONIC LIBRARY - Abstract, dissertation, book
 
<< HOME
CONTACTS



Pages:   || 2 | 3 | 4 | 5 |   ...   | 12 |

«by Sangjo Choi A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy (Electrical Engineering) in ...»

-- [ Page 1 ] --

Efficient Antennas

for Terahertz and Optical Frequencies

by

Sangjo Choi

A dissertation submitted in partial fulfillment

of the requirements for the degree of

Doctor of Philosophy

(Electrical Engineering)

in the University of Michigan

Doctoral Committee:

Professor Kamal Sarabandi, Chair

Professor Anthony Grbic

Professor Amir Mortazawi

Assistant Professor Thomas Schwarz

© Sangjo Choi 2014

All Rights Reserved

To God

To my father Siyoung Choi, and my mother Jaenam Jeon To my fiancé Saebom Jung ii

ACKNOWLEDGEMENTS

First and foremost, I would like to deeply thank and dedicate all my success to God, my parents, sister, and fiancé. Without their love and care, I would not be able to accomplish my ph.D work.

I want to express my sincere gratitude and appreciation to my advisors Prof.

Kamal Sarabandi for his continuous support, encouragement and guidance throughout my studies. I would like to extend my sincere gratitude to my other committee members, Prof.

Amir Mortazawi, Prof. Anthony Grbic and Prof. Thomas Schwarz for devoting their time to review this thesis and advising me with valuable suggestions.

I would like to thank my colleagues and friends at the Radiation Laboratory and EECS for constructive and insightful discussions. I thank Dr. Adib Nashashibi, Dr.

Leland Pierce, Dr. Juseop Lee, Dr. Jungsuek Oh, Dr. Young Jun Song, Dr. Victor Lee, Dr.

Adel Elsherbini, Dr. DaHan Liao, Dr. Fikadu Dagefu, Dr. Meysam Moallem, Gurkan Gok, Jihun Choi, Michael Benson, Jiangfeng Wu, Abdulkadir Yucel, Hamid Nejatie, Kyunghoon Lee, Kyusang Lee, Seungku Lee, Taehee Jang, and Hyeongseok Kim.

Finally, I would like to thank Pastor. Sun Myung Lyu and my friends at Korean Presbyterian Church of Ann Arbor.

Sangjo Winter, 2014, Ann Arbor.

iii

TABLE OF CONTENTS

DEDICATION

ACKNOWLEDGEMENTS

LIST OF FIGURES

Abstract

Chapter 1 Introduction

1.1 Background

1.2 Thesis Outline

Chapter 2 Efficient Dipole Antenna using a Nanomaterial, Bundled Carbon Nanotubes

2.1 Introduction

2.2 Carbon Nanotubes

2.3 Resistive Sheet Model of Bundled Carbon Nanotube

2.4 Resistivity of Bundled Carbon Nanotubes

2.5 Method of Moment (MoM) Formulation

2.6 Conductivity of Thin Gold Film

2.6.1 Drude-Smith Model

2.6.2 Surface Resistivity of Thin Gold Film

2.7 Antenna Simulation

2.7.1 Strip Antenna

2.7.2 Radiation Efficiency

2.8 Conclusion

Chapter 3 Gold Bowtie Antenna Topology for High-Efficiency Thermophotovoltaics

3.1 Thermophotovoltaics

3.2 Bowtie Nanoantenna Design

3.2.1 Maximum Power Transfer

3.2.2 Open-ended Transmission Line Stub

3.2.3 Field Enhancement at the terminals of the bowtie antenna

3.2.4 Absorption Efficiency

iv 3.2.5 Radiation Efficiency

3.3 Array Design

3.4 Conclusion

Chapter 4 Gold Bowtie Antenna Topology

4.1 Introduction

4.2 Bowtie Antenna Integrated with InGaAsSb Block

4.3 Sensitivity Comparison between Antenna-Loaded and Conven-tional IR Detectors

4.3.1 Johnson noise-limited case

4.3.2 Photon noise-limited case

4.4 Focal Plane Array Design

4.5 Conclusion

Chapter 5 Cross Dipole Antenna Topology for an IR Polarimetric Detector....... 76

5.1 Cross Dipole Antenna Topology and its usage for Direction Finding in the GHz range

5.1.1 Introduction

5.1.2 Cross Dipole Antenna Structure

5.1.3 Antenna Measurement

5.2 Antenna-Loaded IR Polarimetry System

5.2.1 Introduction

5.2.2 IR Cross Dipole Antenna Structure

5.3 Conclusion

Chapter 6 Conclusions and Future Work

6.1 Summary of Achievements

6.2 Future work

6.3 List of Publications

BIBLIOGRAPHY

v LIST OF FIGURES

Figure 1.1: (a) 160 nm-length gold dipole antenna with diameter of 10 nm and the gap size of 3 nm filled by vacuum, (b) and (c) field magnitude (complex electric field) along a cut plane across the center of the antenna of the antenna consists of PEC (at f = 1,150 THz) and Drude model gold (at f = 278 THz).

Figure 1.2: Dissertation Overview.

Figure 2.1: Densely aligned carbon nanotubes using repetitive CVD growths [55].

....... 19 Figure 2.2: Geometry of a strip antenna made up of bundled Carbon Nanotubes............ 21 Figure 2.3: Relative permittivity and conductivity (real) of thin gold film as a function of frequency

Figure 2.4: Strip dipole antenna geometry fed at center using a thin voltage gap.

........... 28 Figure 2.5: Input impedance of 150 µm strip antenna with BCNT density of (a) N:10 [CNTs/µm], (b) N:50 [CNTs/µm].

Figure 2.6: Reflection coefficient of 150 µm strip antenna with different BCNT densities [CNTs/µm].

Figure 2.7: Normalized antenna length (2L/λ) versus resonant frequencies.





Figure 2.8: Normalized antenna length (2L/λ) versus density of BCNT.

Figure 2.9: Radiation resistance of BCNT (N is higher than 5∙103[CNTs/µm]) and thin gold film at its resonant frequencies.

–  –  –

Figure 2.11: A magnified plot of antenna efficiencies for BCNT densities of 104 to 5∙104 [CNTs/µm] and a comparison to efficiencies of thin gold antenna.

Figure 2.12: Radiation efficiency (including impedance mismatch power loss to a 50 Ω transmission line) of strip dipole antenna of BCNTs (N: CNTs/µm) and thin gold film BCNT densities of 102 to 5∙104 [CNTs/µm].

Figure 2.13: A magnified plot of BCNT densities of 104 to 5∙104 [CNTs/µm] and a comparison to efficiencies of thin gold antenna.

Figure 3.1: Thermophotovoltaic structure.

Figure 3.2: Dielectric constant and conductivity of InGaAsSb.

Figure 3.3: Bowtie antenna structure in one plane.

Figure 3.4: Input impedance of bowtie antenna loaded with an air gap(dashed line) and bowtie antenna intrinsic input impedance(solid line) with L = 605 nm, W = 160 nm, α = 30°, H = 30 nm, and l = 30 nm.

Figure 3.5: Equivalent circuit of the bowtie antenna loaded with InGaAsSb load in receiving mode.

Figure 3.6: Input impedance of the bowtie antenna loaded with the InGaAsSb load (solid line with dots), and input impedance of the bowtie antenna loaded with the InGaAsSb load and a shunt ideal inductor having inductance of 0.

12 pH (dashed line), and bowtie antenna intrinsic input impedance (solid line).

Figure 3.7: Open-ended transmission line connected in shunt with the InGaAsSb load.

.. 52 Figure 3.8: Magnitude of complex electric field on a plane between the two strips of the transmission line for a plane wave illumination at 180 THz.

–  –  –

Figure 3.10: Unit cell (950 nm × 610 nm) of the bowtie antenna for infinite array.

........ 55 Figure 3.11: Absorption efficiency of InGaAsSb slab as a function of the slab thicknesses from 500 nm to 4000 nm.

Figure 3.12: Absorption efficiency of bowtie antenna loaded InGaAsSb block (30 nm × 30 nm × 30 nm) with and without a back metallic reflector.

Figure 3.13: The series and its parallel array configuration of the bowtie antennas and the field distribution calculated from the tangential H field on the gold surfaces.

................. 60 Figure 4.1: Unit cell (950 nm × 610 nm) of the bowtie antenna for infinite array of IR detector.

Figure 4.2: Optical area and detector area for a bulk InGaAsSb detector and an antenna loaded IR detector.

Figure 4.3: 45°-titled array configuration of bowtie antennas illuminated with a vertical and 45°-titled polarizations and the resulting current distributions (calculated from the tangential H field on the gold surface).

Figure 5.1: CP cross dipole antenna.

Figure 5.2: Polarization map of CP cross dipole antenna.

Figure 5.3: Illustration of polarization status at (a) the y-z plane and (b) the x-z plane (red-colored and blue-colored shapes indicate LHCP and RHCP respectively).

............. 83 Figure 5.4: A comparison between radiation pattern (gain) for the cross dipole antenna and a half-wave dipole antenna at (a) x-y plane as a function of phi (ϕ) and (b) x-z plane as a function of theta (θ).

Figure 5.5: (a) The CP cross dipole antenna using a balun structure in simulation and (b) the fabricated antenna.

viii Figure 5.6: The CP cross dipole antenna structure using the balun structure in simulation.

Figure 5.7: S11 of the CP cross dipole antenna using the balun structure in simulation and fabricated antenna.

Figure 5.8: Axial ratio of the CP cross dipole antenna using the balun structure in simulation and fabricated antenna.

Figure 5.9: Radiation pattern (normalized gain) of the antenna of in measurement and simulation of (a) x-y plane as a function of phi(ϕ) and (b) x-z plane as a function of theta (θ) at 2.

58 GHz.

Figure 5.10: Tapered-bowtie antenna geometry for vertical polarization.

Figure 5.11: Input impedance (Rin + jXin) of the tapered-bowtie antenna loaded with vacuum and the intrinsic input impedance (Rbowtie + jXbowtie) of the antenna (vacuum is de-embedded).

Figure 5.12: CP cross tapered bowtie antenna structure and its dimensions.

Figure 5.13: The magnitude ratio and the normalized phase difference between radiated electric field in ϕ and θ direction in the antenna's boresight.

Figure 5.14: Input impedance (Rin + jXin) of the cross bowtie antenna loaded with vacuum and the intrinsic input impedance (Rbowtie + jXbowtie) of the antenna (vacuum is de-embedded).

Figure 5.15: CP cross tapered bowtie antenna structure connected with open-ended transmission lines and its dimensions.

Figure 5.16: The magnitude ratio and the normalized phase difference between radiated electric field in ϕ and θ direction in the antenna's boresight.

Figure 5.17: The field enhancement at the gap of the cross tapered-bowtie antenna.

...... 98

–  –  –

1.1 Background The crowded wireless communication bands in the gigahertz (GHz) frequency range and the ever-increasing demand for more bandwidth has motivated the exploitation of the unexplored spectrum of electromagnetic waves such as the terahertz (THz) band.

The higher bandwidth of the THz band has a potential to achieve an extremely high data rate, such as 1 terabit-per-second, for future wireless devices [1]. The THz band corresponds to the segment of the electromagnetic spectrum from 0.3 THz to 3 THz (corresponding to wavelengths in the range of 0.1 mm ~ 1 mm) in between the millimeter and far-infra (IR) waves [2]. Due to the lack of THz sources and detectors, the THz band has not been thoroughly explored for communications [3]. Until now, low bandwidth upand down-converters as well as low gain amplifiers in the lower part of the THz band have limited the output power level and bandwidth of THz communication systems. THz sources are also hard to find. Current technology relies on mixing optical sources such as lasers to generate low to moderate power levels. Such sources suffer from large power consumption and are very bulky. Current receivers at THz frequencies rely on direct detection, using Schottky diodes, bolometers, thermopiles, pyroelectrics, etc, which is not band selective and has a low dynamic range and sensitivity [4]. As mentioned earlier, THz radiation is absorbed by most materials, including the molecules in the atmosphere such as water vapor. For such systems, line of sight propagation is needed and even for such conditions, the range is rather limited due to the inherently high path loss. Since path-loss is relatively high and receivers are not sensitive, much effort has been placed on maximizing the available incident power to the detector. This is where nanoantennas can play a significant role.



Pages:   || 2 | 3 | 4 | 5 |   ...   | 12 |


Similar works:

«ISSN 2219-6048 Историческая и социально-образовательная мысль. 2014. № 1 (23) УДК 316 Афаунов Анзор Зурабович, Afaunov Anzor Zurabovich, адъюнкт кафедры философии и социологии КрасноGraduate, Chair of Philosophy and Sociology, Krasnodar дарского университета МВД России University under the Ministry of Internal Affairs of Russia akademus07@rambler.ru...»

«ABSTRACT Title of Dissertation: ULTRA-SMALL SCALE MECHANICAL PROPERTIES MEASUREMENT Michael Scott Gaither, Doctor of Philosophy, 2011 Dissertation Directed by: Isabel K. Lloyd Associate Professor Department of Materials Science and Engineering Robert F. Cook Group Leader, Nanomechanical Properties National Institute of Standards and Technology Adjunct Professor Department of Materials Science and Engineering In order for the microelectromechanical systems (MEMS) industry to continue to grow and...»

«Gregory Phipps Figures in American Literary Pragmatism: Henry James and the Metaphysical Club Gregory Phipps Department of English McGill University, Montreal August, 2010 A Thesis Submitted to McGill University in Partial Fulfilment of the Requirements of the Degree of Doctor of Philosophy © Gregory Phipps 2010 Gregory Phipps Table of Contents Introduction Chapter I: Charles Peirce, The Wings of the Dove, “The Beast in the Jungle” Section 1: “Inroads of Ideas from Without”: Charles...»

«Labor Unions in Japan Philosophy, Structure, Activities Nomura, Masami 1 Summary The overwhelming majority of labor unions in Japan are enterprise unions. There have been two contrasting views on the Japanese enterprise unions. Some praises them as the most advanced organization of workers' representatives. They share information with the management and make efforts to present important interests of employees. As skill of employees is enterprise-specific, labor turnover is disadvantageous to...»

«EXPLORATORY LEARNING FOR WIRELESS NETWORKING Thomas Sturgeon A Thesis Submitted for the Degree of PhD at the University of St Andrews Full metadata for this item is available in Research@StAndrews:FullText at: http://research-repository.st-andrews.ac.uk/ Please use this identifier to cite or link to this item: http://hdl.handle.net/10023/1702 This item is protected by original copyright This item is licensed under a Creative Commons Licence Exploratory Learning for Wireless Networking Thomas...»

«UNIVERSITY OF CALGARY The Prairie Flower: A Biography of the Russian-Ukrainian Church of Evangelical Christians in Benito, Manitoba from 1928 to 1996 by Sergey Valeryevich Petrov A THESIS SUBMITTED TO THE FACULTY OF THE GRADUATE STUDIES IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY DEPARTMENT OF RELIGIOUS STUDIES CALGARY, ALBERTA SEPTEMBER, 2010 © Sergey Petrov 2010 ABSTRACT The Russian-Ukrainian community of Evangelical Christians existed in the village of...»

«La voie ASP-C5L2 : un pont entre l’homéostasie métabolique et l’inflammation Thèse Alexandre Fisette Doctorat en physiologie-endocrinologie Philosophiæ doctor (Ph.D.) Québec, Canada © Alexandre Fisette, 2013 Résumé Les récents développements de la recherche ont permis de caractériser le tissu adipeux en tant qu’organe endocrine majeur et à associer l’obésité à un phénotype d’inflammation chronique, surnommé métaflammation. Cette thèse de doctorat s’attarde...»

«Mary Corwin Herring, Ph.D. Department of Curriculum and Instruction Division University of Northern Iowa 159a Schindler Education Center Cedar Falls, IA 50614-0606 Phone: (319) 273-2368 E-mail: mary.herring@uni.edu EDUCATION Doctor of Philosophy, Curriculum and Instruction: Instructional Technology Iowa State University, Ames, Iowa 1997 Master of Science, Education: Physical Education North Dakota State University, Fargo, ND 1989 Bachelor of Science, Physical Education North Dakota State...»

«Regulating Word Order in Modern Greek: Verb Initial and non-Verb Initial orders & the Conceptual-Intentional Interface Thesis submitted to University College London in partial fulfilment of the requirements for the degree of Doctor of Philosophy Axiotis Kechagias Research Department of Linguistics University College London I, Axiotis Kechagias, confirm that the work presented in this thesis is my own. Where information has been derived from other sources, I confirm that this has been indicated...»

«“Can’t Go Home Again: Sovereign Entanglements and the Black Radical Tradition in the Twentieth Century” by Alvaro Andrés Reyes Literature Program Duke University Date:_Approved: _ Wahneema Lubiano, Supervisor _ Michael Hardt, Supervisor _ Kathi Weeks _ Fred Moten Dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Literature Program in the Graduate School of Duke University ABSTRACT “Can’t Go Home Again: Sovereign...»

«RESERVOIR QUALITY AND LATERAL VARIABILITY OF BIOTURBATED SHALLOW MARI NE SUCCESSIONS By © Nicola S. Tonkin A thesis submitted to the Schoo l of Graduate Studies in partial fulfillm ent of the requir ements for the degree of Doctor of Philosophy Department of Earth Sc iences Memorial Univers ity of Newfoundland Abstract In bioturbated reservoir facies, ichnolog is integral toreservoircharac terization. y Ichnological analysis ofa reservoir facies and subsequent c1assification into ichnofabrics...»

«THE OPERATING AND FINANCIAL PERFORMANCE OF NEWLY PRIVATIZED STATEOWNED ENTERPRISES IN MALAYSIA ISNURHADI BANALUDDIN UNIVERSITI SAINS MALAYSIA THE OPERATING AND FINANCIAL PERFORMANCE OF NEWLY PRIVATIZED STATE-OWNED ENTERPRISES IN MALAYSIA By ISNURHADI BANALUDDIN Thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy June 2007 THE OPERATING AND FINANCIAL PERFORMANCE OF NEWLY PRIVATIZED STATE-OWNED ENTERPRISES IN MALAYSIA By ISNURHADI BANALUDDIN THE THESIS...»





 
<<  HOME   |    CONTACTS
2016 www.abstract.xlibx.info - Free e-library - Abstract, dissertation, book

Materials of this site are available for review, all rights belong to their respective owners.
If you do not agree with the fact that your material is placed on this site, please, email us, we will within 1-2 business days delete him.