by Terry Kin-chung Lo. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1994. / Includes bibliographical references (leaf 128). / Dedication --- p.i / Acknowledgements --- p.ii / Chapter Chapter 1 --- Introduction / Chapter 1.1 --- Outline of Thesis --- p.1 / Chapter 1.2 --- Microstrip to Slotline Transition --- p.3 / Chapter 1.3 --- Finite Difference as a Numerical Method --- p.4 / Chapter Chapter 2 --- The Method of Finite Difference in Time Domain / Chapter 2.1 --- An Introduction and Brief History --- p.1 / Chapter 2.2 --- The Methodology of FDTD --- p.11 / Chapter 2.3 --- The Yee's Algorithm --- p.13 / Chapter 2.4 --- Stability Criterion --- p.19 / Chapter 2.5 --- Interfaces Between Media --- p.21 / Chapter 2.6 --- Lattice Truncation Condition --- p.24 / Chapter 2.7 --- Error Analysis --- p.28 / Chapter 2.8 --- Implementation of Programs --- p.33 / Chapter 2.9 --- Summary --- p.35 / Chapter Chapter 3 --- Absorbing Boundary Conditions / Chapter 3.1 --- Introduction --- p.39 / Chapter 3.2 --- Mur's ABC --- p.40 / Chapter 3.3 --- Liao's ABC --- p.42 / Chapter 3.4 --- Dispersive ABC --- p.45 / Chapter 3.5 --- Comparison between Mur's ABC & Liao's ABC --- p.47 / Chapter 3.6 --- "Comparison among Mur's 1st Order ABC, Liao's ABC & DBC" --- p.51 / Chapter 3.7 --- Summary --- p.55 / Chapter Chapter 4 --- Microstrip-Slotline Transitions / Chapter 4.1 --- Introduction --- p.57 / Chapter 4.2 --- Approach --- p.59 / Chapter 4.3 --- Single Quarter-Wave Microstrip-Slotline Transitions --- p.67 / Chapter 4.4 --- Single Y-Strip-Slotline Transitions --- p.78 / Chapter 4.5 --- Shorted-Stub Y-Strip-Slotline Transitions --- p.88 / Chapter 4.6 --- Y-Strip-180°-Slotline Transitions --- p.96 / Chapter 4.7 --- Y-Strip-Y-Slot Transitions --- p.104 / Chapter 4.8 --- Y-Strip-Open-Stub-Y-Slot Transitions --- p.112 / Chapter 4.9 --- YY-Transitions --- p.120 / Chapter 4.10 --- Summary --- p.127 / Chapter Chapter 5 --- Conclusions & Future Development / Chapter 5.1 --- Conclusions --- p.129 / Chapter 5.2 --- Future Development --- p.131 / Appendix / Fortran 77 Code of Single Quarter-Wave Microstrip-Slotline Transition --- p.132

In the analysis of optically controlled microstrip interdigitated gaps, an equivalent circuit model for simple interdigitated gap is obtained. As far as we know, this is the first report of optically controlled microstrip interdigitated gap equivalent circuit model. The amplitude and phase changes of interdigitated gaps under different illumination powers are calculated with this equivalent circuit model, which basically agree with the experimental results. Meanwhile, the effect on the transmission characteristics from the gap dimensions is also discussed. Finally a novel gap structure is described for optically controlled phase shifter application, whose transmission characteristics have nearly zero amplitude change and no less than 27 degrees phase change under different illumination powers when the transmission signal frequency is about 1.8 to 2.5GHz. Some detailed experimental results of this gap are presented in Chapter 5. / In this dissertation, a systematic work has been done to analyze the transmission characteristics and applications of optically controlled microstrip single gap and interdigitated gap devices on high resistivity silicon (HRS) wafer. Detailed simulations, experiments and the relative equivalent circuit models for these gap structures are presented. / Microwave photonics is a multi-disciplinary area that studies the interactions between microwave signals and optical signals. As one of the key elements, direct optical control of microwave semiconductor devices has been an area of growing interest since 1980's. They can be widely used in picosecond photoconductive switch, phase shifter, attenuator, high-speed sampling, gain control of amplifier and so on. / Some future work is also suggested based on the study in this dissertation. / Specifically, optically controlled microstrip discontinuities devices fabricated on semiconductor substrates have wide-ranging applications due to their simple fabrication, easy integration with other passive and active microwave devices. / When illuminated on the surface of the microstrip single gaps, the S 12 amplitude of this gap increases linearly as the optical illumination increasing, which is a good potential application for digital controllable attenuator. The change of the S12 amplitude is mainly due to the imaginary permittivity change of the HRS substrates. The equivalent circuit model is established to explain the amplitude and phase changed. The equivalent resistors have been calculated according to the excess carrier concentration profile after illumination, which match well with the experimental results. / Li Huiping. / "March 2005." / Adviser: K. T. Chan. / Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6619. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

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The advent of low-cost RFIC's fabricated in Silicon-based technologies has led to the use of monolithic lumped elements which are located on-die. While it is clearly advantageous to have a high degree of integration and thus fewer off chip elements, parasitic losses due to semiconducting substrate effects can be a performance-limiting factor. Microstrip spiral inductors are key components in many high frequency circuit designs, including MMIC's, RFIC's, and mixed-signal modules. However, the losses associated with spirals fabricated in a lossy substrate environment, such as in CMOS and bipolar technologies, are not accurately modeled by the current conventional techniques. This thesis presents a complete modeling technique for spiral inductors over such 'high-loss' substrates. The quasi-static solution for single and coupled Metal-Insulator-Substrate (MIS) microstrip structures has led to the development of methods for calculating the self and mutual line parameters r, l, g, and c, which are in turn utilized in the model for the microstrip spiral inductors in the same environment. The equivalent circuit model for the spiral inductors is based on the conventional low-loss spiral models with the inclusion of frequency-dependent losses due to semiconducting substrates. The distributed model for spirals in CMOS-based RFICs incorporates inductance calculations by the Partial Element Equivalent Circuit (PEEC) method, augmented by inductance and resistance calculations for the so-called skin effect mode by the spectral domain technique. In addition, the capacitances and shunt conductances can be computed by a Poisson solver for layered lossy media; both network analog and spectral domain methods are also used to find the shunt admittance per unit length for the microstrip structure as a fundamental element of the spiral. Simulations for typical structures have been performed to validate the modeling techniques via comparison with a commercial simulator and network analyzer measurements for a 9.5 turn spiral in CMOS for RFIC applications. / Graduation date: 1999

The reflectarray has been considered as a suitable candidate to replace the conventional parabolic reflectors because of its high-gain, low profile, and beam reconfiguration capability. Beam scanning capability and multi-band operation of the microstrip reflectarray have been main research topics in the reflectarray design. Narrow bandwidth of the reflectarray is the main obstacle for the various uses of the reflectarray. The wideband antenna element with a large phase variation range and a linear phase response is one of the solutions to increase the narrow bandwidth of the reflectarray. A four beam scanning reflectarray has been developed. It is the offset-fed microstrip reflectarray that has been developed to emulate a cylindrical reflector. Unlike other microstrip reflectarrays which integrates phase tuning devices such as RF MEMS switches and another phase shifters to the reflectarray elements and control the reflected phase, the beam scanning capability of the reflectarray is implemented by a phased array feed antenna. This method can reduce the complexity of the design of the beam switching reflectarray. A simple method has been investigated to develop multi-band elements in this dissertation. In approach to increase the coverage of the operation bands, a six-band reflectarray has been developed with two layers. Each layer covers three frequency bands. A Butler matrix is one of the useful beamforming networks for a phased array antenna. A Double-Sided Parallel-Strip Line (DSPSL) is adapted for the feeding network of eight array elements. The DSPSL operate very well to feed the microstrip antenna array over the bandwidth to reduce the sidelobe level and a high gain. In another topic of a Butler matrix, a dual-band Butler matrix has been proposed for multi-band applications. A modified Butler matrix is used to reduce a size and a sidelobe level. The bandwidth of the microstrip antenna is inherently small. A broadband circularly polarized microstrip antenna with dual-offset feedlines is introduced in this dissertation. Aperture-coupled feed method is used to feed the stacked patch antennas and a slotcoupled directional coupler is used for the circularly polarized operation. The research presented in this dissertation suggests useful techniques for a beam scanning microstrip reflectarray, phased array antenna, and wideband antenna designs in the modern wireless communication systems.

The purpose of this study is to analyze how and why Kelly initially began interjecting political satire into his comic strip Pogo and how he was able to avoid being blacklisted during the time of the Red Scare. The scope of this study includes a history of the medium, a biography of the author, and a discussion of humor as a means of dissent and personal artistry. The methodology uses both historical documentation and semiotic analysis of Kelly’s work from high school, the Disney studios, The New York Star and Pogo. Case studies include gender racial, and political analysis. The findings resulted from an analysis of the archive. Conclusions reached were that Kelly’s work created a new form of political dissent that was less satirical than editorial cartoons of the day and more directed toward the enjoyment of the reader rather than at any political affiliation, a form of comedic writing that continues to be used today in such forms as the Daily Show, Colbert Report and Saturday Night Live. This new form of political satire is important to journalistic studies since it reveals a theme of parrhesia, a Socratic term for speaking truth to power, that was further developed in the twentieth century by Star columnist I. F. Stone and French philosopher Michel Foucault. The primary limitation of this study was that Pogo was an extremely personal work, one that could not be duplicated by others successfully after the author died.

This work describes the design and measurement of a compact bidirectional ultrawideband (UWB) modified equiangular spiral antenna with an integrated feed internally matched to a 50-Ohm microstrip transmission line. A UWB transition from microstrip to double-sided parallel-strip line (DSPSL) soldered to a short (1.14 mm) twin-line transmission line feeds the spiral. The currents on the feed travel in a direction approximately perpendicular to the direction of the currents on the spiral at the points where the feed passes the spiral in close proximity (0.57 mm). Holes were etched from the metal arms of the spiral to reduce the impedance mismatch caused by coupling between the transmission line feed and the spiral. This work also describes a low-loss back-to-back transition from coaxial line to DSPSL, an in-phase connectorized 3 dB DSPSL power divider made using three of those transitions, a 2:1 in-phase DSPSL power divider, a 3:1 in-phase DSPSL power divider, a radial dipole fed by DSPSL, an array of those dipoles utilizing the various power dividers, and a UWB circular monopole antenna fed by DSPSL. Measured and simulated results show good agreement for the designed antennas and circuits.

Recently, the accuracy of hot strip gage is strictly demanded, and the strip thickness becomes the most important quality in hot strip rolling. It is well known that the accuracy of final strip thickness in the hot strip mill depends on the gage control performance at each stand. In order to improve the quality of the hot strip gage and reduce the strip thickness deviation , the Automatic Gage Control(A.G.C) system now is widely used in modern hot strip mills of the world. In this paper, the principle of feedforward control strategy in the AGC system is discussed and it¡¦s control performance is deeply analyzed. Besides, based on the study of comprehensively mathematical model and the establishment of simulator, the mathematical analysis and the simulation result can clarify the influence of the control system on strip thickness.

Includes bibliographical references (p. 91-94).