by Tan Wai Pin. / Thesis (M.Phil)--Chinese University of Hong Kong, 1993. / Includes bibliographical references. / DEDICATION --- p.ii / ABSTRACT --- p.iii / ACKNOWLEDGMENTS --- p.ix / Chapter CHAPTER 1 --- p.10 / Chapter 1 --- INTRODUCTIONS --- p.10 / Chapter 2. --- REFERENCE --- p.15 / Chapter CHAPTER 2 --- COMPUTATION OF CYLINDER FUNCTIONS --- p.17 / Chapter 1. --- INTRODUCTION --- p.17 / Chapter 2. --- NEED OF COMPUTING CYLINDER FUNCTION OF COMPLEX ARGUMENTS --- p.18 / Chapter 3. --- NEED OF COMPUTING HANKEL FUNCTIONS --- p.19 / Chapter 4. --- OUTLINE OF APPROACH --- p.22 / Chapter 5. --- ALGORITHMS --- p.24 / Chapter 5.1. --- REGION 1: IM(Z) < 5 AND RE(Z)<16 : --- p.25 / Chapter 5.1.1. --- Computation of Jn(z) : --- p.25 / Chapter 5.1.2. --- Determination of Starting Index M: --- p.26 / Chapter 5.1.3. --- Determination of Normalization Constant : --- p.26 / Chapter 5.1.4. --- "Computation of Yn(z),Hn(1)(z) and Hn(2) (z)" --- p.29 / Chapter 5.2. --- REGION 2 : --- p.30 / Chapter 5.3. --- REGION 3 : --- p.32 / Chapter 5.3.1 --- Computation of Jn(z) : --- p.52 / Chapter 5.3.2 --- "Computation of Hn(1) (z),H(n2)(z) and Yn(z) :" --- p.40 / Chapter 5.3.3 --- Determination of Point of Starting Exponential Scaling : --- p.42 / Chapter 5.4. --- REGION 4 : --- p.42 / Chapter 5.5. --- REGION 5 : --- p.42 / Chapter 6. --- VERIFICATION --- p.43 / Chapter 7. --- REFERENCE --- p.46 / Chapter CHAPTER 3 --- INPUT IMPEDANCE OF CYLINDRICAL-RECTANGULAR MICROSTRIP ANTENNA --- p.48 / Chapter 1. --- INTRODUCTION --- p.48 / Chapter 2. --- FORMULATION --- p.49 / Chapter 3. --- DISCUSSION --- p.62 / Chapter 4. --- REFERENCES --- p.68 / Chapter CHAPTER 4 --- MUTUAL IMPEDANCE OF CYLINDRICAL-RECTANGULAR MICROSTRIP PATCH ANTENNAS --- p.70 / Chapter 1. --- INTRODUCTION --- p.70 / Chapter 2. --- FORMULATION --- p.70 / Chapter 3. --- DISCUSSION --- p.77 / Chapter 4. --- REFERENCES --- p.83 / Chapter CHAPTER 5 --- RESONANCE OF RECTANGULAR MICROSTRIP ANTENNA INSIDE A METALLIC CYLINDER --- p.84 / Chapter 1. --- INTRODUCTION --- p.84 / Chapter 2. --- FORMULATION --- p.85 / Chapter 3. --- NUMERICAL RESULTS --- p.96 / Chapter 4. --- CONCLUSION --- p.98 / Chapter 5. --- REFERENCES --- p.102 / Chapter CHAPTER 6 --- INPUT IMPEDANCE OF RECTANGULAR MICROSTRIP ANTENNA INSIDE A METALLIC CYLINDER --- p.104 / Chapter 1. --- INTRODUCTION --- p.104 / Chapter 2. --- FORMULATION --- p.104 / Chapter 3. --- NUMERICAL RESULTS --- p.106 / Chapter 4. --- CONCLUSION --- p.111 / Chapter 5. --- REFERENCES --- p.112 / Chapter CHAPTER 7 --- SUMMARY --- p.113 / APPENDIX A --- p.117 / APPENDIX B --- p.119 / PUBLICATION LIST : --- p.121

A delay line phase shifter for the 30-70 GHz range is presented that uses an aluminum micro-ribbon array fabricated in the ground plane of a microstrip transmission line. Phase shift is achieved by changing the propagation velocity of an RF signal in the transmission line by controlling the effective permittivity of the substrate. This is done by actuating the micro-ribbons away from the substrate. This phase shifter has the benefits of analog phase shifts and high Figure of Merit. Simulations were done to model the micro-ribbon deflections, transmission line performance and phase shift. Arrays of 5, 10, and 20 μm wide micro-ribbons were fabricated and tested. At 40.80 GHz, the 20 μm wide micro-ribbons had a measured phase shift of 33º with an actuation voltage of 120 V. The corresponding Figure of Merit was a negative value indicating that there was no line loss due to ribbon deflection. / February 2008

In recent years, microstrip antennas are suitable for applications in wireless communication systems because they have the characteristics of compact size, light weight, low cost and easy to manufacture. So, they play an important role in the navigation equipment of the rocket, space shutter, personal communication, etc. However, in the design and synthesis of antennas, there are a large number of design variables that affect the antenna performance. In early stages, some researchers did not use any optimization tool in parameter tuning of antennas design. The one utilized most is the ¡§trial and error¡¨ method, which is very time-consuming in order to find a suitable solution to verify the possibilities of the antenna structure. Genetic algorithms have been shown to be effective in the design of broadband microstrip antenna. However, their effectiveness with various degrees depends on the skills of the different genetic algorithms. In this dissertation, we propose a Genetic Algorithm (GA)-based refined method to enhance the effectiveness and to solve the gap-coupled microstrip antenna design problem (largest impedance bandwidth). The refined method with optimization process improves the computing performance comparing with the conventional genetic algorithm. By the refined GA method, bandwidth can be widened up to 3.84 times that of a single excited patch. Furthermore, we present a new design for Ultra Wideband (UWB) antenna. In the new research topic, it is expected that the genetic algorithm can find out a range of feasible (range-based) solutions instead of a few of solutions. As a result, the manufacturing process will have more convenience and practicability. Finally, we propose a new method to overcome the problem of signal interference with the UWB system operations. A band notched characteristic is achieved for the antenna to restrain the interference bandwidth. The disclosed antenna and the circuitry for the antenna system are easily integrated. With the simple structure, the fabrication cost for the antenna is also reduced.

Novel broadband designs of microstrip antennas have been proposed in this dissertation, including bandwidth enhancement using integrated reactive loading, broadband circularly polarized designs, broadband dual-frequency design, bandwidth enhancement using a slotted ground plane and practical applications. First, bandwidth enhancement of microstrip antennas using integrated reactive loading is proposed and experimentally studied. Results show that the proposed antennas can have an operating bandwidth more than 2.0 times that of a conventional one at a given operating frequency. Second, by selecting a thick air substrate, a wideband circularly polarized microstrip antenna with improved CP quality has been implemented. In addition to the improved CP quality obtained, a 2-dB axial-ratio bandwidth as large as about 38% is also achieved. Third, by bending a planar rectangular patch into an inverted L-shaped patch, a dual-frequency planar antenna has been obtained. Experimental results show that the proposed antenna has a tunable frequency ratio of about 1.66-2.29. Fourth, by embedding meandering slots or slits in the antenna¡¦s ground plane, it is observed that the impedance bandwidth of the microstrip antenna is twice larger than the conventional one. The experimental results show that the resonant frequency is significantly lower, which can lead to a large antenna size reduction for a fixed frequency operation. In addition, enhanced antenna gain is also obtained. Finally, a shorted patch antenna suitable for applications in DCS (1710-1880 MHz) base station is presented.

A delay line phase shifter for the 30-70 GHz range is presented that uses an aluminum micro-ribbon array fabricated in the ground plane of a microstrip transmission line. Phase shift is achieved by changing the propagation velocity of an RF signal in the transmission line by controlling the effective permittivity of the substrate. This is done by actuating the micro-ribbons away from the substrate. This phase shifter has the benefits of analog phase shifts and high Figure of Merit. Simulations were done to model the micro-ribbon deflections, transmission line performance and phase shift. Arrays of 5, 10, and 20 μm wide micro-ribbons were fabricated and tested. At 40.80 GHz, the 20 μm wide micro-ribbons had a measured phase shift of 33º with an actuation voltage of 120 V. The corresponding Figure of Merit was a negative value indicating that there was no line loss due to ribbon deflection.

A delay line phase shifter for the 30-70 GHz range is presented that uses an aluminum micro-ribbon array fabricated in the ground plane of a microstrip transmission line. Phase shift is achieved by changing the propagation velocity of an RF signal in the transmission line by controlling the effective permittivity of the substrate. This is done by actuating the micro-ribbons away from the substrate. This phase shifter has the benefits of analog phase shifts and high Figure of Merit. Simulations were done to model the micro-ribbon deflections, transmission line performance and phase shift. Arrays of 5, 10, and 20 μm wide micro-ribbons were fabricated and tested. At 40.80 GHz, the 20 μm wide micro-ribbons had a measured phase shift of 33º with an actuation voltage of 120 V. The corresponding Figure of Merit was a negative value indicating that there was no line loss due to ribbon deflection.

Les dispositifs électroniques modernes comportent souvent une ou plusieurs phases de veille, dans lesquelles elles attendent un ordre de réveil de la part d’un actionneur distant (une télécommande). Ces types de dispositifs ont tendance à être de plus en plus présents dans les habitations et dans les bâtiments tertiaires, en particulier dans le domaine de la domotique. Les phases de veille sont caractérisées par des niveaux de consommations très inférieures aux consommations en mode actif des dispositifs, mais les durées de veille sont généralement grandes devant les périodes actives. Ce fait, combiné à la multiplication des dispositifs, mène à des consommations annuelles qui peuvent dépasser 10 % de la facture d’électricité des ménages. Cette étude propose une nouvelle approche de réveil des dispositifs en veille. Au lieu d’avoir une écoute permanente en réception et d’envoyer une trame d’informations de réveil, le récepteur est complètement endormi et est réveillé à travers une impulsion d’énergie transmis par d’ondes électromagnétiques. Une fois que l’étage d’interprétation des données est alimenté, un envoi d’informations est effectué pour valider l’ordre de réveil. En vue des portées attendues pour le système et des contraintes normatives liées aux expositions des personnes aux champs électromagnétiques, une faible quantité d’énergie est disponible en réception pour le réveil du dispositif. Plusieurs topologies de circuits de rectification RF-DC (rectenna) en technologies microstrip sont étudiées à travers des simulations circuit et électromagnétiques. La topologie choisie a été optimisée pour fournir un bon niveau de tension DC pour des faibles niveaux de puissance RF incidente. Une adaptation entre le convertisseur et l’antenne de réception différente de 50 W a été utilisée. Tous ces résultats ont été validés expérimentalement. Au niveau du circuit de réception des données, plusieurs scénarios de fonctionnement ont été comparés. L’étage de démodulation utilise la rectenna comme détecteur à diodes, pour réduire au maximum la consommation et la complexité de mise en œuvre. Le système global a été testé et des gains substantiels sont constatés sur le bilan de consommation annuelle de plusieurs types des dispositifs, comparé à un fonctionnement classique. En parallèle, une architecture de récepteur d’énergie électromagnétique reconfigurable est proposée. Il offre l’avantage de pouvoir exploiter une large gamme de puissance incidente, ce qui n’est pas le cas des structures de rectennas classiques. Des rectennas en technologies discrètes et intégrées sont utilisées, connectées à une antenne commune à travers un switch d’antenne intégrée. Le système proposé est adaptatif et les résultats des tests montrent des améliorations notables de la quantité d’énergie collectée par rapport à des rectennas individuelles. Enfin, le phénomène de l’inversion de la tension dans une association déséquilibrée de rectennas est mis en évidence et des solutions sont proposées. / Modern electronic devices often include one or more phases of stand-by, where they waiting for a wakeup order from a distant actuator (remote control). These devices tend to be increasingly present in homes and in commercial buildings, especially in the field of building automation systems. Stand-by periods are characterized by consumption levels well below those in active mode, but stand-by periods are generally large compared to active periods. This fact, combined with the proliferation of devices, leads to annual consumption which may exceed 10% of the annual household electricity bill. This study proposes a new approach to waking up of stand-by devices. Instead of continuous monitoring of the arrival of the wake-up signal, the receiver is completely asleep and woke up through a pulse of energy transmitted via electromagnetic waves. Once the data receiver module is activated, information is sent to validate the wake-up order. In view of the expected ranges for the system and normative constraints related to exposures to electromagnetic fields, only a small amount of energy is available at receiver level for performing the wake-up. Several RF-DC rectification circuit (rectenna) topologies in microstrip technology are studied through circuit and electromagnetic simulation. The chosen topology has been optimized to provide a good level of DC voltage at low levels of incident RF power. A matching impedance other than 50 W between the converter and the receiving antenna was used. All these results have been validated experimentally. For the data receiver circuit, several operating scenarios were compared. The demodulation stage uses the rectenna as a diode detector to minimize consumption and complexity of implementation. The overall system has been tested and substantial gains are obtained for several types of devices, in terms of annual consumption, compared to classical stand-by devices. At the same time, a reconfigurable electromagnetic energy receiver architecture is proposed. It offers the advantage of exploiting a wide range of incident power, which is not the case of conventional rectenna structures. Rectennas fabricated in discrete and integrated technology are used, connected to a common antenna through an integrated antenna switch. The proposed system is self-adaptive and the test results show significant improvements in the amount of energy collected compared to individual rectennas. Finally, the phenomenon of voltage reversal in unbalanced rectenna associations is highlighted and possible solutions are proposed.

No / It is shown that a conical beam 5.2-GHz antenna suitable for HIPERLAN application, but working in horizontal polarization, can be realized as a group of microstrip patch radiators in a ring formation. Layouts with three and four patches are described, and radiation patterns are found to agree well with predictions from a simple array model. The three-patch form is smaller and gives a closer approximation to an azimuth-independent pattern. Patterns are very similar to those achieved in vertical polarization with previously reported disk antenna realizations, giving peak radiation at about 50 elevation. Two methods of impedance matching are found to give satisfactory results. A dual-polarized conical-beam microstrip antenna, with a strictly uniplanar conductor pattern, is also presented and realized as an array of three square patches whose corners meet a central feed point. For the second polarization, the antenna functions as a series fed array. Fairly good conical beam patterns have been obtained, though only moderate polarization purity appears to be obtainable from threeelement arrays.

The aim of this thesis is to identify coupling mechanisms for three line microstrip, stripline and microstrip with dielectric overlay structures as either inductive or capacitive, quantify through simulation and measurement the amount of crosstalk to be expected in terms of scattering parameters. A new method of crosstalk suppression is implemented into each three line structure by placing uniformly spaced short circuits down the length of the center transmission line. All structures were simulated over various physical and electrical parameters. Select microstrip structures, shielded and unshielded, were fabricated and measured to validate the effectiveness of the shielding technique. Shielding effectiveness was calculated from the measurements, and their results showed that the isolation between lines was increased by up to 20dB.

The designs of various feeding networks for microstrip antennas have been investigated in this dissertation. In the active microstrip antenna designs, an amplifier-type microstrip antenna integrates a two- port amplifier circuitry to the various passive antennas through a 50£[ inset microstrip feed line which can function in broadband operation¡ACP operation and dual-frequency operation. As for the broadband circularly polarized microstrip antenna with a dual-perpendicular feed design, antenna with a dual-perpendicular feed which was formed by a Wilkinson power divider with a quarter-wavelength section of microstrip line for providing equal splitting of the input power and 90¢X phase difference to the two feed points has been presented. The broadband CP bandwidth can be achieved due to the good isolation between the two output lines of the feed network. In the microstrip antennas with CPW feed designs, we first proposed a microstrip antenna with three-dimensional CPW feed. A separate feed substrate is used which can provide a large-area space for the layout of complicated microwave circuitry. In addition, the feed substrate can also be oriented to the patch substrate with various angles, resulting in more flexibility in the proposed three-dimensional feed design. Finally, we proposed a design with two slot lines located at both sides of the coupling slot which can lengthen the excited patch surface current path, thus the resonant frequency is reduced and an antenna size reduction up to 40% has been obtained.