In this thesis, we will firstly study the capacitive surface. By combining it with microstrip antenna, we can understand its effects on the properties of antenna, and investigate its miniature property. Next, we will design an electromagnetic band-gap (EBG) structure without vias to reduce the fabrication cost, and propose a best way of surrounding to combine EBG with antenna. In this way, we can improve the shortcomings of microstrip antenna, such as low gain and back radiation, etc. We will also apply our EBG to MIMO to reduce the mutual coupling and enhance gain. Then we make the MIMO antennas in a mobile device possible by shortening the distance between antennas. Finally, we can effectively shorten the distance and enhance performance even more by using miniature EBG. Both the fabrication and measurement will also be performed.

In this thesis, we discuss the subject into four parts. Firstly, we introduce the telematics for automotive. Secondary, we study the effects of locations of the hidden antenna. Thirdly, we discuss the effects of the windshield to the hidden antenna as we place the antenna on the windshield, then, the window film is attached to the windshield. We conduct implementation and measurement to analyze the effect of the film to the antenna. Finally, we find that the antenna gain is degraded in certain receiving angle due to the car body as we place the antenna at the corner of the windshield. In order to improve this, we design an EBG structure and place it between the antenna and the car body. The simulation result indicates that the EBG structure not only improves the gain in certain receiving angles but also reduces the induced current intensity on the car body.

No description available.

This dissertation is focused on design of compact electromagnetic magnetic band-gap structures (EBG). Several popular compact techniques are introduced and analyzed with equivalent surface impedance model. A novel compact EBG structure is investigated. Compared to the conventional uniplanar compact photonic band gap (UC-PBG) structure, a size reduction of 64.7% is achieved. A distinctive band gap is observed at 2.45 GHz with around 100 MHz bandwidth and zero reflection phase. Antenna applications of this novel EBG structure, including EBG patch antenna and EBG antenna array, have been presented. Simulation results further verify its characteristic of suppressing surface waves. For the EBG patch antenna, a more focused radiation pattern is obtained compared to a normal patch antenna. For an antenna array, the presence of EBG structure reduces the mutual coupling between the two radiating elements by 6 dB.

In conventional design of power delivery networks (PDNs), the PDN impedance is required to be less than the target impedance over the frequency range of interest to minimize the IR drop and to suppress the inductive noise during data transitions. As a result, most PDNs in high-speed systems consist of power and ground planes to provide a low-impedance path between the voltage regulator module (VRM) and the integrated circuit (IC) on the printed circuit board (PCB). For off-chip signaling, charging and discharging signal transmission lines induce return currents on the power and ground planes. The return current always follows the path of least impedance on the reference plane closest to the signal transmission line. The return current path plays a critical role in maintaining the signal integrity of the bits propagating on the signal transmission lines. The problem is that the disruption between the power and ground planes induces return path discontinuities (RPDs), which create displacement current sources between the power and ground planes. The current sources excite the plane cavity and cause voltage fluctuations. These fluctuations are proportional to the plane impedance since the current is drawn through the PDN by the driver. Therefore, low PDN impedance is required for power supply noise reduction. Alternatively, methods of preventing RPDs can be used to suppress power supply noise. Using a power transmission line (PTL) eliminates the discontinuity between the power and ground planes, thereby preventing the RPD effects. In this approach, transmission lines replace the power plane for conveying power from the VRM to each IC on the PCB. The PTL-based PDN enables both power and signal transmission lines to be referenced to the same ground plane so that a continuous current path can be formed, unlike the power-plane-based PDN. As a result, a closed current loop is achieved, and the voltage fluctuation caused by RPDs is removed in idealistic situations. Without the RPD-related voltage fluctuation, reducing the PDN impedance is not as critical as in the power-plane-based approach. Instead, the impedance of the PTL is determined by the impedance of the signaling circuits. To use the PTL-based PDN in a practical signaling environment, several issues need to be solved. First, the dc drop coming from the source termination of the PTL needs to be addressed. The driver being turned on and off dictates the current flow through the PTL, causing the dc drop to be dynamic, which depends on the data pattern. Second, impedance mismatch between the PTL and termination can occur due to manufacturing variations. Third, an increase in the number of PCB traces should be addressed by devising a method to feed more than one driver with one PTL. Lastly, the power required to transmit 1 bit of data should be optimized for the PTL by using a new signaling scheme and adjusting the impedance of the signaling circuit. Constant flow of current through the PDN is one solution proposed to address the first two issues. Constant current removes the dynamic characteristics of the dc drop by inducing a fixed amount of dc drop over the PTL. Moreover, constant current keeps the PTL fully charged at all times, and thereby eliminates the process of repeatedly charging and discharging the power transmission line. The constant current PTL (CCPTL) scheme maintains constant current flow regardless of the input data pattern. Early results on the CCPTL scheme have been discussed along with the measurements. The CCPTL scheme severs the link between the current flowing through the PTL and the output data of the I/O driver connected to it. Also, it eliminates the charging and discharging process of the PTL, thereby completely eliminating power supply noise in idealistic situations. To reduce any associated power penalty, a pseudo-balanced PTL (PBPTL) scheme is also proposed using the PTL concept. A pseudo-balanced (PB) signaling scheme, which uses an encoding technique to map N-bit data onto M-bit encoded data with fixed number of 1s and 0s, is applied. When the PB signaling scheme is combined with the PTL, the jitter performance improves significantly as compared to currently practiced design approach.

This dissertation is focused on design of compact electromagnetic magnetic band-gap structures (EBG). Several popular compact techniques are introduced and analyzed with equivalent surface impedance model. A novel compact EBG structure is investigated. Compared to the conventional uniplanar compact photonic band gap (UC-PBG) structure, a size reduction of 64.7% is achieved. A distinctive band gap is observed at 2.45 GHz with around 100 MHz bandwidth and zero reflection phase. Antenna applications of this novel EBG structure, including EBG patch antenna and EBG antenna array, have been presented. Simulation results further verify its characteristic of suppressing surface waves. For the EBG patch antenna, a more focused radiation pattern is obtained compared to a normal patch antenna. For an antenna array, the presence of EBG structure reduces the mutual coupling between the two radiating elements by 6 dB.

This thesis is devoted to potential applications of metamaterials in antenna structures as well as metamaterials behaviour, characterisation, structure design, simulation and extraction of parameters. The focus of this work is on the practical application of metamaterial structures for antenna performance enhancement. This thesis comprises three key parts; In the first part, theory of metamaterials is investigated including fields, polarisation, effective and average parameters, parameters extraction and transmission line (TL) model. In part two, zero index metamaterials (ZIM) theory is studied. The use of ZIM to form a highly directive medium is illustrated. A comparative study between different ZIM structures is conducted with a special attention to their operational bandwidth. ANSYS HFSS is used to model ZIM structures where simulation results show a bandwidth between 7.4% and 14.0%. Then two novel ZIM structures with a bandwidth of up to 33% are proposed. The first proposed ZIM is used to form a highly directive shell. Four directive shells are designed and placed around the dipole antenna where a gain increase of up to 6.8 dBi is obtained along the desired direction. Further, proposed ZIM cells are integrated with a quasi-Yagi antenna in order to increase its gain. Simulation results demonstrate gain enhancement for frequencies over which the proposed structure expresses ZIM properties. In part three, a new technique is stablished to design a metamaterial lens. The new technique is based on wave interference phenomena where engineered wave interference results in a desired spatial energy distribution. It is shown theoretically that having 180° phase difference between interfering waves results in a focused emission. Both hypothetical and metamaterial realisation models of a 180° phase shifter for a patch antenna are designed and simulated where a gain enhancement of 8 dBi and 5.77 dBi are achieved, respectively. Further, the concept of intended phase shift between interfering waves is used to design a novel bi-reflectional ground plane which can focus the reflected emission and consequently, increase the antenna directivity. In the theoretical model, the Perfect-E and Perfect-H planes are combined to form a bi-reflectional plane, whereas the practical model is designed using the copper cladding for the Perfect-E plane and the mushroom structure for the perfect-H plane. Both square and hexagonal geometries are used to form the mushroom structure. Simulation results confirm a gain enhancement of 5.4 dBi for the design using the square mushroom structure and a gain enhancement of 3.3 dBi for the design using the hexagonal mushroom structure.

In broadband antenna applications, the antenna's cavity is usually loaded with absorbers to eliminate the backward radiation, but in doing so the radiation efficiency of the antenna is decreased. To enhance the radiation efficiency of the antennas EBG structures are used, but they operate over a narrow band. Uniform electromagnetic band gap (EBG) structures are usually periodic structures consisting of metal patches that are separated by small gaps and vias that connect the patches to the ground plane. The electrical equivalent circuit consists of a resonant tank circuit, whose capacitance is represented by the gap between the patches and inductance represented by the via. EBG structures are equivalent to a magnetic surface at the frequency of resonance and thus have very high surface impedance; this makes the EBG structures useful when mounting an antenna close to conducting ground plane, provided the antenna's currents are parallel to the EBG structure. Because EBG structures are known to operate over a very narrow band, they are not useful when used with a broadband antenna. Mushroom-like uniform EBG structures (that use vias) are compact in size have low loss, can be integrated into an antenna to minimize coupling effects of ground planes and increase radiation efficiency of the antenna. The bandwidth of an EBG structure is defined as the band where the reflection-phase from the structure is between +900 to -900. In this dissertation analysis of EBG structures is established using circuit analysis and transmission line analysis. Methods of increasing the bandwidth of EBG structures are explored, by cascading uniform EBG structures of different sizes progressively and vertically (stacked), and applications with different types of antennas are presented. Analyses in this dissertation are compared with previously published results and with simulated results using 3D electromagnetic tools. Validation of applications with antennas is carried by manufacturing prototypes and comparing measured performance with analysis and 3D electromagnetic simulations. The improvements in performance by using wideband progressive EBG and wideband stacked EBG structures are noted. / Ph. D.

This thesis studies a new class of high gain planar resonant cavity antennas based on metamaterial surfaces. High-gain planar antennas are becoming increasing popular due to their significant advantages (e.g. low profile, small weight and low cost). Metamaterial surfaces have emerged over the last few years as artificial structures that provide properties and functionalities not readily available from existing materials. This project addresses novel applications of innovative metamaterial surfaces on the design of high-gain planar antennas. A ray analysis is initially employed in order to describe the beamfonning action of planar resonant cavity antennas. The phase equations of resonance predict the possibility of low-profile/subwavelength resonant cavity antennas and tilted beams. The reduction of the resonant cavity profile can be obtained by virtue of novel metamaterial ground planes. Furthermore, the EBG property of metamaterial ground planes would suppress the surface waves and obtain lower backlobes. By suppressing the TEM mode in a resonant cavity, a novel aperture-type EBG Partially Reflective Surface (PRS) is utilized to get low sidelobes in both planes (E-plane and H-plane) in a relatively finite structure. The periodicity optimization of PRS to obtain a higher maximum directivity is also investigated. Also it is shown that antennas with unique tilted beams are achieved without complex feeding mechanism. Rectangular patch antennas and dipole antennas are employed as excitations of resonant cavity antennas throughout the project. Three commercial electromagnetic simulation packages (Flomerics Microstripes ™ ver6.S, Ansoft HFSSTM ver9.2 and Designer ™ ver2.0) are utilized during the rigorous numerical computation. Related measurements are presented to validate the analysis and simulations.

The integration of mixed-signal systems has long been a problem in the semiconductor industry. CMOS System-on-Chip (SOC), the traditional means for integration, fails mixed-signal systems on two fronts; the lack of on-chip passives with high quality (Q) factors inhibits the design of completely integrated wireless circuits, and the noise coupling from digital to analog circuitry through the conductive silicon substrate degrades the performance of the analog circuits. Advancements in semiconductor packaging have resulted in a second option for integration, the System-On-Package (SOP) approach. Unlike SOC where the package exists just for the thermal and mechanical protection of the ICs, SOP provides for an increase in the functionality of the IC package by supporting multiple chips and embedded passives. However, integration at the package level also comes with its set of hurdles, with significant research required in areas like design of circuits using embedded passives and isolation of noise between analog and digital sub-systems. A novel multiband balun topology has been developed, providing concurrent operation at multiple frequency bands. The design of compact wideband baluns has been proposed as an extension of this theory. As proof-of-concept devices, both singleband and wideband baluns have been fabricated on Liquid Crystalline Polymer (LCP) based organic substrates. A novel passive-Q based optimization methodology has been developed for chip-package co-design of CMOS Low Noise Amplifiers (LNA). To implement these LNAs in a mixed-signal environment, a novel Electromagnetic Band Gap (EBG) based isolation scheme has also been employed. The key contributions of this work are thus the development of novel RF circuit topologies utilizing embedded passives, and an advancement in the understanding and suppression of signal coupling mechanisms in mixed-signal SOP-based systems. The former will result in compact and highly integrated solutions for RF front-ends, while the latter is expected to have a significant impact in the integration of these communication devices with high performance computing.