In this dissertation, many novel low-cost planar antenna designs are presented for on-vehicle applications. Promising planar antennas showing the desired broadside and omnidirectional radiation patterns and having low-profile configurations are demonstrated. Also, studies on controlling the radiation patterns are conducted. Details of the measured and simulated results of the studied antennas are presented and discussed.

Design considerations and experimental results of a dual-band circularly polarized stacked microstrip antenna for GPS operations at 1227 and 1575 MHz are presented. The antenna is achieved by stacking two corner-truncated square microstrip patches. The obtained circular polarization (CP) bandwidths, determined from 3-dB axial ratio, are about 15 MHz (about 1.2%) and 17 MHz (about 1.1%) at 1227 and 1575 MHz, respectively. Good CP radiation patterns and antenna gain have also been observed.

Yes / Two miniature low profile PIFLA antennas with a compact volume size of 30mm × 15mm × 8mm has presented in this paper. By applying the magnetic wall concept a reduced size dual-band and a wideband half PIFLAs for WLAN (2.4GHz/5.2GHz) and UWB applications are achieved. The dual-band antenna shows a relative bandwidth of 12% and 10.2% at ISM2400 and IEEE802.11a frequency bands respectively for input return loss less than 10dB. By carefully tuning the geometry parameters of the dual-band proposed antenna, the two resonant frequencies can be merged to form a wide bandwidth characteristic, to cover 3000MHz to 5400 MHz bandwidth (57%) for a similar input return loss that is fully covering the lower band UWB (3.1-4.8GHz) spectrum. The experimental and simulated return losses on a small finite ground plane of size 30mm × 15mm show good agreement. The computed and measured radiation patterns are shown to fully characterize the performance of the proposed two antennas. / MSCRC

The introduction of the so-called metamaterials, artificial materials which have engineered electromagnetic responses that are not readily available in nature, and their exotic properties have provided an alternate design approach that has led to improved performance characteristics of several radiating and scattering systems. This dissertation work introduces an antenna design paradigm based on the incorporation of metamaterials, which have negative permittivity and/or permeability medium properties, with simple radiating elements to obtain efficient electrically-small antenna systems. The most general analytical form of the electrically-small electric dipole antenna in the presence of a multilayered metamaterial shell system is developed and the total radiated power of this system is optimized using a hybrid genetic algorithm(GA)-MATLAB optimization approach. The numerical modeling of more realistic antenna-metamaterial systems confirms the analytical results. The theoretical and numerical studies of their radiation and resonance behaviors have led this dissertation work to the discovery of the first physical two- (2D) and three-dimensional (3D) metamaterial based and inspired efficient electrically-small antenna systems. Several novel metamaterial-inspired electrically-small antenna systems, i.e., the 2D and 3D electrical- and magnetic-based EZ antennas, are reported and are shown to be naturally matched to a 50 Ohms source and, hence, to have high overall efficiencies. The proposed 2D and 3D EZ antenna systems are linearly scalable to a wide range of frequencies. Several versions of the 2D EZ antennas were fabricated and tested. The measurement results confirm the performance predictions. This dissertation also considers several new metamaterial structures. An artificial magnetic conductor (AMC) slab is designed to achieve its in-phase reflection properties in the X-band at 10 GHz without the presence of a PEC ground plane. A block of this AMC structure was designed, fabricated, tested, and then integrated with a dipole antenna to realize a resonant low profile antenna system having a large front-to-back ratio.

There is a demand for compact, low profile, and wideband antennas for modem wireless devices. The purpose of this dissertation is to develop two such antennas. A method of moments and finite difference time domain method are used for the design and analysis of the antennas. A new microstrip antenna is designed which has more than 90 % bandwidth. The operation of the antenna is explained and design equations are developed. The antenna is integrated with electromagnetic band gap structures (EBG) to examine if performance enhancement is possible. The simulation results are verified by limited measurements. A wideband loop antenna is also integrated with EBGs and significant perfbrrnance improvement is achieved.

A dissertation submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg, infulfilment of the requirements for the degree of Master of Science in Engineering Johannesburg, 1989 / T his dissertation examines simple Meteor Burst Communication (M B C) out-starioL * i-^nas. The eSect o f illum ination gain, beam w idth and orientation was studied using computer ^vr.t-iation. Sim ilarly, the performance o f M B C links using a half-wave dipole, a quarter-wave rnonopole, a square loop, a long w ue and a 5-elements Yagi-Uda antennas was determined. The performance o f these links are related to the antennas’ sky i l l umination. This investigation provides designers some bench-mark results which indicate the role played by the antennas ’ radiation patterns in M B C. A value system was formulated to provide practical and electrical trade-offs fo r m obile andmanpack antennas in the meteor scatter environment. Simulated results indicate that simple antennas cause degraded communications due to their reduced size and complexity. The conclusion is that the directional master station should provide adequate sky illumination. I t is recommended that the results obtained be validated by measurements and further work concentrate on master station antennas.

by Au Tsien Ming. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1992. / Includes bibliographical references (leaves 100-101). / Acknowledgments / Chapter Chapter 1 --- Introduction --- p.1 / Chapter Chapter 2 --- Analysis of Linearly Polarized Stacked Rectangular Microstrip Antenna / Chapter 2.1 --- Green's Function Formulation --- p.4 / Chapter 2.1.1 --- Field Components --- p.5 / Chapter 2.1.2 --- Boundary Conditions --- p.7 / Chapter 2.2 --- Galerkin's Method --- p.22 / Chapter 2.3 --- Numerical Computation --- p.27 / Chapter 2.4 --- Illustrative Results --- p.40 / Chapter Chapter 3 --- Analysis of Circularly Polarized Stacked Rectangular Microstrip Antenna / Chapter 3.1 --- The Range of Applications --- p.70 / Chapter 3.2 --- Analyzed Results and Discussion --- p.71 / Chapter Chapter 4 --- Conclusion --- p.98 / Reference --- p.100 / Appendix / Chapter A1 --- List of Symbols --- p.102 / Chapter A2 --- Publication List of the studies --- p.106

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 119-124).

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